LAB MANUAL - Best Engineering College in Sangrur, Punjab
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1. The dynamic brake tester has rollers in the floor The two wheels whose brakes are to be tested are placed on the rollers If these are the drive wheels the wheels are spun at the specified speed by the vehicle engine or otherwise the wheels are spun by an electric motor Then the throttle is released or the electric motor is turned off and the brakes are applied The braking force at each wheel registers on meters This shows if the brakes perform normally or if they need service 2 NX A ROLLER NS A NZ VY Platf t brake test Ye DEM VESISE Dvnamic Brake Tester Replacing drum brake shoes When linings wear the brake shoes must be replaced To replace the shoe in a drum brake the wheel amp brake drum must be removed Then shoes with new linings are installed Although been a practice years ago brake shoes are relined at few locations even todav ntil a few years ago most relined shoes were arced This meant the shoes were ground slightly to better fit the larger diameter of a used or refinished brake drum However grinding brake shoe is no longer universally recommended This is because of the hazards resulting from the asbestos dust created during shoe grinding ADJUSTER SCREW vA RETURN SPRING AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Servicing brake amp drums Brake disk requires replacement only if they become deeply scored or are wrapped out of line Light scores o2. gapping them Always select and install the correct spark plugs for the engine First inspect and gap the plugs to the manufacturer s specification CONTACT POINT SERVICE Burned or worn contact points should be replaced They are supplied in sets one stationary point one movable point on the contact arm Some sets are supplied assembled with an attached AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL condenser Adjustment is made by turning an eccentric or by moving the stationary contact point support AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 4 Objective Demonstration of steering system by measurement of steering Geometry angles amp their impact on vehicle performance Theory The steering system allows the driver to guide the car along the road amp turn left or right as desired The system included the steering wheel which the driver controls the steering gear which the driver change the rotary motion of the wheel into straight line motion amp the steering linkages Most systems were manual until a few years ago Then power steering became popular It is now installed on about 90 percent of cars manufactured in the United State today Demonstration of steering system Types of Steering System i Pitman arm steering gears Steering linkage using pitman arms are shown The steering or at the lower end of the steering shaft consists essentiall
3. If the driver has the habit of riding the clutch by resting the left foot on the pedal part of the pressure plate spring force will be taken up so that slippage may take place Likewise frequently use of the clutch incorrect clutching amp declutching overloading the clutch amp slow clutch engagement amp disengagements increase dutch facing wear Part B Function of differential A differential is required to compensate for the difference in distance that the drive wheels travel when the car rounds a curve If a right angle turn were made with the inner rear wheel turning on a 20 foot 6 1 m radius the inner rear wheel would travel about 31 feet 9 5m while the outer rear wheel would travel about 39 fe t 12m The differential permits power flow to both drive wheels while allowing the wheels to turn different distance when the car is rounding a curve DRTV6 SHAFT TO WHEEL Operation of differential When the car is on a straight road the ring gear differential case differential pinion gears and two differential side gears all turn as a unit The two differential pinion gears do not rotate on the pinion shaft This is because they exert equal force on the two differential side gears As a result the side gears turn at the same speed as the ring gear which causes both drive wheels to turn at the same speed also Differential trouble diagnosis Humming A humming noise is often caused by incorrect internal adjustment o
4. They may break piston rings installed upside down may cause excessive oil consumption AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL The piston rings must be fitted to the ring grooves in the piston and also to cylinder If you are fitting rings to a tapered cylinder check the ring end gap at the lower limit of ring travel PISTON Theory Pistons are usually made of aluminum alloy which is a mixture of aluminum and other metals Automotive pistons weigh about 1 pound 0 454 kg they are a sliding fit in the cylinders This means the pistons can slide up and down in the cylinders This means the pistons are slightly smaller in diameter than the cylinders Diagram TNT PUT ke CONNECTING ROD Piston Service After the piston and rod assemblies are removed from the engine the pistons and rods should be separated Then the rings can be removed from the pistons The rings can also be removed from the pistons before the pistons and rods are separated A piston ring expander can be used for ring removal The tool has two small tangs that catch under the ends of ring When force is applied to the tool handles the ring is opened slightly so it can be lifted out of the ring groove and off the piston Install new rings during an engine overhaul Once the ring break in coating and tool marks are worn off the ring will not reset itself if it is reinstalled Piston Cleaning Remove carbon and varnish caref
5. amp TECHNOLOGY DEPPT OF MECHANICAL Complaint Possible causes Check or correction All brake drags Incorrect linkage adjustment Adjust Trouble in master cylinder Repair or replace Mineral oil in system Replace damaged parts Car pulls to one side If the car pulls to one side when the brakes are applied more braking force is being applied on one side than to the other In a front engine rear wheel drive car linings will become soaked with oil if the lubrication level in the rear axle is too high this may cause leakage past the oil seal At the front wheels brake linings may get grease on them If the front wheel bearings are over lubricated or if the grease seal is defective or improperly installed Wheel cylinder will leak brake fluid onto the brake linings if the cups are defective if the cylinder bore is pitted or if an activating pin has been improperly installed If the linings at the left wheel become soaked with brake fluid or oil the car pulls to the left because the brakes are more effective on the car s left side However the direction of pull may depend on the type of friction material amp the contaminant Complaint Check or correction Car pull to one side Brake line clogged Clear or replace line Defective wheel cylinder Repair or replace Brake backing plate loose Tighten Mismatched linings Use same linings all around Soft or Spongy pedal If the pedal action is soft or spongy there is p
6. at normal engine temperatures AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL If ring gap correct insert the outside surface of the ring into the proper ring groove in the piston see in fig Then roll ring around in the groove to make sure the ring has a free fit around the entire piston An excessively tight fit probably means that the ring groove is dirty Another possibility is that the ring groove has been nicked or burred with the blade of ring groove cleaner Some companies recommend using the end of a broken ring which has been filed to a sharp edge to clean the ring grooves Some technicians prefer this because the piece of the ring will not cause nicks or burrs ro gt A Install the rings in the ring grooves using a piston ring expander Then measure the piston ring side clearance The clearance should be least 0 001 inch 0 025 mm and not more then 0 004 inch 0 10 mm for most engines Cautions on installing Piston Rings The three part oil rings are installed one part at a time various types of compression rings and their proper installed positions are shown in fig Never spiral the compression rings into the grooves Spiraling the rails of an oil ring is shown in fig This could bend or break the compression ring and cause loss of compression and blow by Instead always install compression rings with a piston ring expander Never over expand compression rings while installing them
7. clutch for service The recommendation of most manufacturers is it replaces the disk amp pressure plate assembly if there is internal wear or damage or weak springs Pressure plate assemblies can be rebuilt but this usually is a job for clutch rebuilder AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL 2 Clutch chatters or Grabs when Engaged Check the clutch linkage for binding It is binds could release suddenly to throw the clutch into quick engagement with a resulting heavy jerk A broken engine mount can also cause chattering because the engine is free to move excessively Inside the clutch the trouble could be due to oil or grease on the disk facings or to glazed or loose facings Clutch chatters or grabs Oil or grease on disk Replace facings or disks when engaged facings or glazed or loose facings Binding of friction disk hub Clean and lubricate on clutch shaft Splines replace defective parts Binding in clutch release Free adjust and Linkage lubricate 3 Clutch spins or drags when disengaged The first check is pedal linkages adjustment if there is excessive pedal lash or free travel even full movement of the pedal will not release the clutch faulty One cause of loose friction disk facings is abuse of the clutch This abuse includes popping the clutch for a quick gateway letting the clutch out suddenly with the engine turning at high rpm slipping the clutch for drag strip starts amp mod
8. graduated sizes to fit various sizes of cylinders Most packages include instructions that describe how to install the rings Follow these instructions carefully mUa Pressure J k As a first step the rings should be pushed down into the cylinder with a piston and the ring gap measured The ring gap is the space between the ends of the rings It is measured with a thickness gauge Figure shows the gap being measured with ring pushed down to the lower limit of ring travel If the cylinder is worn that is where the ring gap will be smallest If you may have the wrong ring set for the engine you may have incorrectly measured cylinder diameter or the wrong rings may have been packaged in the box Typical piston ring end gap in an automotive engine is from 0 010 to 0 020 inch 0 25 to 0 51 mm If the cylinder is tapered the diameter at the lower limit of the ring travel in the cylinder will be smaller then the diameter at the top Therefore the ring must be fitted to the diameter at the lower limit of ring travel If it is fitted to the upper part of the cylinder the ring gap will not be great enough at the lower limit of the ring travel As a result the ring ends will touch together The ring will be broken and the cylinder wall will be scored Always measure the ring gap with ring pushed down to its minimum diameter at the lower limit of ring travel The clearance should be wide enough so that the ring ends do not butt together
9. irregularly worn The valve seats are of two types the integral type and the insert type Replacing seat inserts and grinding seats are described below AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL 1 Replacing valve seat inserts A valve seat insert may be badly worn Or it may have been refinished previously so that there is insufficient metal With either condition the seat must be replaced the old seat must be removed with a special puller If the puller is not available the insert is punch marked on two opposite sides An electric drill is then used to drill holes almost through the insert Then a chisel and hammer can be used to break the insert into two halves so it can be removed Care must be taken so that the counter bore isn t damaged If the new insert fits too loosely the counter bore must be re bored over size Then an over size insert installed It may be necessary to chill the seat and heat the head before the seat is driven into place After installation the valve seat should be ground 2 Grinding valve seats The valve seat grinder rotates a grinding stone of proper shape on the valve seat A pilot installed in the valve guide keeps the stone concentric with the valve seat This means that the valve guide must be cleaned and serviced before the seat is ground In the seat grinder the stone is automatically lifted about once a revolution This permits the stone to clear it self o
10. of each other When the drum diameters on the same axle vary more than this replace both drums Wheel cylinder service Most wheel cylinders can be disassembled amp rebuilt on the car However many manufacturers recommend that the wheel cylinder be removed from the backing plate amp serviced on the bench This makes it easier to properly amp thoroughly clean inspect amp reassemble the cylinder To remove a wheel cylinder from the car first remove the wheel amp brake drum Then disconnect the brake hose or tube from the wheel cylinder Remove the wheel cylinder by taking out the attachment bolts or retainer Then tape the end of the hose or pipe shut to prevent any dirt from getting in Disassemble the wheel cylinder by first pulling off the boots Then push out the piston cups amp springs Clean all wheel cylinder pats in clean brake fluid Dry the parts with compressed air Then place the dried parts on clean lint free shop towels or paper Check that all passages in the wheel cylinder amp bleeder screws are clear by blowing through them with compressed air Inspect the cylinder bore for scoring amp corrosion Use crocus cloth to remove light corrosion amp strains Replace the wheel cylinder if crocus cloth does not remove the corrosion or if the bore is pitted or scored Some manufacturers permit the use of brake cylinder hone to remove scores amp rust However the cylinder bore must not be honed more than 0 003 0 08mm larger
11. pistons will be found with excessively worn top ring grooves The ring groove may be checked with a wear gauge If the ring groove is worn 0 006 inch 0 15 mm or more it can be machined to a larger width with a special hand operated lathe This squares up the top and bottom sides of the ring groove Then the new piston ring is installed with a spacer AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL _ E TOP GROOVE SPACER f Z u 15 PISTON E RING l a Piston Resizing automotive manufacturers do not recommend Resizing of collapsed or worn pistons Excessive resizing can weaken the piston One piston reconditioning procedure for older piston is knurling The piston skirt is run between a supporting wheels and a knurling tool This displaces metal which expands the diameter of the piston skirt The indentations from little pockets that can hold lubricating oil to reduce scuffing Selecting New Pistons New pistons are ready for assembly and installation when they are removed from the box They are available in various sizes for each engine usually known as Standard Oversize When oversize pistons are used the cylinders are rebored and then finished to fit the pistons Engine manufacturers supply oversize piston of the same weight as the original pistons This eliminates any balance problem with the engine when different size pistons are installed Some engine repairs may
12. rotor that allows high voltage leakage from one terminal to another or by high voltage cables being incorrectly connected Possible Causes Check or correction Moisture in Moisture in distributor cap cap Drycap cap across carbon paths Engine backfires but fails to High voltage cables not Reconnect cables correctly start connected in firing order Engine runs but misses An engine that runs misses runs unevenly and does not develop full power It is some time difficult to tell by listening whether one cylinder is missing or whether the miss is intermittent and jumping around from one cylinder to another if one cylinder is missing the cause could be a defective spark plug or high voltage cable a bad connection and high voltage leakage across the distributor cap or through the cable insulation In the engine the miss could be due to struck or burned valves or loss of compression resulting from broken piston rings Possible Causes Check or correction Engine runs but misses Spark plug s faulty Clean and regap or replace High voltage cables defective Defective coil or distributor cap 9 or rotor TRU AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Advance mechanism defective Check advances repair or replace distributor Engine runs but backfires Backfiring is a pop or bang in the exhaust manifold It can be caused by several conditions in the ignition system If the ignition timing i
13. steering effort Vertical Caster angle Centre line of steering ax Vertical Ball Joint EC EX Front of the Car Caster of the left front wheel as viewed from the driver s seat The view is from the inside so that the backward tilt of the steering axis from the vertical can be seen This backward tilt is called positive caster IDLER ARM AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL V PUN AD NG STEE SLEEVES X ARM nS NS SMA e TOE It is the amount in inches millimeters or degrees in which the front wheels point inward or outward Its purpose is to stabilize steering amp to prevent side slipping amp successive wear of the tyres Toe in The wheels are viewed from above with he front of the car at the lop of the illustration distance A is less than distance P f TURNING RADIUS It is sometimes called toe out during turns and turning angle It is the difference between the two angles formed by the two front wheels and the car during turn AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL TURNING RADIUS INNER WHEEL TOURA AG ANGLE CENTER Turning radius or toe out on turns g STEERING RATIO Out of the jobs of steering gear is to provide mechanical advantages In a machine or mechanical device this is the force supplied to it The steering ratio is the number of degrees that the steering wheels must be t
14. system is opened and closed by contact points In the electronic system the primary circuit is opened and closed by the electronic control unit ECU The secondary circuits are practically the same for the two systems The difference is that the distributor ignition coil and the wiring are altered to handle the higher voltage that the electronic ignition system produces One advantage of this higher voltage upto 47 000 volts is that spark plugs with wider gaps can be used This results in a longer spark which can ignite leaner air fuel mixtures As a result engines can run on leaner air fuel mixtures for better fuel economy and lower emissions Another difference is that some electronic ignition systems have no mechanical advantage mechanisms centrifugal or vacuum Instead the spark timing is adjusted electronically High Tension Lead ETENN Has Contact Dist ee LEE pum P Breaker ane oo ka jnition ne E st N A x le oy lt Switch r V E Wee s J j ele N Prunary S HOT Y e Winding ei SA l B S22 1 a au tS Id l N J 1 s escaso SS Nig r HE Gods i ES gt e p ignition 7 j I Coil Condenser I Secondary i j pee Winding i AL C y i i ps Battery ES x I eee s DIAGRAM Trouble shooting in ignition system Ignition system quick check Several checks have been used in the past to help locate the cause of various tr
15. than its original diameter If the scores do not clean out replace the cylinder The wheel cylinder also should be replaced if the clearance between the cylinders bore amp the piston is excessive When reassembling the wheel cylinder lubricate all parts with clean brake oil Then assemble the wheel cylinder using all parts in the repair kit Install the bleeder screw amp torque it to specifications Master cylinder service Master cylinder may require disassembly for replacement of internal parts However some technicians prefer to install a new or rebuilt cylinder The service procedures for master cylinder used with disk brakes amp drum brakes are very similar One difference is that with disk brakes a larger brake fluid reservoir is required With a braking system that has front wheel disk brakes amp rear wheel drum brakes Note that the fluid reservoir for the front disk brakes is larger than the other To service the master cylinder clean the outside Then remove the master cylinder from the car If the car has a manual brake system slide the boot to the rear remove the retainer clip amp then remove the retainer push rod amp boot Use the push rod to force the primary piston inward amp remove the snap ring from the groove in the piston bore Then remove the primary piston assembly The repair kit contains a complete new primary piston assembly AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Re
16. the brakes are not overheated Failure of the power brake assembly will noticeably increase the force on the foot pedal required to produce braking Brake too sensitive or Grab If linings are greasy or soaked with oil or brake fluid the brakes tend to grab with slight pedal force Then the linings must be replaced If the brake shoes are out of adjustment grabbing may result A loose braking plate may cause the same condition As the linings contact the drum the backing plate shifts to give hard braking A defective power brake booster can also cause grabbing r lt SCORING ARD SPOTS 7 fe ad ee IAL N eS asi vectes LINING 4 l SHOE SHOE SHOE L1 BELL MOUTHED DRUM SCORED DRUM HARD SPOTS THREADS BARRE ASAI Um SHAPED M x LINING i M if LINING SHOE LL _ jt SHOE f pui Dr eee ELI ee a S BARREL SHAPED DRUM THREADED DRUM Various types of brake drum defects that require drum serv Noisy brakes Brakes become noisy if the brake linings wear so much that the rivets contact the brake drum if the shoes become warped so that the contact with the drum is not uniform if the drum becomes rough amp noisy worm Any of these conditions may cause a squeak or squeal when the brakes are applied Loose parts such as the brake backing plate also may rattle Air in the system If air gets into the hydraulic system poor braking amp spongy ped
17. valve in the wheel cylinder or caliper nearest the master cylinder Install one e id of a short bleeder hose on the bleeder valve Place the other end in a transparent container Open the bleeder valve about 1 V4 turns amp let the fluid drain into the container Close the bleeder valve when the fluid appears clean amp clear Then move on to the bleeder valve next closest to the master cylinder Repeat the procedure at each wheel When flushing is completed check that the master cylinder is filled About 1 quart 0 946L of clean fresh brake fluid is needed to flush the hydraulic system If the hydraulic system is being flushed because of fluid contamination replace all rubber parts in the master cylinder wheel cylinders amp calipers brake hoses amp combination valve Then bleed the hydraulic system Some manufacturers recommend the use of special flushing fluid This fluid s used instead of new brake fluid during the flushing operation Flushing is continued until all the old brake fluid has been flushed out Then the flushing fluid is purged by applying clean dry air through the master cylinder to blow the fluid out Do not use too much air pressure After all flushing fluid is out fill the master cylinder reservoir with new brake fluid Then bleed the system as explained below Filling amp bleeding hydraulic system After flushing the hydraulic system or at any time air may be in the hydraulic system The hydraulic system must be filled and bled
18. For the brakes to operate properly all air must be removed from the system The process of getting rid of any air trapped into the system line or component is called bleeding In the bleeding process brake fluid is forced through the brake line or component that has air in it To bleed the brakes install the pressure bleeder on the master cylinder If the vehicle has a metering valve it must be held in the open position Place the bleeder wrench on the bleeder valve in the wheel cylinder or caliper nearest the master cylinder Install one end of the bleeder hose on the bleeder valve The lower end of the bleeder hose is immersed in clear container partly filled with fresh brake fluid This allows you to see any air bubbles that come out of the line it also prevents any air from being pulled back into the line This can happen if the pressure on the brake fluid is released before the bleeder valve is closed gt A gt a U b ra j x I Is Cos S gt et Y i p a D a gt ge p f j Wc lt X f x Yo Y A an P 40 L A J A 22 iH v 3 B ies LI J eu U gt i T i M gt er Ki i nu I AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL If the master cylinder has bleeder valve and open it about turn Watch the flow of brake fluid from the end of the hose As soon as the bubbles stop amp brake fluid flows from th
19. ILE ENGG
20. KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL DEPARTMENT OF MECHANICAL ENGINEERING LAB MANUAL SUBJECT AUTOMOBILE ENGINEERING B TECH 5 Semester BRANCH ME OF IN ES S gt KCT Gp SNOW KCT COLLEGE OF ENGG amp TECH FATEHGARH Punjab Technical University AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL LIST OF EXPERIMENTS 1 Valve refacing and valve seat grinding and checking for leakage of valves 2 Trouble shooting in cooling system of an automotive vehicle 3 Trouble shooting in the ignition system setting of contact breaker points and spark plug gap 4 Demonstration of sterring system and measurement of steering geometry angles and their impact on vehicle performance 5 Trouble shooting in braking system with specific reference to master cylinder brake shoes overhauling of system and the adjusting of the system and its testing 6 Fault diagnosis in transmission system including clutches gear box assembly and differential T Replacing of ring and studying the method of replacing piston after repair AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 1 OBJECTIVE Valve refacing and valve seat grinding and checking of leakage of valves REFER Tb SPECIE BCA TIC PS bas mn Do not remove more than 0 010 mm j Check for bent stem cE JE md i fi mc We Lim Diameter ELEL TH i WE HEAD F Valve fa
21. RST SECOND GROOVE SYNCHRONIZER lt sau AMA FOM FORK E HIHD EQUITH NEU TAL SYNCHRONIZEF THiRD 9ECOND NEUTRAL isPsgpn SPEED FIRST CLUTCH GEAH GEAR GEAR SPEED AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT Fault diagnosis in gear box Complaint Possible cause Hard shifting a Gearshift linkage out of adjustment into gears b Gearshift linkage needs lubrication c Clutch not disengaging d Excessive clutch pedal free play e Shifter fork bent f Sliding pears or synchronizer tight on shaft splines g Gear teeth battered h Synchronizing unit damaged or springs improperly installed i p tube binding in steering dolumn j End of transmission input shaft binding in crankshafi pilot bushing Transmission sticks in gear Gearshift linkage out of adjustment or disconnected Gearshift linkage needs lubrication Clutch not disengaging Detent balls lockouts stuck Synchronizing unit stuck Incorrect or insufficient lubricant in transmission g Internal shifter component damaged OF MECHANICAL Check or correction Adjust Lubricate Adjust Adjust Replace or straighten Replace defective parts Replace defective gears Replace unit or defective parts install springs properly Correct tube alignment Lubricate replace bushing Adjust reconnect Lubricate Adjust Free lubricate Free replace damaged parts Replace with correct lubricant
22. Wheel zd Cylinder due PEU TERR li 43 11 Rear i Min Brake ur E DRUM BRAKE TROUBLE DIAGNOSIS Brake pedal goes to the floor When the brake pedal goes to the floor there is no pedal reserve Full pedal travel does not produce adequate braking One section might fail but it would be rare for both to fail at the same time It is possible that the driver has continued to operate the vehicle with one section out either the driver may have ignored the warning light or the pressure differential valve or the light may have failed Causes worn linings air in the of failure could be linkage or brake shoes out of adjustment 3 system lack of brake fluid or a defective master cylinder Complaint Possible Cause Check or Correction AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Brake pedal goes to Linkage or shoes out of Adjust floorboard adjustment Lack of brake fluid Add fluid bleed system One brake drags If one brake drags this means that the brake shoes are not moving away from the brake drum when the brakes are released This trouble could be caused by incorrect shoe adjustment or by a clogged brake line which does not release pressure from the wheel cylinder It could also be due to sticking pistons in the wheel cylinder to weak or broken brake shoe return springs or to loose wheel bearings Loose wheel bearings could permit the wheel to wobble so that the brake drum comes in c
23. al will result Air can get into the system if the air vent in the master cylinder cover or cap becomes plugged This may tend to create a partial vacuum in the system on the return stroke of the piston Air could then by pass the rear piston cup amp enters the system Always check the vent amp clean it when the cap or cover is removed Air can also get into hydraulic system if the master cylinder residual checks valve is leaky amp does not maintain a slight pressure in the system A leak could allow air to seep in around the wheel cylinder piston cups Without residual line pressure in the system there would be no pressure holding the cups tight against the cylinder valves AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Probably the most common cause of air in the brake system is insufficient brake fluid in the master cylinder if the brake fluid drops below the compensating port the hydraulic system will draw air in as the piston moves forward when braking Air in the system must be removed by adding brake fluid amp bleeding the system Loss of brake fluid Brake fluid can be lost if master cylinder leaks if the wheel cylinder leaks if the line connections are loose if the line is damaged One possible cause of the wheel cylinder leakage or there is incorrect installation of actuating pin If the pin is cocked the side thrust on the piston may permit leakage past the piston Leakage from other
24. and correct amount Remove transmission to inspect and service shifter parts Gearshift linkage out of adjustment or disconnect On floor shift shift boot suff or shift lever binding Weak lockout springs Bearings or gears worn End play of shaft or gears excessive Synchronizer worn or defective Transmission loose on clutch housing misaligned h Clutch housing migaligned i Pilot bushing in adn hap loose or Transmission a slip out of gears v moa UM r AUTOMOBILE ENGG Adjust Replace boot adjust console to relieve binding Replace Replace Replace worn or loose parts Repair replace Tighten mounting bolts correct alignment o KCT COLLEGE OF ENGG amp TECHNOLOGY misaligned Input shaft retainer loose or broken Broken engine mount Clutch slipping Gear teeth stripped Shifter fork or other linkage part broken Gear or shaft broken Drive key or spline sheared off u Gear worn or tooth broken or chipped Bearings worn or dry Input shaft bearing defective Pilot bushing worn or loose in crank shaft Transmission misalfsned with engine Countershaft worn or bent or thrust plate or washers damaged No power through transmission G Transmission noisy in neutral eo s o a Transmission Clutch friction disk defective noisy in Incorrect or insufficient lubricant gear c Rear main bearing worn or dry d Gears loose on ma
25. causes at the master cylinder or wheel cylinder requires removal amp repair or replacement of the defective parts Possible Cause Check or Correction Loss of brake fluid Master cylinder leaks Repair or replace Wheel cylinder leaks Repair or replace Loose connection damaged Tighten connections replace Brakes do not self adjust Brakes do not self adjust if the self adjusted mechanism has been removed or if the adjustment screw IS stuck or if the adjustment lever does not engage the star wheel or if the adjuster was incorrectly installed Warning light comes on when braking If the warning light comes on when braking it means that there is low pressure in one section of the hydraulic system One of the two braking sections has failed Both sections should be checked so that the trouble can be found amp eliminated It is dangerous to drive in this condition Even though the car slows only half the wheels are being braked AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL BRAKE TESTING amp SERVICE Brake testers There are two types of brake testers the static amp the dynamic One type of static tester has four tread plates amp registering columns To make the tests the car is driven onto the tread plates at a specified speed amp the brakes are applied hard The stopping force at each wheel is registered on the four columns If the readings are too low or are unequal brake service is needed
26. ce angle This line should be parallel with valve head 0 79 Minimum AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL THEORY Each cylinder has two valves an intake and exhaust valve Some high performance engines have four valves per cylinder two intake and two exhaust valves Usually the intake valve is larger than the exhaust valve The reason is that when the intake valve is opened the only force moving air fuel mixture into the cylinder is atmospheric pressure When the exhaust valve is opened the piston is moving up and there is a high pressure driving the exhaust gases out Therefore the intake port must be larger to allow enough air fuel mixture to enter Various types of valves have been used in the past But the valve in general use today is mushroom or poppet valve When the valve is closed it is held on the valve seat by the valve spring PROCEDURE VALVE REFACING If the valves are good enough to reuse is to reface them This requires a valve refacing machine The valve refacer has a grinding wheel a coolant delivery system and a chuck which holds the valve for grinding Set the chuck to grind the valve face at the specified angle This angle must just match the valve seat angle or make an interference angle of to 1 degree Then put the valve Into the chuck and tighten the chuck The valve should be placed in the chuck so that the part of the stem that runs in the valve guide is gri
27. d debris Test Replace conditioner condenser if necessary obstructed Thermostat stuck closed Fan drive clutch Test Replace if necessary defective light defective Exhaust system restricted Causes of slow warm up The most likely cause ofslow warm up is a thermostat that is struck open This allows the coolant to circulate between the engine amp the radiator even though the engine is cold Therefore the engine has to run longer to reach normal operating temperature As a result engine wear is greater because the engine operates cold for a longer time Another possible cause of slow warm up is that the thermostat has been removed Never remove the thermostat amp leave it out of cooling system This does not improve coolant circulation It does delay warm up amp increase engine wear amp sludge formation A quick check for a missing or struck open thermostat can be made by squeezing the upper hose immediately after starting the cold engine Keep your hand away from the fan No coolant flow through the upper hose should be felt if you feel movement the thermostat is missing or open condition Possible Causes Check or Correction Slow warm up Open or missing thermostat Test replace or install necessary AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Defective temperature gauge Check electric Circuit Working safely on Cooling System There are severa
28. e hose in a solid stream close the bleeder valve Repeat these steps at each wheel Then disconnect the pressure bleeder from the master cylinder Check that the master cylinder is filled with brake fluid Wipe up any spilled brake fluid Install the master cylinder Cover the seal amp cover Pump the brake pedal several times Be sure that the firm brake pedal is obtained before moving the vehicle AUTOMOBILE ENGG Pivot KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 6 OBJECTIVE Fault diagnosis in transmission system including clutches gear box assembly amp differential Purpose of clutches The clutch is used in cars with transmission that are shifted by hand It allows the drive to couple uncouple the engine from the transmission Power flows from the engine through the clutch to the transmission amp power train Diagram Pivot Pressure Plate Cx Pressure spring Fly wheel Throwout Bearing A Clutch Pedal Premon ue a KX I Clutch fork l A Cy Release lever Weight Splines on I transmission input shaft FAULT DIAGNOSIS 1 Clutch slips while engaged The slipping clutch generates excessive heat amp may burns causes may be incorrectly linkage of pedal Readjusting the linkage may correct the problem Binding linkage or a broken return spring may prevent full return of the linkage to the engaged position If none of the above is causing the slippage then remove the
29. e of cooling system is to keep the engine at its most efficient operating temperature at all speeds amp under all operating conditions During the combustion of the air fuel mixture in the engine cylinders temperatures of 2200 C or higher may be reached by the burning gases The cylinder walls cylinder head amp pistons absorb some of this heat They in turn must be provided with some means of cooling so that they do not get hot Cylinder wall temperature must not go higher than about 205 C to 260 C Temperature higher than this causes the lubricating oil film to break down amp loose its lubricating properties However the engine operates best at temperatures as close to the limits imposed by oil properties as possible Removing too much heat through cylinder walls amp head lowers the thermal efficiency of the engine Cooling systems are designed to remove about one third 30 35 of the heat produced in the combustion chambers by the burning of the air fuel mixture The engine is very inefficient when cold Therefore the cooling system includes devices that prevent normal cooling action during engine warm up These devices allow the engine parts to reach their normal operating temperatures more quickly This shortens the inefficient cold operating time When the engine reaches its normal operating temperature the cooling system begins to function The cooling system removes excess heat when the engine is hot amp slowly or not at all when the
30. e stop solenoid out of Readjust replace as adjustment or defective necessary Hot spots in combustion Service engine chamber Advance timing Retime ignition Possible causes of electronic system failure ignition system failures can be grouped into three categories These are 1 Loss of energy in primary circuit This could result from a Resistance in the primary circuit due to defective lead bad connections or ignition switch open ignition coil primary winding b Discharged battery or defective alternator c Grounded primary circuit in ignition coil wiring or distributor d Defective ECU or sensor coil circuit to ECU 2 Loss of energy in the secondary circuit due to a Spark plug fouled defective or improperly gapped b Defective high voltage wiring which allows high voltage leakage c High voltage leakage across ignition coil head distributor cap or rotor 3 Out of time ignition due to a Timing not set properly b Centrifugal or vacuum advance defective c Electronic control unit ECU defective SPARK PLUG SERVICE Spark plugs will foul or wear rapidly if they are not of the correct heat range There are spark plug cleaners that sand blast the electrodes and porcelain tip Then after filling the electrodes flat the gap can be reset if the plug is in otherwise good condition However with the cost of labor so high many mechanics recommend replacing spark plugs at periodic intervals instead of cleaning and re
31. engine is cold or warming up Diagram d Cooling system Main Parts of Cooling System Radiator It cools off coolant it is an anti freeze mixture by allowing air passing through the area to dissipate the heat generated by the engine Pump It draws the coolant from the radiator amp pumps it through the engine block cylinder heads heater core amp back to the radiator AUTOMOBILE ENGG J _FILLER NECK Over FLOW Pi Pt KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Freeze plugs It is actually a steel plug designed to seal holes in the engine block amp cylinder head created from the casting process In freezing weather they may push out if there is not enough anti freeze protection Head gasket It seals the major parts of the engine to prevent oil anti freeze mixture and cylinder pressure from mixing together Heater Core It provides heat to the interior of the core by using heat removed from the anti freeze amp flown in by the blower motor may cause stead odd or actual dripping inside the car when it leaks Thermostat It controls the minimum operating temperature of the engine The thermostat is closed when the engine is cold in order to speed the warming up amp opens when normal operating temperature has been reached to allow the antifreeze to pass through the radiator Hoses These connect the other main components of the cooling system Hose manufacturers reco
32. ent collapsing 4 Defective thermostat which does not open normally blocking circulation of coolant If the engine overheats without the radiator becoming normally warm amp if the fan belt is properly tightened Then the thermostat is properly at fault Sometimes on some cars grains of sand from the sand core for the engine block or head may lodge in the thermostat preventing it from opening A thermostat that is installed backwards usually cannot open amp will also cause overheating 5 A loose or worn fan belt will not drive the water pump fast enough The belt should be tightened or replaced Where a pair of belts 1s used both belts should be replaced at the same time not just one belt that appears most worn When you replace only one belt the AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL entire load is on new belt It will wear rapidly When both the belts are replaced with a none matched pair and then each belt will carry half the load 6 Overheating may be caused by after boil This may occur when the coolant starts boil after the engine has been turned off For example after a long hard drive engine has too much heat in it that when the water pump stops circulating coolant it starts to boil Engine Low coolant level Fill as required Check for coolant loss overheating loose fan belts Pressure cap Adjust Test Replace if necessary defective Radiator or air Remove bugs leaves an
33. f grit and dust by centrifugal force After the seat is ground it may too wide Narrow the seat by using upper and lower grinding stones to grind away the upper and lower edges of the seat If the seat is too high grinding with the 150 stone may lower it A steel scale can be used to measure seat width When a new valve is installed it may sit too high above the seat Then grind the seat slightly with a stone of the same seat angle This will lower the valve further into the seat and raised the seat contact on the valve face AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Many shops are now using a hand operated carbide cutter This device takes the place of motor driven stones in refinishing the valve seats Checking of leakage of valves 5 1 Check valve guides for wear Clean replace or and ream for same size valve stem if necessary Or ream for a larger diameter valve stem Check valves and valve seats Clean valve heads and stems on a wire wheel Refinish valve seats and reface valves as necessary Check valve seating Refinishing valve stem ends if necessary Check rocker arms for wear Service or replace as necessary Replace valves and springs in head Check and adjust valve clearance as necessary AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 2 OBJECTIVE Troubleshooting in cooling system of an automotive vehicle Theory The purpos
34. f the drive pinion or the ring gear Incorrect adjustments prevent normal tooth contact and can cause rapid tooth wear and early failure of the differential AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Noise on acceleration Noise that is louder when the car is accelerating probably means there is heavy contact on the heel ends o the gear teeth Noise that is louder when the car is coasting probably means there is heavy toe contact Noise on curves Noise that is heard only when the car 1s going a round a curve the trouble is inside the differential case They can also be due to defective axle bearing During a turn the out side bearing takes an increased load Limited slip differential It requires a special type of lubricant Wrong lubricant can cause the clutch surfaces to grab Remedy is to replace the old lubricant with the right one Part C GEAR BOX It is an assembly of gears and shafts that transmit power from the engine to the drive axle The transmission allows the engine crankshaft to turn fast while the wheels turn slowly The transmission can then change the ratio of crankshaft speed to the car speed as car speed increases Therefore with a three speed transmission the engine crankshaft may turn about four eight or twelve times for each wheel revolution In addition the transmission includes a reverse gear so that the car can be backed The driver selects each of these gear ratios manually FI
35. ifying the engine for increased power output Complaint Possible Cause Check or correction Clutch spins or drags Possible Cause Readjust when disengaged pedal linkage Incorrect adjustment Wrapped friction disk or Replace defective parts pressure plate Loose friction disk facing Replace defective parts Broken engine mount Improper release lever Readjust adjustment 4 Clutch Noise It is noticeable when the engine is idling Noise is heard when the clutch is either engaged or disengaged or during pedal movement Noises heard while the pedal is in motion are probably due to dry dirty linkage pivot points Noise heard when the transmission is in neutral but disappear when the pedal is depressed are transmission noises Noise heard while the clutch is engaged could be due to a friction on disk hub i e loose on clutch shaft or perhaps both it both are excessively worn 5 Clutch Pedal Pulsates Noticeable when a slight force is applied to the clutch pedal with the engine running Pulsations can be felt by the foot as a series of slight pedal movements amp ceases when AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL the pedal force is increased This condition often indicates troubles that must be corrected before serious damage to the clutch results 6 Friction Disk Facings Wear Rapidly Caused by the friction between slippage facings amp the flywheel or pressure plate
36. in shaft c Synchronizers worn or damaged f Speedometer gears worn Gears clash a Synchronizer defective during b Clutch not disengaging pedal free shifting play incorrect c Hydraulic system Hydraulic clutch defective d Idle speed excessive e Pilot bushing binding f Gearshift linkage out of adjustment ee IS 28 lLransmission noisy in reverse damaged b 1 gear on main shaft worn or amaged c AUTOMOBILE ENGG DEPPT OF MECHANICAL Correct alignment i Replace Replace Replace Adjust Replace gears Replace Replace Replace ENS Replace gears Replace lubricant Replace Replace Realign Replace parts worn or damaged Replace Replace of correct lubricant Replace or lubricate with proper amount Replace wgrn parts Replace worn or damaged parts Replace Repair or replace Adjust Check cylinder add fluid et Readjust Replace Adjust _Replace with correct lubrica Replace Replace Counter gear worn or damaged Replace KCT COLLEGE OF ENGG amp TECHNOLOGY Oil leaks d Shift mechanism damaged DEPPT OF MECHANICAL Repair replace defective arts a Foaming due to incorrect lubricant b Oil level too high M AUTOMOBILE ENGG Gaskets broken or missing Oil seals damaged or missing Oil slingers damaged improperly installed or missing Drain plug loose Transmission retainer bolts loose Transmission or exten
37. it 1s too loose or there are other pin or piston defects the pin and piston are replaced as a matched set The piston pin clearance should be no greater then 0 001 inch 0 025 mm Measure the size of each piston with a micrometer The measurement should be made on the piston skirt 90 degrees from the piston pin and 6 mm below the bottom of the oil ring groove This is called the sizing point Compare the piston measurement made at the sizing point with the cylinder diameter This measurement may be made with a telescope gauge and micrometer a cylinder bore gauge or an inside micrometer If the cylinder wall is excessively worn or tapered it will require refinishing When the cylinder is refinished then a new oversize piston must be installed On some engines the manufacturer recommends fitting the pistons by using a long thickness gauge and the piston upside down in the cylinder Use a 0 0025 inch 0 06 mm thickness gauge for used pistons and a 0 002 inch 0 05 mm thickness gauge for new pistons With the bottom of the piston skirt about 1 inch 25 mm below the top of the block the piston should hang not fall free on the thickness gauge If the piston falls through the bore the piston is too small for the cylinder Ring Groove Repair If a piston is in good condition except for excessive ring groove wear the groove can be repaired in some pistons The top ring groove is the groove that wears the most During engine overhaul many
38. l safety hazards one must watch for when working on engine amp the cooling system l Keep your hands away from the moving fan When the engine is running the fan is turning so fast it is a blur But it can mangle your hand and cut off fingers if the hand gets into the fan 2 Never stand in a direct line with the fan A fan blade could break off amp fly out from the engine compartment Any person standing in line with the fan could be injured or killed Before starting the engine examine the fan for cracked or loose blades If you find any damage the fan must be replaced 3 Keep the fingers away from the moving belt amp pulleys The fingers could be pinched amp cut off if they are caught between the belt and the pulley 4 Never attempt to remove the radiator cap from the cooling system of an engine that is near or above its normal operating temperature Releasing the pressure may cause instant boiling of the coolant 5 Coolant is poisonous It can cause serious illness or even death if it is swallowed Always wash your hands thoroughly if you get coolant on them AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 3 OBJECTIVE Trouble shooting in the ignition system setting of contact breaker points and spark plug gap THEORY The basic difference between the contact point and the electronic ignition systems is in the primary circuit The primary circuit on the contact point
39. m the radiator it should either be removed or replaced Oil in the coolant indicates leakage of transmission oil cooler in the outlet tank of the radiator If the leak is at the hose connections the hose should be replaced AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Loss of coolant Pressure cap and gasket Inspect Wash gasket and test Replace only defective if cap will not hold pressure specified External leakage Inspect hose hose connections radiator edges of cooling system gaskets core plugs drain plugs oil cooler lines water pump expansion tank and hoses heater system components Repair or replace as required Internal leakage Check torque of head bolts retorque if necessary Disassembly engine as necessary Check for cracked intake manifold blown head gasket cracked cylinder head or engine Causes of engine overheating The driver may notice that the red light stays on or the temperature gauge registers in the overheating zone Also the driver may complain that the engine boiled over Possible causes of engine overheating include 1 Lower coolant level caused by leakage of coolant 2 Accumulation of rust amp scale in the system which prevents normal circulation of coolant Anti freeze compounds contain additives which tend to prevent theformation of rust amp corrosion 3 Collapsed hoses which prevent normal coolant circulation Suction hoses should contain a spring to prev
40. mmend replacing every 4 years regardless of apparatus because there may be deterioration of the inside of the hose which cannot be seen Fan clutch It senses the temperature of the air coming through the radiator amp either slips or binds up to the pull required amount of air through the radiator Electric cooling fan Most front wheel cars use an electric cooling fan because of the transverse mounted engine It is turned on by a system of sensors amp relays when the engine reaches about 230 F amp stays on until it is cooled to about 200 F Cooling System Trouble Diagnosis Three major cooling system complaints are Loss of Coolant Engine overheating Slow warm up Explanation Causes of loss of coolant Many gaps can be spotted easily for two reasons One the cooling system requires frequent refilling Two the point of gap can be usually found at the top of a telltale stain Dye is added to most anti freeze to make gap detection easier There are two types of coolant gaps External gaps are those where the coolant can drip into the ground These can be seen Typical leak points from hose amp hose connections heater core radiator core amp expansion core plugs freeze plugs in the block amp head Internal leaks can severely damage the engine The coolant may contaminate the oil amp may cause rust A coolant leak into the combustion chamber while the engine is stopped may fill the combustion chamber If the leak is fro
41. move the secondary piston stop screw if so equipped Using the shop air hose apply slight air pressure through the compensating port at the bottom of the reservoir This will force out the secondary piston assembly Remove the piston seals from the secondary piston The outer tube seats check valves amp springs must not be removed from some master cylinders They are permanent parts of the master cylinder However these parts may be removed from other master cylinder Follow the procedure in the manufacturer s service manual Most disk brakes hydraulic systems do not have check valves Clean all parts in brake fluid or brake cleaning solvent only Blow dry with filtered compressed air Blow out all passages amp ports to be sure they are clear If the master cylinder is scored corroded pitted cracked porous or scoring are deep a new master cylinder must be installed To assemble the master cylinder dip all parts except the body into the brake fluid Insert the complete secondary piston assembly with return spring into the master cylinder bore Install the secondary piston stop screw if so equipped Put the primary piston assembly into the bore Depress the primary piston amp install the snap ring in the bore groove Install the push rod boot amp the retainer on the push rod if so equipped Install the push rod assembly into the primary piston make sure the retainer is properly seated amp holding the push rod securely Hydraulic brake
42. nto front amp geometry are a FRONT SUSPENSION HEIGHT This is the distance from some specific point on the body frame or suspension to the ground If suspension is not correct it can affect the angles in the suspension system SUSPENSION HEIGHT AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL b CAMBER Camber is the belting in or out of the front wheels from the vertical when viewed from the front of the vehicle If the top of the wheels tilts out it has positive chamber and if the top of the wheel tilts in it has negative angle Centre line CAMBER A ANGLE made NI EGATIVE CAMBER VERTICAL ANGLE P i a c STEERING AXIS INCLINATION It is also called ball joint inclination on vehicle that have vertical amp a line drawn through the centers of the wall joints when viewed from the front of the vehicle Included angle Camber SAI Steering Axis go Inclination i a POSITIVE ij T CAMBER a TRUE i VERTICAL BALL JOINT lt KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL d CASTER It is the angle formed by the forced or rear ward tilt of the steering axis from vertical when viewed from the side of the wheel The angle is positive when the steering axis tilts backwards Reason for which caster is used 1 To maintain directional stability amp control 2 To increase steering return ability 3 To reduce
43. ontact with the brake shoes even though they are retracted Complaint Possible Cause Check or Correction One brake drags Shoes out of adjustment Adjust Clogged brake line Clear or Replace line Wheel cylinder defective Repair or replace Weak or broken return spring Replace Loose wheel bearing Adjust bearing All brakes drag When all the brakes drag the brake pedal may not have sufficient free travel Then the pistons in the master cylinder do not fully retract This would prevent the lip of the piston cup from clearing the compensating port amp hydraulic pressure would not be relieved as it should be As a result the wheel cylinders would not allow the shoes to retract A similar condition could result if engine oil was added to the system Engine oil will cause the piston cups to swell If they swelled enough they would not clear the compensating ports even with the piston in the fully retracted position A clogged compensating port would have the same result Do not use a wire or drill to clear the port This might produce a burr that would cut the piston cup Instead the port should be cleared with alcohol amp compressed air Clogging of the reservoir vent might also cause dragging brakes by pressurizing the fluid in the reservoir This prevents release of pressure on the fluid in the lines A clogged vent could also cause leakage of air into the system AUTOMOBILE ENGG KCT COLLEGE OF ENGG
44. oubles for e g one test is the spark test Remove a cable from spark plug insert plug extender into the cable end and hold the extender into about 3 8 10mm from the engine block with insulated pliers Crank the engine and check for sparking If no sparking occurs there is trouble in the ignition system If there is good spark the failure to start is probably in the fuel system This test is not recommended for all electronic ignition systems AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Engine cranks normally but fails to start There is no spark during the spark test if the oscilloscope fails to show a secondary voltage pattern there are several possible causes If you get a good spark the ignition primary and secondary circuits probably are ok The failure to start could be due to fouled spark plugs or out of time ignition However failure to start with a good spark is more likely due to trouble in the fuel system Engine cranks normally but No voltage to ignition system Check battery ignition switch fails to start wiring ECU ground lead open loose Repair as needed or corroded Ignition coil open or shorted Test coil replace if defective Damaged armature or sensor Replace damaged part Defective distributor cap or Replace defective part rotor Engine backfires but fails to start This can be caused by ignition or valve timing that is considerably off by faulty or wet distributor cup or
45. pped by the chuck To start the operation align the coolant feed so that it sprays coolant on the rotating valve face Then start the machine Move the lever to carry the valve face across the grinding wheel The first cut should be a light one If this cut removes metal from only one half or one third of the face the valve may not be centered in the chuck Or the valve stem is bent and the valve should be discarded Cuts after the first should remove only enough metal to true the surface and remove pits Do not take heavy cuts If so much metal must be removed that the margin is lost discard the valve Loss of the margin causes the valve to run hot Then it will soon fail Follow the operating instructions of the valve refacer manufacturer Dress the grinding wheel as necessary with the diamond tipped dressing tool As the tool is moved across the rotating face of the grinding wheel the diamond cleans and aligns the grinding face VALVE SEAT GRINDING For effective valve seating and sealing the valve face must be concentric with the valve stem Also the valve guide must be concentric with the valve face In addition the valve face angle must match the valve seat angle or have an interference angle Therefore as a first step in valve seat service the valve guides must be cleaned and serviced Using a dial indicating valve guide gauge to check for wear Movement of the probe in and out of the guide will cause the needle to move if the guide is
46. r grooving are normal amp will not affect braking Some manufacturers recommend never grinding or refacing a scored brake disk Instead installation of a new disk is recommended Refer to the manufacturer s service manual for the proper procedure to follow amp tools to use Brake disks have a discard dimension a number cast into them This dimension is the minimum thickness to which the disk can be refinished If the disk must be refinished to a thinner diameter discard it The disk is too thin for safe use On drum brakes the drum should be inspected for distortion cracks scores roughness or excessive glaze or smoothness Glaze lowers friction amp braking efficiency Drums that are distorted or cracked should be discarded amp new drums installed Light score marks can be removed with fine emery cloth All traces of emery must be removed after smoothing the drum Deeper scores roughness amp glaze can be removed by turning or grinding the drum Many brake drums have their discard diameter cast into them This dimension is the maximum allowable diameter If it 1s necessary to turn or grind the drum to a larger diameter discard it The drum would be too thin for safe use Brake drums should not be refinished to larger than the original diameter by more than 0 060 1 5mm This leaves 0 030 0 76mm left for wear before the discard diameter is reached The diameters of left amp right drums on the same axle should be within 0 010 0 25mm
47. require the reboring of only one or two cylinders When this is done maximum cylinder size difference should not exceed 0 010inch 0 25 mm Aluminum pistons are usually supplied with new piston pins already fitted and packaged in the same box This ensures the proper clearance between the pin and the pin bore in the piston New pistons have a special finish to prevent scuffing during initial start up They must not be buffed with a wire wheel This would remove the finish and increase the chances of scuffing during break in Fitting Piston Pins in Pistons On pistons with piston pin bushings worn bushings may be replaced The new bushings are honed to size to fit the piston pins Piston pin clearance should be no greater then 0 001 inch 0 025 mm Aluminum pistons are supplied with prefitted piston pins as a matched set If a pin set is required However some automotive machine shops hone the piston pin otherwise in good condition Most engine manufacturers do not recommend this Rod And Piston Alignment After the rod and piston have been reassembled but before the rings are installed on the piston alignment should be checked with a rod aligner A V block is held against the piston If the V block does not line up with the faceplate as the piston is swung across it the connecting rod is bent or twisted Some connecting rods can be straightened Check with the manufacturer s service manual before reusing a straightened connecting rod AUTOMOB
48. robably air in the hydraulic system Out of adjustment brake shoes could also cause this Conditions that could allow air to enter the hydraulic system are described Possible Cause Check or Correction Softy or spongy pedal Air in system Add brake fluid bleed dlc Brake shoes of adjustment Poor braking action requiring excessive pedal force A need for excessive pedal force could be caused by improper brake shoe adjustment The use of wrong brake lining could cause the same trouble Sometimes brake linings that have become wet after a hard rain or after driving through water will not provide sufficient friction against the drums However normal braking action is usually restored after the brake linings have dried AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Another possible cause of poor braking action is excessive temperature After the brakes have been applied for long period as in coming down on long hill they begin to overheat This overheating reduces braking effectiveness so that the brakes fade Often if the brakes are all owed to cool braking efficiency is restored However excessive long period braking at high temperature May char the brake linings so that they must be replaced Further this overheating may glaze this rake drum so that it becomes too smooth for effective braking action Then the drum must be ground or turned to remove the glaze Glazing can also take place even though
49. rrect fuel Spark plugs of wrong heat Install correct plugs range Carbon buildup in cylinders Spark plug defective Basically plugs that run too cold will foul plug that run too hot with wear rapidly and burn away This means that the plug gap increases rapidly due to the eroding effect of the spark combined with the excessive temp of the electrodes Possible Causes Causes Check or correction Spark plug defective a J PEi insulator Careless installation install new plug Plug sooty Install hotter plug control high fuel consumption Plug white or grey withllnstall cooler plug blistered insulator Engine diesels or runs on Engines with emission control require a fairly high hot idle speed for best operation This makes run on or dieseling possible Hot spots in the combustion chambers along with enough air fuel mixture getting past a slightly opened throttle valve can keep the engine running The hot spots act as spark plug igniting the mixture in the combustion chamber hot spots could be AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL from hot spark plugs or exhaust valves or from carbon deposits in the combustion chamber Dieseling can damage an engine To prevent dieseling many engines have an idle stop solenoid It closes the throttle valve completely when the ignition switch is turned off Condition Possible Causes Check or correction Engine diesel or runon Idl
50. s considerably off or if ignition crosses firing occurs ignition may result before the intake valve closes This produces a backfire There will be a pop back through the air cleaner Cross firing is spark jump over from one terminal to another or from one high voltage cable to cracked or damaged cable insulation can allow spark jump over Incorrect fuel ratio can also cause backfire Ignition cross firing Check high voltage cables distributor cap and rotor for Faulty ant backfire valve Replace valve Spark plugs of wrong heat Install correct plugs range Defective air injection system Check system Fuel system not Check carburetor supplying proper air fuel ratio Engine overheats Most engine overheating is caused by loss of coolant through leaks in cooling system Other causes include a loose or broken fan belt a defective water pump clogged water jacket in the engine a defective radiator hose and a defective thermostat or fan clutch Late ignition or valve timing lack of engine oil over loading the engine or high speed high altitude or hot climate operation can cause engine overheating Freezing of coolant can cause lack of coolant circulation resulting in local hot spots and boiling Possible Causes Check or correction Engine overheats Late Ignition timing Lack of coolant or other trouble Fill the coolant in cooling system Late valve timing or other Adjust for best performance engine conditions Engine lack
51. s power Many conditions can cause the engine to loose power The wrong ignition timing or any of the conditions discussed in 4 point which cause the engine to miss will reduce engine power As a restricted exhaust system can create excessive backpressure which will prevent normal exhaust from the engine The cylinders will retain the pressure and will not take in a full air fuel charge during the intake strokes AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Possible Causes Check or correction Engine lack power Ignition timing off Retime roe M RR engine oil Use correct viscosity oil Excessive r a resistance Check tires brakes wheel bearing alignments Engine detonates or pings Detonation or pinging is often blamed on the ignition system But there are many other possible causes In the ignition system detonation may be caused by excessively advanced ignition timing faulty advance mechanisms and spark plugs of wrong heat range Fuel with an octane rating too low for the engine can cause pinging or detonation Carbon build up in the engine combustion chambers can result in detonation in two ways First the carbon may glow or become so hot that it can become pre ignition This can result in ping Second the carbon builds up increases the compression ratio This can also cause detonation Possible Causes Check or correction Engine detonation or Improper timing Time ignition pings Wrong fuel Use co
52. sion case cracked Speedometer gear retainer loosc Side cover loose o 20 gt 7 i J k Extension housing sca worn or Tighten Replace Replace with correct lubricant Use proper amount no more Replace Replace Replace correctly Tighten Tighten Tighten Replace KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 7 OBJECTIVE Replacing of ring and studying the method of replacing piston after repair Theory The pistons are slightly smaller there is a gap or clearance between the piston and the cylinder This gap must be filled Otherwise some of the compressed air fuel mixture would leak out through the clearance Also when combustion took place much of the high pressure gas would leak out These leaks would greatly reduce the efficiency of the engine Much of the power would be lost To prevent this piston rings are installed on the pistons Top compression Ring A CEN N _ en INTERMEDIATE COMPRESSIO ICAST IRON Ring side MANUFACTURER S A MARK a E ERE G 1EE PIECE QC TRE NIDTH oed See jIL DRAIN PASSAGES RING FACE Expander From a sliding seal between the piston and the cylinder wall These are called compression rings Scrape off most of the oil that is splashed on the wall so that it does not get up into the combustion chamber where it would burn These are called oil control rings Pis
53. ton Ring Service When an engine is disassembled for service the old piston rings should not be reinstalled Rings that have been used even for very short time usually will not reset properly Selection of new piston rings depends on the condition of the cylinder walls and how they are to be reconditioned If the cylinder walls are only slightly tapered or out of round then the new standard rings selected for an engine may depend on the cylinder reconditioning procedure that has been used Automotive manufacturers generally recommend refinishing the cylinder walls before piston ring installation to Break the Glaze Cylinder walls take on a hard smooth glaze after the engine has been running In many automotive shops this glaze is removed by running a glaze breaker up and down the cylinder a few times before installing new rings The glaze is a good antis cuff surface and will not retard the seating of certain type new rings However the cylinder walls must be reasonably round and in good condition When a cylinder is honed the proper honing job leaves a Crosshatch pattern on the cylinder AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL walls The hone marks should intersect at about a 60 degree angle This leaves the surface needed for oil retention and quick seating of new rings Fitting Piston Rings Piston rings must be fitted to the cylinder and to the rings grooves in the piston Rings come in packaged sets in
54. tubing repair Most hydraulic brake tubing is made of double walled welded steel tubing which is coated to resist rust Only the tubing specified by the automotive manufacturer should be used When replacing a tube used the old tube as a pattern to form a new tube Do not kink the tubing or make sharp bends Brake tubing must be cut off square with a special tube cutter Do not use a jaw type cutter or a hacksaw to cut brake tubing Either of these can distort the tubing amp leave heavy burns that would prevent normal flaring of the tube After the tube has been cut off a flaring tool must be used to double flare the end of the tube FLARING HEAD ADAPTER FIRS LAF t EF x NR n n Z FL rc I pr NG j pe FLARING rl su utsucs FLARE HEAD 1 AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL Flushing Hydraulic The process of removing all the old brake fluid from hydraulic system is called flushing Some car manufacturers recommend flushing the hydraulic system when new parts are installed in it The system must be flushed if there is any indication of brake fluid contamination Signs of dontaminated brake fluid include corroded metal parts and soft or swollen rubber parts To flush the hydraulic system installs the pressure bleeder on the master cylinder If the car has metering valve it must be held in the open position Place the brake bleeder wrench on the bleeder
55. ully from piston surfaces Do not uses a caustic cleaning solution or wire brush These could damage the piston skirt finish You may decide to rein stall the pistons in the engine Therefore do not damage them Use the cleaning method provided in your shop to clean the pistons Clean rings grooves with a clean out tool You can also use the end of a broken piston ring filed to a sharp edge Oil ring slots or holes must be clean so that oil can drain back from them Use a drill of the proper size Do not remove the metal when cleaning the slots or holes Piston Inspection Examine the pistons carefully for wear scuffs scored skirts worn ring grooves and cracks Look for cracks at the ring lands skirts pin bosses and heads Any defects require replacement of the piston with these exceptions cutting the grooves larger and using ring groove spacers can sometimes AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL repair Worn ring grooves Piston skirt wear or collapse reduction in skirt diameter can sometimes be corrected by knurling the piston skirt Using a micrometer to measure piston diameter Check the fit of piston pins in the pistons or piston bushings One way of doing this is to use a small hole gauge to check the piston bushing bores and a micrometer to measure the pin diameter On the type of piston without a bushing in which the oscillates the piston and pin are supplied in matched sets If the f
56. urned to pivot the front wheels Actual steering ratio varies greatly depending on the type of operation Steering ratio called fast or quick steering require much less Steering heel movement to produce the desired steering effort Steering ratio is determined by two factors Steering linkage ratio amp the gear ratio of the steering effort In a rack amp pinion steering system the steering ratio is determined largely by the diameter of the pinion gear The smaller the pinion the higher the steering ratio However there is a limit to how small the pinion can be made AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL EXPERIMENT NO 5 Objective Trouble shooting in braking system with specific reference to master cylinder brake shoes overhauling of system and the adjusting of the system and its testing Theory The construction and operation of the various types of braking system used in automotive vehicles The braking system used most frequently operates hydraulically by pressure applied through a liquid These are the foot operated brakes that the driver normally uses to slow or stop the car They are called the service brakes In addition all cars have a parking brake system which is mechanically operated by a separate foot or hand lever On some trucks and buses the braking system is operated by air pressure This type of brake is an air brake Diagram Fluid Reservoir Wheel Cylinder w
57. y of two sports These are a worm on the end of the steering shaft amp a pitman arm shaft on which there is a gear seek a toothed roller amp a stud TTT m STEERING ARM iHEEL PIVOT lt EN v A Hl AXLE CENTER LINE wf H 1 s CT T R TIE RODS p W _ _ _ 7 l PET Kd l L m 4 i J II a PNE I PITMAN Hh RELAY ROD e IDLER ARM ARM T STEERING GEAR ai FRAME 7 RS hM c xe s ST ERING SHAFT E ua T i GA Front of Car AUTOMOBILE ENGG KCT COLLEGE OF ENGG amp TECHNOLOGY DEPPT OF MECHANICAL ii Rack amp Pinion Steering Gear The rack amp pinion steering gear has become increasingly popular for today s smaller It is simpler more direct acting amp may be straight mechanical or power assisted in operation A complete rack amp pinion steering system set apart from the rest of the cars As steering wheel by shaft are turned are turned the rack moves front side to other On large heavier vehicle this can be a disadvantage In a small car rack amp pinion steering is quick amp easy It provides the maximum amount of road feel as the tires meet irregularities in the road Front of the Car ERING ARN WHEEL PIVOT RA OF Y GEAR TEETH Front End Geometry Front end geometry is the relationship of the angles among the front wheels the front wheel attaching parts amp the ground The various factors that enter i
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