The main problem seems to be in the gaining of evidence and the assembling of a portfolio, so, with this in mind, there are a number of exercises at the end of each section for the student to complete.
The evidence required by the NVQ assessor from the student will be gained gradually and built into a student portfolio. Each completed job sheet suitably signed after the job has been checked should show evidence of what you have done, how you did it and that it was completed to a satisfactory standard. When the student feels confident enough to complete the task alone then he or she may request an assessment.
Examples of assessments are given in the book to show what might be required by the assessor. The text has a number of words and sentences that are highlighted when they first appear in the text. These are mostly key words that will help the student to remember what is essential from the text. Remember the key words and you will be half-way there.
Some of the words used are specific to the motor vehicle and to the NVQ. When oil that is required for lubrication of the camshaft is refitting the rocker cover it is advisable to fit a new readily available. The rocker cover is normally con- gasket. Care should be taken not to overtighten the structed from cast aluminium alloy or a steel pressing.
The type shown in Fig. Oil filler cap is a specialized process which is normally undertaken by firms that specialize in engine reconditioning. The cylinder head is connected to the cylinder block by means of the cylinder head studs, or bolts. The joint between the cylinder head and the cylinder block is sealed by the cylinder head gasket Fig.
When a cylinder head is removed for any purpose the gasket should be replaced and when the head bolts are being tightened it is important that the correct tightening sequence and torque setting are used. Rocker cover. Cylinder heads are cast from cast iron or aluminium alloy. The cylinder head shown in Fig. Figure 4. When performing waterways can be seen. The region around the combus- the check the valve should be raised so that it is just clear tion chambers reaches a high temperature when the of the cylinder head surface.
The valve head is then engine is operating and the waterways play an important pushed sideways to determine the amount of clearance part in preventing overheating. The valve guides and the in the guide, which should not exceed 0. Should valve seats are contained in the cylinder head. In the clearance be found excessive the remedial action aluminium alloy cylinder heads valve inserts are used may take one of two forms: to provide a hard-wearing, heat-resistant valve seat that can be replaced if they become worn or damaged.
Where the guides are part of the cylinder head Valve-seat inserts Fig. New valves with slightly oxygen before being inserted in the cylinder head; this larger stem diameters are then required.
Inlet port. Exhaust port Injector hole. Waterway Exhaust port. In this example of gasket failure, combustion gas has entered the engine cooling system and coolant has entered the combustion chamber, both events causing serious problems that are covered in detail in the chapter on engine cooling systems Chapter Cracks and other flaws Cracks between valve seats and between a valve seat and a waterway sometimes arise when an engine has suffered a cooling system failure.
This type of crack is shown in Fig. Special penetrating dyes have been developed to search for cracks. When the affected part is thoroughly clean the dye is painted on and allowed to dry. After a short period the dye is wiped off and the crack will show up clearly because the dye has entered into it.
Various proprietary brands of this treatment are avail- able. Other methods of crack detection rely on principles of magnetism. In this procedure the object being tested is magnetized in special apparatus e iron filings are then Valve seat insert applied to the affected surface and cracks will show up Fig.
Valve seats 2. Where the guides are an interference fit in the Valve seats should be examined to ensure that the valves cylinder head they may be pressed out and replaced are seating correctly. If a valve seat is worn it may be re- by new ones. In cases of extreme wear the valve seat may need renewing by fitting a valve-seat insert.
The inserts are Valve oil seals an interference fit in the cylinder head as shown in Valve stem oil seals of the type shown in Fig. In some cases the inserts are pressed in and important part in preventing oil from entering the in other cases they are cooled in liquid nitrogen to shrink combustion chamber.
If they are defective they can them prior to fitting to the cylinder head. Cylinder head gasket Combustion chambers In the event of cylinder head gasket failure the gasket The combustion chamber is the space formed by the itself would be examined because this should help to chamber in the cylinder head and the piston crown.
It reveal the cause of failure. There are several probable contains the valve heads and valve seats, and the sparking causes of such failure, but the one shown in Fig. These features are accommodated in a relatively is believed to have been caused by material trapped small space, which is determined by the cylinder bore under the gasket when it was first fitted e some other diameter and the compression ratio.
Cylinder head gasket. A Cylinder block A - locating dowels ER Start at centre and move outwards Fig. Waterway in cylinder head. Crack between combustion space and waterway.
Cutter turned by hand Fig. Cylinder head. Valve stem oil seal Cutter. Each gram of fuel requires approximately 15 grams of air for combustion.
Air is very light and a large volume is Fig. A Valve seat insert. The diameter A is slightly greater than the hole into which it is pressed. This provides the interference fit that keeps Fig. The efficiency unsupercharged engines the air for combustion is with which the chemical energy in the fuel is pushed into the cylinders by the pressure difference converted into power at the flywheel is called the between the atmosphere and that inside the cylinder.
The graph in The amount of air that can be drawn into the Fig. The surrounded by enough air to ensure complete volume of the combustion chamber in relation to the combustion. To obtain the maximum amount of bore and stroke of the engine determines the energy the fuel must burn quickly and completely compression ratio; the higher the compression ratio, and this process is aided, in the combustion chamber, the smaller will be the volume of the combustion by making the air circulate in a process called chamber.
Turbulence is generated by various processes, some of which are discussed in the consideration of various combustion chamber Scavenging designs. The aim of replacing it with the new air fuel charge is called scav- combustion is to convert chemical energy into heat enging. Scavenging is affected by several factors, to raise the pressure of the gas in the cylinder and including the position of the valve ports.
For this process to be efficient there must be as little heat loss as possible through the walls of the combustion Types of combustion chambers chamber. To achieve this result the ratio of the Some of the various types of combustion chambers that surface area of the combustion chamber to its are used in petrol engines are shown in Fig.
It is this factor that has considerable influence on the shape of the chamber. Detonation occurs when a portion of the charge is trapped in a small area of the 0 2 4 6 8 10 12 combustion chamber Fig. The spreading Comp ratio [r] flame front causes a region of high pressure to be created in this small area e this leads to Fig. Pent roof combustion chamber. Hemispherical combustion chamber Four valve combustion chamber Tow valves.
The bath tub chamber The name derives from the shape, which is like that of an upturned bath tub. This type of chamber is widely used in overhead valve engines. The valves are placed Squish region side by side with the inlet and exhaust ports on one side of the cylinder head.
The spark plug is placed on one side of the chamber, which allows for reasonably even flame spread across all regions of the chamber Fig. Squish The pent roof combustion chamber As the piston nears the end of the compression stroke the airefuel mixture is forced out into the main body of the The spark plug can be located in the centre of the combustion chamber, creating turbulence that aids chamber between the valves and this should ensure the spread of flame through the charge Fig.
The design lends itself readily to the twin overhead camshaft arrangement and the The wedge-shaped chamber use of four valves per cylinder, which provides the This type of chamber widens the angle of the inlet and maximum area through which the incoming charge exhaust ports and thus allows relatively unrestricted can enter and the outgoing exhaust gas can leave.
The large area near the spark these topics are dealt with in the chapter on air supply plug provides a wide flame front that aids combustion intake and exhaust systems Chapter The hemispherical combustion chamber cylinder block and the cylinder bores are made in the In this type of chamber the space in the cylinder head is casting.
A hemisphere itself has a low surface area to volume ratio, but it does not Cylinder liners allow a high compression ratio to be used. Most ratio. The spark plug can be situated close to the centre dry liners are an interference fit in the cylinder and of the chamber, thus reducing the chances of detonation they are machined after being pressed in to ensure that occurring. In some cases a type of liner known as a slip fit is used; these are pushed into place by light pressure and then secured Cylinder block and crankcase by means of a flange at the top of the liner that is Figure 4.
In the example shown, the cylinder block Wet liners Fig. An alter- exterior surface of the line is in direct contact with the native to this is to use separate castings for the block and engine coolant. They have a disadvantage that is caused the crankcase. Cast iron is often used to make the by the extra sealing that is required in order to prevent. Cylinder bore Sectional end-view Cylinder block.
Main bearing. Wet liner Wet liner Dry liner Cylinder head. Shims Cylinder block. Water jacket. However, they with, and at right angles to, the crankshaft. The have the advantage that they can be replaced without maximum difference between the standard size and major machining work.
The difference between the When aluminium alloy is used for the cylinder block, in-line reading and the one at right angles is the ovality. The measurements taken may then be compared with Cylinder block condition checks the quoted bore size and excessive wear can be remedied Because piston rings do not reach the top edge of the by reboring or, in the case of minor wear, new piston cylinder bore, when the piston is at the top of its stroke, rings. This means that the cylinders of an Wet liner protrusion for clamping purposes engine wear unevenly from top to bottom of the stroke.
The type of wet liner shown in Fig. In order to obtain the requisite amount gauge has been developed for this purpose Fig. The liner is securely clamped down as shown Once zeroed, the bar gauge is inserted into the cylinder, and the protrusion is measured by the dial gauge e in this as shown in Fig. Measurements are taken in line example the protrusion should be 0. Unworn 1. Thurst side Section of Worn cylinder 2 b a 3. Ridge at top of cylinder that develops d from ring action and side thrust.
Sump at the third measurement. The maximum ovality is: a 0. The taper is: the liner is not fitted correctly. The effect of such a 0. How many degrees of crank rotation are there between firing strokes on a four-cylinder, four- stroke, in-line engine? What steps are necessary when refitting an The crankcase aluminium alloy cylinder head?
The crankcase carries the main bearing supports and in 6. Why are wet cylinder liners normally fitted to some cases it is made as a separate casting from a light aluminium alloy cylinder blocks? How are wet liners alloy, which reduces overall engine weight. Sump 8. What is the reason for producing turbulence in The sump Fig.
It is separated from the crank- head gasket on an engine cooling system? Describe the procedure for checking piston ring must be positioned accurately prior to reassembling the gap. How can the ring gap be increased if it is too sump to the crankcase. When correctly positioned, the small? How does compression ratio affect the thermal in sequence, and finally to the correct torque. Describe how a cylinder head can be examined for probable cracks?
With the aid of a sketch, describe the types of valve seats that are used in aluminium alloy Self-assessment questions cylinder heads. What is the difference between pre-ignition and cylinder at which measurements of diameter are detonation? The measurements Describe some of the possible causes of pre- are taken in line and at right angles to the ignition? What are the symptoms of pre-ignition?
The third Why is an eight-cylinder engine generally smoother measurement is taken at the lowest extent of running than a four-cylinder one?
The terms ovality and taper are When cylinders and pistons are worn, combustion used to describe the condition of the cylinder bore. What happens to this gas Ovality is the difference betweeen a and b, and and how can it affect the lubricating oil in the sump? How can a badly pitted valve seat be repaired? Topics covered in this chapter Firing orders and associated crank arrangements Engine balance Secondary force harmonic balancer Dual mass flywheel. Each time a firing impulse occurs the resulting torque on the crankshaft tends to Cylinder 1 twist it and the effect is noticeable on long crankshafts.
In order to minimize the torsional twist on the crank- Fig. Cylinder number. Table 5. This Fig. In the crank arrangement at the top, pistons gives the two possibilities shown: either it is 1 and 6 are at TDC together; when cylinder 1 fires compression or power. If it is decided to make it can be followed by cylinders 3 or 4 firing. The number 2 cylinder fire next, the firing order will be 1 most common arrangement is to fire number 4 followed by 2.
This means the next cylinder to fire is cylinder and this leads to the firing order of 1e4e number 4 and that is followed by number 3. In the lower of the two diagrams, the crank throws are An alternative firing order for a four-cylinder in-line arranged so that pistons 1 and 6 are at TDC together, engine is 1e3e4e2.
Six-cylinder crankshaft. Alternative crank arrangements. Firing first in the front half of the crankshaft and then as far as possible in the back half minimizes the twisting Vibrations and engine balance of the crankshaft that is the cause of torsional vibrations. If an engine is not properly balanced it will develop vibrations, which cause noise and discomfort to vehicle A V8 crankshaft and firing order occupants and, in time, cause damage to components.
The use of the V8 layout permits the advantages of There are two main areas of the engine where many cylinders to be accommodated in a short space. Crankshaft Nos. Primary forces where m 5 piston mass.
For engine balance purposes 2. Secondary forces. The primary force is given by the first part of the Primary and secondary forces equation, e. Analysis of piston and crank motion shows that at any The secondary force is given by the second part of the point during the stroke a very close approximation of the equation, e. Piston Mass m Four cylinder in-line engine balance Figure 5. The reciprocating parts are identical for each cylinder and the cranks are arranged to provide uniform firing inter- vals and, in most cases, the distances between the Fig.
With this design of engine only. Fs — Secondary Force. In engines single-cylinder engine operating at high speed, the secondary forces can affect the operation of the vehicle and secondary balancers For the purposes of this explanation the rotating parts may be incorporated into the engine design to counter considered are the crankpin and the crankshaft, and any ill effects. In multi-cylinder engines the counterweights that are part of the crank- shaft provide the necessary balancing forces, as shown Secondary force balancer in Fig.
The balance weights are attached to shafts that are driven from the crankshaft see Fig. One shaft rotates in a clockwise direction, the other rotates in an Couples and distance between crank anticlockwise direction; both shafts are driven at twice throws engine speed. Figure 5. The primary forces they are effective at the points required, i.
The cranks are cancel each other out when the secondary force is zero. The couples balance out inside the engine and no effect is felt at the engine Harmonics mountings. Vibrations caused by unbalanced forces in an engine occur at certain engine speeds; the lowest speed at which the vibrations are a problem is called the funda- Balance of individual components mental frequency. Further vibrations will occur at During manufacture great care is taken to ensure that the higher speeds, which are multiples of the fundamental moving parts of the engine are manufactured to fine frequency; these higher speeds are called harmonics tolerances.
In the case of pistons and connecting rods and the harmonic balancer is designed to counteract this also applies to their weight. If, in the course of the effects of the vibrations at these speeds. That is repair, it becomes necessary to replace these units they why the secondary force balancer is often referred to should be checked to ensure that their weights are iden- as a harmonic balancer.
Firing orders and engine balance The balance shafts are driven at twice crankshaft speed. Balance Mass. Counterweights The crankshaft and flywheel are usually balanced as a unit and balance is achieved by drilling holes in appro- priate positions; these can often be seen in the crank web or flywheel. To ensure that the balance is not upset crankshafts are fitted with devices such as dowels that ensure that the flywheel is always correctly fitted to it, as shown in Fig.
Torsional vibration The vibrations associated with the crankshaft and Fig. Crankshaft damper Drive-belt groove. Damper Rubber. Couple Balanced Couples a b. When a cylinder at the front end of a crank- Crankshaft pulley with shaft fires, the torque exerted on the shaft accelerates the built-in damper flywheel and in doing so the crankshaft is twisted slightly.
The periodic application and removal of crank- Fig. The effect is minimized by The vibration damper in the clutch firing cylinders at alternate ends of the engine, but in many cases the vibrations are a problem because they plate can fracture the crankshaft or cause damage in the trans- In a clutch plate of the type shown in Fig.
The springs engines to lessen the effect. This action compresses the springs and converts energy into heat at the small friction Crankshaft damper surface to provide the damping action. The crankshaft torsional vibration damper shown in Fig. The dual mass flywheel The damping effect is provided by the rubber, which Dual mass flywheels are constructed from a number of distorts when vibration attempts to accelerate the separate parts and they are designed to overcome low- drive-belt pulley mass; the distortion of the rubber speed torsional vibration that is a problem in some diesel converts vibrational energy into heat, which is then engine vehicles.
They are called dual mass flywheels passed into the atmosphere and it is this action that because they have two major mass components. One is provides the damping. Springs that allow the hub to move slightly relative to splinded hub. Small friction surface that converts vibration energy into heat. The two masses rotate as Fig. The action of the flywheel removes 4. What is the purpose of the counterweights that vibrational energy from the system and protects the form part of the crankshaft webs?
What is the angle between firing impulses in a six- also reduces noise transmission into the vehicle structure. Examination of Fig. Sketch and describe a crankshaft vibration damper complexity of the device as compared with the relative that makes use of a rubber insert.
What is the purpose of the vibration damper For further information you should look at the LuK that is fitted at the centre of some clutch website www. A certain four-cylinder engine has suffered a number of interesting items. In an attempt to remedy this failure, a cylinder has been bored out and an oversize piston fitted.
What is the likely effect of this repair on engine Self-assessment questions balance? A four-cylinder, in-line, four-stroke engine has a firing 9. What is the reason for firing cylinders at order 1e3e4e2.
When number 1 cylinder is on its alternate ends of the crankshaft, as far as that is power stroke, what stroke is number 3 cylinder on? Make a list of the vehicles that are fitted with dual Provided that the valve timing is correctly set, how mass flywheels. What type of vehicles are most can observation of the order in which inlet valves likely to have dual mass flywheels? How fast, in relation to crankshaft speed, do engine?
Crankpin e taper and ovality Crankshafts are normally made from high-quality The flywheel and its mounting steel by a process known as drop forging. This process Crankshaft oil seals preserves the grain flow in the finished product, which Multi-cylinder engine camshaft is believed to improve its strength.
After forging, the Condition checks on camshaft journals and the crankpins are machined and in the Valve train process the fillet radii are carefully produced because Overhead valve engines OHV they play an important part in the ability of the shaft Checking valve clearance to resist fracture.
Internal drillings transfer oil from the main bearings to the crankpins and big-end bearings. As shown in Fig. Crankshaft Heat treatment The crankshaft is part of the engine where reciprocating motion of the pistons is converted into rotary motion. The bearing surfaces at the journals and crankpins are The main features that are shown in Fig. In carbon steel shafts the hardening is produced by a process called case hardening, or carburizing. In this Web process the shaft is placed at high temperature in the Crankpin presence of carbon-rich material e this results in a layer Main journal of metal that can be made very hard while the remainder of the shaft remains softer and tough.
Nitriding Alloy steels containing elements such as chromium, Counterweight molybdenum and others that are sometimes used in the manufacture of crankshafts, can be hardened by Fig.
Main bearing caps Section of crankshaft Fig. A contains ammonia. The inside of the container is heated thin layer of the tinealuminium alloy is applied to the to about C for 5e25 hours, during which time a thin steel shell as shown in Fig. They are harder than aluminiumetin alloys and they have high fatigue resistance but they are less Because multi-cylinder engine crankshafts are normally able to allow the embedding of small particles, which made in one piece it is necessary to use split bearings means that the journals and crankpins are harder.
The two halves of the split bearing are often referred to as the bearing shells. The actual shell is made from steel sheet approximately 2. These are alloys consisting of copper and lead with a small amount of tin. They are used in turbo-charged and other heavy-duty engines because of their load- Bearing metals bearing capacity. However, they suffer the disadvantage White metal or Babbit metal is named after Isaac Bab- that they are susceptible to corrosive attack from acids bit, who developed it in the early nineteenth century.
To overcome this problem they are The original Babbit metal was made from 50 parts of coated with a thin layer of alloy of lead, tin, and indium tin, 5 of antimony and 1 of copper. Later alloys contain approximately 0. It is quite soft and has low friction when used The bearing shell in the bearing with a hard steel shaft.
The soft metal permits small housing abrasive particles to become embedded below the surface and this reduces shaft wear. Because of the The bearing shells are an interference fit in the housing high stresses imposed on big-end and main bearings, Fig. When assembling new bearings the shell will Babbit bearings are normally used for camshafts. Tinealuminium Alloys of tin and aluminium are commonly used for Bearing cap bearing metal because they are resistant to fatigue and.
Lugs to locate the bearing Steel backing shells in the housing Bearing shells. P E If the diameter is smaller than the lower figure the P 6- crankshaft would be reground so that the journals 1 become slightly smaller. This major repair then necessi- tates the use of undersize bearing shells, which are nor- C A B mally supplied in a range of sizes. On reassembly the clearance between the main journals and the bearing shell may be checked with the aid of a plastic filament called plastigage.
When the crankshaft is resting in the crankcase, the F plastigage material is placed on the journal as shown A. Filament plastigage applied in Fig. The bearing gap is then fitted and tightened B. Shape of filament down. After tightening the bearing gap is removed and after bearing cap is the small gauge is applied.
The width as shown on the removed C. The measuring gauge gives the bearing clearance. The journals can be checked by means is required to provide lubrication. End float may be of an external micrometer and the readings obtained then checked as shown in Fig. Crankshaft end thrust Half washers. Thrust half washers Checking crankshaft end float fitted each side of center main bearing.
The ovality on the crankpin 5 C 2 D 5 Crankpin dimensions Although these variations in diameter of the crankpin The fluctuating inertia forces that the big end is subject are quite small they will, when added to the normal to cause the crankpin to wear unevenly and if these bearing clearance, cause a gap that could lead to forces are excessive they may distort the connecting a loss of oil pressure and bearing failure.
Clearance between the crankpin and the bearing shells can be determined by the use of a plastigage as Connecting rod eye shown in Fig. Prior to checking this clearance the With the bearing shell removed, the bearing cap is diameter of the crankpin should be measured at various assembled to the rod and the bolts are tightened to the points as shown in Fig.
An internal micrometer is then used to record the internal diameter of the connecting rod eye Example at three different points to ascertain that it is not dis- torted. The readings should then be checked against A crankpin is checked for wear as shown in Fig. Crankpin Flywheel A primary function of the flywheel is to store the energy that helps the engine to run smoothly.
On most engines the drive to the transmission takes place via the flywheel Crankshaft web D and the starter ring gear provides the means by which A B C the starter motor starts the engine when required. The rear end of the crankshaft is formed into a flange to which the flywheel is attached. At the centre of this flange is situated a small bearing called the spigot Measure A and B for taper bearing, which supports the first motion shaft of the C and D for ovality gearbox.
Where a friction clutch is used, the gearbox side of the flywheel is machined to act as a friction Fig. Figure 6. Mandrel that aligns clutch plate with the spigot bearing in the end of the crankshaft.
ER K Spigot bearing Flywheel ring gear carries first motion shaft Dowels for locating clutch cover. Camshaft bearings Oil seals As the front end of the crankshaft protrudes outside the Overhead camshaft engine to accommodate a drive pulley and at the rear to On overhead camshaft engines the camshaft is situated accommodate the flywheel, it is necessary to prevent oil in the cylinder head.
Three types of bearing arrangement escaping from the sump and this is achieved by the use are used to support the camshaft: of various types of oil seals.
Two types of crankshaft oil 1. A plain cylindrical bearing that is inserted into the seals are shown in Fig. The internal diameter of the bearing is slightly larger Camshaft than the maximum diameter of the crankshaft to allow the camshaft to be removed from the Camshafts are made from high-grade steel, either by cylinder head. The bearing surface and the 2.
No detachable bearing e the camshaft runs in the wearing surfaces of the cams are heat treated to produce holes machined in the cylinder head material. Split shell-type bearings where the shells are held in End thrust on the camshaft is controlled by a semicir- place by a bearing cap Fig.
Effective lip-type oil seals Overhead valve are normally situated at each end of the camshaft to On an overhead valve engine the camshaft is normally retain the oil that is necessary for the lubrication in over- situated at the side of the engine Fig. The camshaft drive gear shown case it will run in bearings machined into the cylinder in Fig. Engine casting Crank Outer part shaft Lip seal.
Archimedean spiral Fig. Thrust washer Cams. Camshaft drive gear Lip type oil seal. Securing bolt and washer Bearings Dowel Dowel hole Fig. Split shell bearing. Rocker arm Condition checks on camshaft Valve retaining After cleaning, cams and journals should be visually colets Adjustment inspected for signs of wear or damage. The extent of wear on cams and journals can be determined by Valve spring measuring with an external micrometer. An example Pedestal of the relevant dimensions is shown in Fig.
To check for distortion the camshaft is mounted between Valve guide centres on a lathe. A dial test gauge is then mounted so that the stylus rests on the centre bearing of the Valve camshaft; when the camshaft is rotated any distortion Valve soat will be recorded on the gauge. A representative figure Push rod for maximum distortion is approximately 0. In an overhead valve engine of the type shown in Fig.
Inlet valve b 1. Inlet valve 2. Adjustment shims c 2. Exhaust valve 3. Single camshaft 3. Camshaft 4. Rocker arm 4. Rocker arms 5. Rocker shaft 6. Adjustment shims 7. Screwdiver adjusts the tappet clearance. Spanner releases lock nut. Feeler gauge checks the clearance Fig. Overhead camshaft engines The valve train in these engines is shorter than in the Adjustment OHV engine because the camshaft is situated close to shim pad Bucket type the valves, as shown in Fig.
The valve clearance is adjusted by means of a screw and lock nut. In engine Fig. In both cases the valve clearance is adjusted by means of the shims specially designed cotters and a grooved valve stem; that are located at the end of the valve stem. In order to minimize wear, bucket tappets are placed In engine Fig. On clearances are adjusted by means of shims, as shown some engines the valve is made to rotate by the use of in Fig. Check clearance on cylinder number 4 valves Valves rocking on cylinder number 1.
ER K Fig. The procedure for checking valve clearance varies inlet and 6 exhaust. Whichever method inlet and cylinder 5 exhaust. Feeler gauges are selected and inserted between inlet and cylinder 1 exhaust. Should the gap be These two examples show how widely different some too large, the lock nut should be reduced and the adjust- of these procedures can be and how important it is to ment made by means of the screwdriver.
When the check the workshop manual. The following examples show the general procedure for checking valve clearance. An alternative to this procedure that can be used on engines of this type is called the rule of 9.
The valves are numbered from the front of the engine so that the first valve is number 1 and the last one is number 8. Name the parts marked A, B and C in Fig. Self-assessment questions What is the purpose of the hole at D? What is the purpose of the seals shown in Fig. It is believed that the valve seal?
What steps are necessary to ensure that the piston Describe: ring is placed at right angles to the cylinder when a The valve spring defects that may have caused checking the ring gap Fig. It is recommended the problem. A Exhaust valve seal B Inlet valve seal. ER K. Name each of the components marked 1e6 in K Fig. A cam belt tensioning device of the type Fig. The illustrations have been selected to give the maximum amount of support when learning about new topics.
We advise students to attempt the learning tasks when they have completed the related section of their training and education. This book is based on many years of teaching and helping students and apprentices who have gone on to become successful and valued mechanics.
Some of them have become owners of their own motor vehicle workshops, each in turn has appreciated the training that was given to them in their early years. Our hope is that this book will enable a wider variety of people to achieve their hopes and ambitions. In order to take account of feedback from practicing teachers and to allow for developments in technology, education and training this 2nd edition includes coverage of developments such as; variable value timing, on board diagnostics, computer controlled systems etc.
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