ENGINE CONTENTS
1-1 GENERAL INFORMETION:
STATEMENT ON CLEARANCE AND CARE:
An automobile engine is a combination of many machined, honed, polished and lapped surfaces with tolerances that are measured in the ten thousands of an inch.
When any internal engine parts are surfaced, care and cleanliness are important. A liberal coating of engine oil should be applied to friction areas during assembly to protect and lubricate the surfaces on initial operations.
Throughout this section, it should be understood that proper cleaning and protection of machined surfaces and friction areas is part of the repair procedure. This is considered standard shop practice even if not specifically stated.
Whenever valve train components are removed for surface, they should be retained in order. At the time of installation, they should be installed in the same locations and would the same mating surfaces as when removed.
Battery cables should be disconnected before any major work is performed on the engine, failure to disconnect cables may results in damage to wire harness on other electrical parts.
GENERAL INFORMATION ON ENGINE SERVICES:
The following information on engine surface should be noted carefully. As it's important in preventing damage and in contributing to reliable engine performance.
When raising or supporting the engine for any reason, don't use a jack under the oil pan. Due to the clearance between the oil pan and the oil pump screen. Jacking against the oil pan may cause it to be bent against the pump screen resulting in a damaged oil pick up unit. It should be kept in mind, while working on the engine that the 12-volt electrical system is capable of damaging terminals could possibly be grounded. The ground cable of the battery should be disconnected at the battery.
Any time the carburetor, throttle body injector assembly, or air cleaner is removed, the intake opening should be covered. This will protect against accidental entrance of foreign material which could follow the intake passage into the cylinder and cause extensive damage when the engine is started.
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1-2GENERAL DISCRIBTION:
CYLINDER BLOCK:
The cylinder block is made of cast iron and has 6 cylinders arranged in "V" shape with 3 in each bank. 4 main bearings support the crankshaft which is retained by bearing caps that are machined with the block for proper alignment and clearances. Cylinders are completely encircled by coolant jackets.
CYLINEDER HEAD:
The cast iron cylinder heads features individual in take and exhaust ports for each cylinder. Valve guides are integral, and rocker arms retained on individual pressed studs.
CRANKSHAFT AND BEARINGS:
The crankshaft is cast nodular iron and is supported by 4 main bearings. Main bearings are lubricated from oil holes which intersect the camshaft bearings. The camshaft bearings are fed oil by the left bank oil gallery which is rifle drilled I the block, above the camshaft.
The V-6 engine crankshaft has splayed crankpins for a more even firing and smoother idle. A torsion damper on the forward end of the crankshaft dampens any engine torsional vibrations.
CAMSHAFT AND DRIVE:
The cast iron camshaft is supported by 4 bearings and is chain driven. A steel crankshaft sprocket drives the timing chain which in turn drives the cam through a cast iron sprocket. Cam lobes are grounded, hardened and tapered with the high side toward the rear. This, coupled with a spherical face on the lifter, causes the valve lifters to rotate. Camshaft bearings are lubricated through oil holes which intersect the main oil gallery. The main oil gallery is rifle drilled down the center of the block, above the camshaft.
• The V-6 has only two (2) oil galleries. The main gallery is on the left hand side.
PISTONS AND CONNECTING RODS:
The pistons are made of cast aluminum alloy using two compression rings and one oil control ring. Piston pins are offset 1/16" (1.6mm) toward the thrust side (right hand side) to provide a gradual change in thrust pressure against the cylinder wall as the piston travels its path. Pins are chromium steel and have a floating fit the pistons. They are retained in the connecting rods by a press fit.
Connecting rods are made of forged steel. Full pressure lubrication is directed to the connecting rods by drilled oil passages from the adjacent main bearing journal.
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VALVE TRAIN:
A very simple ball pivot-type train is used. Motion is transmitted from the camshaft through the hydraulic lifter and push rod to the rocker arm. The rocker arm pivots on its ball and transmits the camshaft motion to the valve. The rocker-arm ball is retained by a nut.
HADRAULIC VALVE LIFTERS:
Hydraulic valve lifters are used to keep all parts of the valve train in constant contact. The hydraulic lifter assembly consists of the lifter body, which rides in the cylinder block boss, a plunger, a push rod seat, a metering valve, a plunger spring, a check ball and spring, a check ball retainer and a push rod seat retainer.
When the lifter is riding on the low point of the cam, the plunger spring keeps the plunger and push rod seat in contact with the push rod.
When the lifter body begins to ride up the cam lobe, the check ball cuts off the transfer of oil from the reservoir below the plunger. The plunger and lifter body then rise as a unit, pushing up the push rod and opening the valve.
As the lifter body rides down the side of the cam, the plunger follows with it unit the valve closes. The lifter body continues to follow the cam to its low point, but the plunger spring keeps the plunger in contact with the push rod. The ball check valve will then move off its seat and the lifter reservoir will remain full.
INTAKE MANIFOLD:
The intake manifold is of cast iron or aluminum double level design for efficient fuel distribution. The carburetor pad is centrally located with an Early Fuel Evaporation passage running underneath the pad through which exhaust gases are forced to promote faster fuel vaporization when the engine is cold. An Exhaust Gas Recirculation port is also cast into the manifold for the mixture of exhaust gases with the fuel air mixture.
EXHAUST MANIFOLD:
Two cast iron exhaust manifolds are used to direct exhaust gases from the combustion chambers to the exhaust system. The right hand side manifold receives a heat stove that is used to route heated air to the air cleaner for better fuel vaporization during warm-up.
COMBUSTION CHAMBERS:
Combustion chambers are east to insure uniform shape for all cylinders. Spark plugs are located between the intakes and exhaust valves.
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The Contoured wedge shape of the combustion chamber minimizes the possibility of detonation, facilitates breathing and provides swirling turbulence for smooth, complete combustion.
1-3 ENGINE LUBRICATION:
Full pressure lubrication through a full flow oil filter, is furnished by a gear- type oil pump. The distributor, driven by a helical gear on the camshaft, drives the oil pump. The main oil gallery feeds oil, though drilled passages, to the camshaft and crankshaft to lubricate the bearing. The valve lifter oil gallery feeds the valve lifters which, though hollow push rods, feed the individually mounted rocker arms.
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1-4 ON VEHICLE SERVICE:
ENGINE MOUNTS:
Engine mounts (fig. 3and 4) are the non-adjustable type seldom require service. Broken or deteriorated mounts should be replaced immediately because of the added strain placed on other mounts and drive line components.
INTAKE MANIFOLD:
Removal:
1- Disconnect battery negative cable.
2- Remove air cleaner.
3- Drain cooling system.
4- Remove A.I.R. crossover hose.
5- Remove heater and radiator hoses.
6- Remove alternator upper bracket.
7- Disconnect necessary wires and hoses.
8- Disconnect fuel at carburetor.
9- Connect carburetor linkage.
10- Remove spark plug wires (one side).
11- Remove distributor cap, mark position of rotor, then remove distributor.
12- Remove air conditioning compressor and bracket if equipped.
13- On vehicle equipped with EGR, remove EGR.
14- On vehicles equipped with 4 bb1 carburetor, remove carburetor.
15- Remove manifold bolts.
16- Remove intake manifold.
Installation:
1- Clean gasket and seal surfaces on manifold, block and cylinder heads with degreaser. Remove all RTV that is loose or will cause installation interference.
2- Install gaskets on cylinder heads and place a —" (5mm) bead of RTV, #1052366 or equivalent, on the front and rear ridges of the cylinder caste. Extend the bead 1/2" (13mm) up each cylinder head to seal and retain the manifold side gaskets. Use sealer at water passages.
3- Install manifold and torque blots to specifications in the sequence outlined in figure 5or 6.
4- Install carburetor.
5- Install EGR.
6- Install A/C, compressor and bracket if equipped.
7- Install brake vacuum pipe.
8- Install distributor align rotor with mark and install distributor cap.
9- Install spark plug wires.
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10- Install carburetor linkage.
11- Connect fuel line at carburetor.
12- Connect necessary wires and hoses.
13- Install alternator upper bracket.
14- Install heater and radiator hoses.
15- Install A.I.R. crossover hose.
16- Fill cooling system.
17- Install air cleaner.
18- Start engine, adjust timing and carburetor idle speeds (if necessary) and
check for leaks.
DIPSTICK TUBE:
Removal:
1- Disconnect battery negative cable to prevent possible contact of the dipstick tube with the battery terminal on starter during removal.
2- Remove bolt attaching bracket to engine and remove tube (loose fit).
Installation:
1- Clean tube and apply sealant #1052080 or equivalent, around tube 1/2" below bead.
2- Insert tube in block and rotate into position.
3- Install bolt (with starter brace on top of tube bracket) and connect battery cable.
EXHAUST MANIFOLD:
Removal (right side/left side):
1- Disconnect battery negative cable.
2- Remove air cleaner and heat stove pipe (right side only).
3- Raise vehicle.
4- Disconnect exhaust pipe from manifold and hang exhaust pipe from frame with wire.
5- Lower vehicle.
6- Disconnect spark plug wires, EFE valve vacuum hose and necessary emission control items (right side only).
7- Remove oil dipstick tube retainer on V-6 models from exhaust manifold (right side only).
8- Remove air conditioning compressor and bracket when necessary (left side).
9- Remove power steering bracket (left side).
10- Remove end bolts, then remove center bolts and remove manifold (EFE including right side).
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Installation:
1- Clean mating surfaces on manifold and head, then install manifold in position bolts (finger tight).
2- Toque manifold bolts to specifications.
3- Install power steering bracket (left side).
4- Install air conditioning compressor and bracket when necessary (left side).
5- Install dipstick tube retainer on V-6 models (right side).
6- Install spark plug wires, EFE valve vacuum hose and necessary emission control items (right side).
7- Raise vehicle.
8- Connect exhaust pipe to manifold.
9- Lower vehicle.
10- Install air cleaner.
11- Connect battery negative cable.
12- Adjust necessary belts.
13- Start engine check for leaks.
ROCKER ARM COVER:
Removal:
1- Remove air cleaner.
2- Disconnect necessary vacuum hoses and wires.
3- Remove EGR solenoid and bracket.
4- With 4bbl carburetor, remove EGR.
5- Disconnect spark plug wires.
6- Remove A.I.R. hoses.
7- Remove P.C.V. tube.
8- Remove idle peed solenoid.
9- Remove brake vacuum pipe (left side).
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10- If equipped with air conditioning:
a- Axial compressor: remove upper rear bracket and belt and move compressor aside.
b- Radial four compressors and cruise control: remove compressor.
11- Remove rocker covers.
Installation:
1- When re-installing rocker cover. Install a new gasket if so equipped. If sealing surface is RTV, remove old RTV and replace with a gasket and reinforcement and bolt unit.
2- Reverse removal procedures.
3- Adjust belts.
4- Start engine and check for leaks.
VALVE MECHANISM:
Removal:
1- Remove rocker arm covers us previously outlined.
2- Remove rocker arm nuts, rocker arm balls, rocker arms and push rods. Place rocker arm balls and push rods in a rack to they may be reinstalled in the same locations.
Installation:
• Whenever new rocker arms and/or rocker arm balls are being installed, coat bearing surfaces of rocker arms and rocker arm balls with "Molykote" or its equivalent.
1- Install push rods, be sure push rods seat in lifer socket.
2- Install rocker arms, rocker arm balls and rocker arm nuts. Tighten rocker arm until all lashes is eliminated.
3- Adjust valves when lifter is on base circle of camshaft lobe as follows:
a- Crank engine until mark on torsional damper lies up with center or "O" mark on the timing tab fastened to the crankcase front cover and he engine is in the #1 firing position. This may be determined by placing fingers on the #1 valve as the mark on the damper comes near the "O" mark on the crankcase front cover. If the valves are not moving, the engine is in the #1 firing positions. If the valves move as the mark comes up to the timing tab. The engine is in #6 (#4 on V6) firing position and should be turned over one more time to reach the #1 position.
b- With the engine in the #1 firing position as jut determined, the following valves may be adjusted:
V6-exhaust: 1, 5, 6.
V6-intake: 1, 2, 3.
- 8 -ack out adjusting nut until lash is felt as the push rod then turn in adjusting nut until all lashes is removed. This can be determined by rotating push rod while turning adjusting nut. When play has been removed, turn adjusting nut in one full additional urn (to center lifter plunger).
d- Crank the engine one revolution until the pointer "O" mark and torsional damper mark are again in alignment. This is #6 (#4 on V6) firing position. With the engine in this position the following valves may be adjusted.
V6- Exhaust: 2, 3, 4.
V6- Intake: 4, 5, 6.
4- Install rocker arm covers as previously outlined.
5- Start engine and adjust carburetor idle speed, if needed.
VALVE STEM OIL SEAL AND/OR VALVE SPRING:
Removal:
1- Remove rocker arm cover as previously outlined.
2- Remove spark plug, rocker arm and push rod on the cylinder(s) to be serviced.
3- Install air line adapter tool J-23590 to spark plug port and apply compressed air to hold the valves in place.
4- Using tool J-23590 to compress the valve spring, remove the valve locks, valve cap and valve spring and damper.
5- Remove the valve stem or head oil seal.
Installation:
1- Install valve stem seal over valve stem and seat against head.
2- Set the valve spring and damper, oil shedder and valve cap in place. Compress the spring with J-5892 and install oil seal in the lower groove of the stem, making sure the seal is flat and not twisted. A light coat of oil on the seal will help prevent twisting.
3- Install the valve locks and release the compressor tool making sure the locks seat properly in the upper groove of the valve stem. Grease may be used to hold the locks in place while releasing the compressor tool.
4- Using tool J-23994, apply vacuum to the valve cap to make sure no air leaks past the seal.
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5- Install spark plug and torque to 22lb.ft. (30N.m).
6- Install and adjust valve mechanism as previously outlined.
ROCKER ARM STUDS:
Replacement:
Rocker arm studs that have damaged threads or are loose in cylinder heads should be replaced with new studs available in 0.003" and 0.013" oversize. Studs may be installed after reaming the holes as follows:
1- Remove old stud by placing toll J-5802-1 over the stud. Installing nut and flat washer and removing stud by turning nut.
2- Ream hole for oversize stud using tool J-5715 for 0.003" oversize or toll J-6036 for 0.013" oversize.
Notice: do not attempt to install an oversize stud without reaming stud hole as this could damage the head casting.
3- Coat press-fit area of stud with hypoid axle lubricant. Install new stud, using tool J-6880 as a guide gage should be bottom on head.
VALVE GUIDE BORES:
Valves with oversize stems are available. To ream the valve guide bores for oversize valves use tool set J-5830.
VALVE SEATS:
Reconditioning the valve seats is very important, because the seating of the valves must be perfect for the engine to deliver the power and performance built into it. Another important factor is the cooling of the valve heads. Good contact between each valve and its seat in the head is imperative to insure that the heat in the valve head will be properly carried away.
Several different types of equipment are available for reseating valves seats. The recommendations of the manufacturer of the equipment being used should be carefully followed to attain proper results. Regardless of what type of equipment is used, however, it is essential that valve guide bores be free from carbon or dirt to ensure proper centering of pilot in the guide. Valve seats should be concentric to within 0.002" total indicator reading.
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VALVES:
Valves that are pitted can be refaced to the proper angle, insuring correct relation between the head and stem on a valve refacing mechanism. Valve stem which show excessive wear, or valves that are warped excessively should be replaced. When a valve head which is warped excessively is refaced, a knife edge will be ground on part or all of the valve head due to the amount of metal must be removed to completely reface. Knife edges lead to breakage, burning of pre-ignition due to heat localizing on this knife edge. If the edge of the valve head is less than 1/32" (0.05mm) thick after grinding, replace the valve.
Several different types of equipment are available for refacing valves. The recommendation of the manufacturer of the equipment being used should be carefully followed to attain proper results.
1-5 ENGINE ASSEMBLY:
Removal:
1- Remove hood.
2- Disconnect battery cables at battery.
3- Remove air cleaner.
4- Drain radiator and block.
5- Disconnect radiator and heater hoses and remove radiator and fan shroud.
6- Disconnect wires at:
• Starter solenoid.
• Generator.
• Temperature switch.
• Oil pressure switch.
• Distributor.
7- Disconnect:
• Accelerator linage at inlet manifold.
• Fuel line, from tank, at fuel pump.
• Hoses at fuel vapor storage canister (if applicable).
• Vacuum line to line to power brake unit at manifold, if so equipped.
8- Remove power steering pump and air conditioning compressor and lay aside, if so equipped.
9- Raise vehicle on hoist.
10- Drain crankcase.
11- Disconnect exhaust pipe at manifold and, if so equipped, converter bracket at transmission rear mount.
12- Remove starter.
13- Remove flywheel splash shield or converter housing cover as applicable.
14- On vehicles with automatic transmission, remove converter to flywheel attaching bolt.
15- Remove mount "through" bolts.
16- Remove bell housing bolts.
17- Lower vehicles on hoist.
18- Raise transmission using floor jack.
19- Attach engine lifting devices, raise engine.
20- Remove motor mount to engine brackets.
21- Remove engine assembly.
Installation
1- Position engine assembly in vehicle.
2- Attach motor mount to engine brackets and lower engine in place.
3- Remove engine lifting device.
4- Remove transmission floor jack.
5- Raise vehicle on hoist.
6- Install mount "through" bolts. Torque to specifications.
7- Install bell housing bolts. Torque to specifications.
8- On vehicles with automatic transmissions, install converter to flywheel attaching bolts. Torque to specifications.
9- Install flywheel splash shield of converter housing cover as applicable. Torque attaching bolts to specifications.
10- Install starter.
11- Connect exhaust pipe at manifold and converter bracket at transmission rear mount.
12- Lower vehicle on hoist.
13- Reinstall power steering pump, if o equipped.
14- Connect:
* Accelerator linking at inlet manifold.
* Fuel line, from tank, at fuel pump.
* Hoses at fuel vapor storage canister.
* Vacuum line to power brake unit at manifold, if equipped.
15- Connect wires at:
* Starter solenoid
* Generator
* Temperature switch
* Oil pressure switch
* Distributor
16- Install radiator and fan shroud and reconnect radiator and heater hoses.
17- Fill cooling system.
18- Fill crankcase with oil. See owner's manual for specifications.
19- Install air cleaner.
20- Install hood.
21- Connect battery cables. NOTICE: to avoid possible arcing of battery, connect positive battery cable first.
22- Start engine, check for leaks and check timing.
Crankshaft
The crankshaft can be removed from the engine is dissembled for over haul, as previously outlined, or without complete disassembly.
Removal
1- With the engine removed from the vehicle and the transmission and/ or clutch housing removed from the engine, mount engine in stand and clamp securely.
2- Remove the oil dip stick and oil dip tube.
3- Remove the starting motor, clutch assembly and flywheel.
4- Remove the speak plugs.
5- Remove crankshaft pulley and torsional damper.
6- Remove oil pan and oil pump.
7- Remove crankcase front cover, and if so equipped, remove timing chain and camshaft sprocket.
8- Check the connecting rod caps for cylinder number identification. If necessary, mark them.
9- Remove the connecting rod caps and push the pistons to top of bores.
10- Remove main bearing caps and lift crankshaft out of cylinder block.
11- Remove rear main bearing oil seal and main bearings from cylinder block and main bearing caps.
Cleaning and inspection
1- Wash crankshaft in solvent and dry with compressed air.
2- Measure dimensions of main bearing journals and crankpins with a micrometer for out-of- round, taper or undersize.
3- Check crankshaft for run-out by supporting at the front and rear main bearings journals in "V" blocks and at the front and rear intermediate journal with a dial indicator.
4- Replace or recondition the crankshaft if out of specifications.
Sprocket or gear replacement
• Remove crankshaft sprocket using tool J-5825, install using tool J-5590.
Installation
1- Install rear main bearing oil seal in cylinder block and rear main bearing cap grooves. Install with lip of seal toward front of engine. Where seal has two lips install lip with helix towards front of engine.
2- Lubricating lips of seal with engine oil. Keep oil off parting line surface.
3- Install main bearing in cylinder block and main bearing caps then lubricate bearing surface with engine oil.
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4- Install crankshaft, being careful not to damage bearing surfaces.
5- Recheck bearing clearances using plastigage.
6- Apply a thin coat of brush-on type oil sealing compound to block mating surface and corresponding surface of cap only. Do not allow sealant on crankshaft or seal.
7- Install main bearing caps with arrows pointing toward front of engine.
8- Torque all except rear main bearing cap bolts to specifications. Torque rear main bearing cap bolts to 10-12 Ibs. 14-16 N M then tap end of crankshaft, first rearward then forward with a lead hammer. This will line up rear main bearing and crankshaft thrust surfaces. Retorque all main bearing cap bolts to specifications.
9- Measure crankshaft end play with a feeler gage. Force crankshaft forward and measure clearance between the front of the rear main bearing and the crankshaft thrust surfaces.
10- Install flywheel and torque to specifications. A wood block placed between the crankshaft and cylinder block will prevent crankshaft from rotating.
• Align dowel hole in flywheel with dowel hole in crankshaft. On vehicles equipped with automatic transmission, install flywheel with the converter attaching pads towards transmission.
ENGINE ELECTRICAL SYSTEM
2-1 GENERAL ELECTRICAL SYSTEM DIAGNOSIS:
CHECK:
1- Battery for green indicator.
2- Visual condition of battery cables and connections.
3- If battery needs charging, make generator and battery drain check charge battery and recheck cranking. If trouble has not been found, proceed.
So, remove battery lead from distributor on HEI. Make all voltmeter readings with key start position. Then, measure cranking voltage at battery terminal posts:
1- 9.6volts or more: measure voltage from battery negative terminal to engine block (pos. lead on block.):
a- 0.5volt or more: repair ground cable and connections.
b- Less than 0.5volt: measure voltage at solenoid "B" terminal, clean and tighten connections at starter:
- 9 volts or more; repair starter.
- Less than 9 volts: clean and tighten positive cable connections. If OK, replace cable.
2- Less than 9.6 volts: check battery condition and capacity. If OK, repair starter. If defective, replace battery.
Note: this procedure is designed for use on engines and batteries at room or normal operating temperatures. It also assumes there are no engine defects which would cause cranking problems. To use it under other conditions might result in misdiagnosis.
2-2 CRANKING SYSTEM:
2-2-1 GENERAL DISCRIBTION:
CRANKING CIRCUIT:
The cranking circuit consists of the battery starting motor, ignition switch, and related electrical wiring. These components are connected electrically as shown in figure 2-5 only the starting motor will be covered in this portion.
STARTING MOTOR:
Three types of starter motors are used the first, referred to as the 10MT series. The second type referred to as the 5MT series. The main difference is that the 5MT has the field coils permanently mounted in the frame. Fig. 2-7 shows an exploded view of the 5MT series. Differences in service procedures will be pointed as they occur.
Enclosed shift lever cranking motors have the shift level mechanism and the solenoid plunger enclosed in the drive housing protecting them from exposure to dirt, icing conditions and splash.
In the basic circuit shown in fig. 2-5, the solenoid windings are energized when the switch is closed. The resulting plunger and shift lever movement causes the pinion to engage the engine flywheel ring gear and the solenoid main contacts to close and cranking takes place. When the engine starts, pinion overrun protects the armature from excessive speed until the switch is opened, at which time the return spring causes the pinion to disengage. To prevent excessive overrun, the switch should be opened immediately when the engine starts.
Before removing any unit in a cranking circuit for repair, the following checks should be made:
Battery:
To determine the condition of the battery, follow the testing procedure outlined in the battery section.
Wiring:
Inspect the wiring for damage. Inspect all connections to the cranking motor, solenoid, ignition switch, and battery. Including all ground connections. Clean and tighten all connections as required.
Solenoid and ignition switch:
Inspect all switches to determine their condition.
Starter motor noise:
To correct starter motor noise during starting, use the following procedure:
1- Refer to figure 6D.44 to determine the problem.
2- If the complaint is similar to problem categories 1 or 2 above, correction can be achieved by proper "shimming" as follows:
a- Check flywheel for damage- bent fly wheel, unusual wear, etc.
Problem Cause
1- High pitched whine during cranking (before engine fires) but engine cranks and fires okay.
2- High pitched "whine" after engine fires. As key is being released. Engine cranks and fires okay. This intermittent is often diagnosed as "starter hang. In" or "solenoid weak".
3- A loud "whoop" after engine fires but while the starter is still held engined. Sounds like a siren if the engine is revved while starter is engined.
4- A "rumble", "growl" or in severe cases, a "knock" as the starter is coasting down to a stop after starting the engine. Distance too great between starter pinion and flywheel.
Distance too small between starter pinion and flywheel. Flywheel run out contributes to the intermittent nature.
Most problem cause is a defective clutch. A new clutch will often correct this problem.
Most probable cause is a bent or unbalanced starter armature. A new armature will often correct this problem.
b- Start engine and carefully touch diameter of rotating flywheel ring gear with chock or crayon to show high point of tooth run out after engine is turned off. Turn engine off and rotate flywheel so that the marked teeth are in the area of the starter pinion gear.
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c- Disconnect negative battery cable to prevent inadvertent cranking of engine. Check pinion to flywheel clearance, by using a wire gage of 5mm (.020”) minimum thickness (or diameter). Center the pinion tooth between the flywheel teeth and gage, and not in the corners, where the misleading larger dimension may be observed. If the clearance is under this minimum, shimming the starter away from the flywheel is required.
d- If the clearance is grossly over 5 mm (.020”) (in the vicinity of 1.5 mm (.060”) or more), shimming the starter towards the flywheel is required. (This is generally the problem causing broken flywheel teeth or starter housings). Shimming the starter towards the flywheel can be accomplished by shimming only the outboard starter mounting pad. A shim of .4 mm (.015”) thickness at this location will decrease the clearance by approximately .3 mm (.010”).
If normal starter shims are not available, substitute shims can be improved from plain washers or other suitable material.
Motors:
If the battery, wiring and switches are in satisfactory condition, and the engine is known to be functioning properly, remove the motor and follow the rest procedures outlined below.
Never operate the cranking motor than 30 seconds at a time without pausing to allow it to cool for at least two minutes. Overheating, caused by excessive cranking, will seriously damage the cranking motor.
A general diagnosis is covered in fig. 6D-1 and 6D-2. Once the problem has been traced to the starter, proceed to disassembly test and reassembly illustrations.
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نظام الفرملة والتوقف:
ومن الجدير بالذكر أنه يستخدم في بعض السيارات مقوي فرامل كهربائي بدلا من المقوي الميكانيكي , وذلك حتى لا تتوقف عملية سحب الهواء عند توقف المحرك ,وبالتالي توقف عمل الفرامل .
بقي أخيرا أن نقول أنه يوجد نظام فرملة آخر يستخدم في معظم المركبات الحديثة , هذا النظام يختلف عن النظام الذي أسلفناه في أن النظام الجديد يعتمد على جعل المواد الاحتكاكية تضرب الأقراص الدوارة الأمامية والخلفية عدة ضربات سريعة جدا عند الضغط على دواسة الفرامل , وذلك للسماح للإطارات بالدوران , وبالتالي السماح لجهاز التوجيه بالعمل أثناء عملية الفرملة , بعكس نظام الفرملة الاعتيادي الذي يمنع نظام الفرملة من العمل أثناء عملية الفرملة القوية.
منظومة الوقود:
بقي أخيرا أن نقول أنه تستخدم في بعض السيارات مضخات كهربائية للوقود عوضا عن المضخات الميكانيكية.
ومن الجدير بالذكر أيضا أنه أصبح يستخدم في السيارات الحديثة جهاز تغذية إلكتروني جديد عوضا عن جهاز التغذية التقليدي , هذا الجهاز الجديد يعتمد على أسلوب حقن خليط الهواء والوقود في مجاري السحب باستخدام مضخات ورشاشات يتم التحكم بها إلكترونيا بما يناسب ظروف تشغيل المحرك , مما يعني ضمان تجهيز الخليط بأفضل صورة له ,وبأفضل نسب للهواء والوقود , وبالتالي توفير الوقود.
المحرك:
بقي أن نقول أن المحركات تتمايز عن بعضها البعض في مجموعة من الأمور , أهما سعة المحرك وشكله ونوع الوقود المستخدم فيه.
فمحركات مركبات الشحن الكبيرة مثلا تستخدم مادة السولار كوقود للاحتراق , وذلك بسبب القوة الكبيرة الناتجة عن اشتعاله , أما السيارات الصغيرة فلا تستعمل السولار بسبب بطئ عملية اشتعاله , وإنما تستخدم مادة البنزين بسبب سرعة اشتعاله , أي أن مادة السولار تعطي قوة كبيرة ولكن ببطيء , أما مادة البنزين تعطي قوة أقل ولكن بسرعة أكبر.
ومن الجدير بالذكر أن قوة المحرك تتحدد بسعته وعدد الاسطوانات الموجودة فيه , والمقصود بسعة المحرك هو حجم اسطواناته , وأخيرا فان اكثر أشكال المحركات انتشارا في عالم السيارات هو الشكل الذي تكون فيه الاسطوانات مرتبة على خط واحد , وبالدرجة الثانية تأتي المحركات التي تكون فيها الاسطوانات مرتبة على شكل رقم 7 و التي تكون في العادة ذات سعة و قوة عالية لذلك تستخدم في سيارات السباق الرياضية.
منظومة تبريد وتدفئة المحرك:
ومن الجدير بالذكر أن عملية تدفئة مجاري السحب عملية مهمة جدا , وذلك لأنه في حالة عدم تدفئتها يدخل خليط الاشتعال إلى غرف الاحتراق دون أن يصل إلى درجة حرارة الاشتعال المطلوبة , مما يعني عدم اكتمال عملية احتراقه داخل غرف الاحتراق , وبالتالي تسيل بواقي خليط الاشتعال السائلة إلى خزان الزيت ,اختلاط مادة البنزين بالزيت يفسد لزوجة الزيت مما يعني توقف الزيت عن أداء عمله كمادة لزجة تقلل الاحتكاك بين أجزاء المحرك , وبالتالي يقل عمرك المحرك.
ناهيك عن هذا فان عدم احتراق خليط الاشتعال احتراقا كاملا يؤدي إلى تكون مواد الكربون التي تترسب على صمامات الدخول والخروج , مما يعني تكون طبقة فاصلة بين الصمامات ورأس المحرك , وهذا يؤدي إلى عدم انغلاق الصمامات بشكل محكم , وبالتالي عدم عمل المحرك بشكله الصحيح.
إذا يجب دائما تشغيل السيارة لفترة كافية قبل البدء بالمسير في الظروف الباردة وذلك لتدفئة مجاري السحب بشكل كاف.
الفاصل ومبدل السرعات:
نستنتج من طريقة عمل مبدل السر عات السبب في صدور صوت غريب في بعض الأحيان عند تحريك عتلة مبدل السر عات للحصول على السرعة الخلفية دون عن السر عات الأخرى ,ذلك لأن طريقة الحصول على السرعة العكسية أو الخلفية تختلف عن طريقة الحصول على السر عات الأخرى ,حيث أنه في هذه الحالة يستخدم مسنن ثالث لتعشيق مسننات السرعة الخلفية مع بعضها بدلا من استخدام المعشقات , تداخل هذا المسنن الثالث مع مسننات السرعة الخلفية لا يكون دائما ناجحا ,حيث أنه لا تتطابق دائما رؤوس هذا المسنن مع المسننين الآخرين للسرعة الخلفية , مما يؤدي إلى احتكاك هذا المسنن مع الآخرين حتى تتم عملية التداخل مع بعضهم البعض ,وهذا هو سبب صدور الصوت الغريب سابق الذكر.
منظومة بدأ التشغيل:
في بعض الأحيان تنفذ طاقة البطارية وتصبح غير كافية لإدارة المحرك , لذلك يلجئ الناس إلى دفع السيارة لتشغيلها , فكيف تتم هذه العملية؟؟
يجعل السائق مبدل السر عات في وضعية السرعة الثانية مثلا ,ويدير مفتاح التشغيل حتى يفتح الدارة الكهربائية في المحرك, ويضغط على دواسة الفاصل بشكل مستمر ليفصل مبدل السر عات عن المحرك , ويبدأ شخص أو أكثر بدفع السيارة للأمام حتى تبدأ الإطارات بالدوران بسرعة كافية , هذه الإطارات كما أسلفنا متصلة بمحاور نقل الحركة المتصلة بدورها مع مبدل السر عات , إذا دوران الإطارات يعني دوران العمودين الرئيسيين في مبدل السر عات.
بعد أن تصل السيارة إلى السرعة المناسبة يحرر السائق دواسة الفاصل , مما يؤدي إلى انتقال الحركة الدورانية القادمة من الإطارات إلى حذافة المحرك , مما يعني تدويرها وحصول المحرك على الدورات الابتدائية اللازمة لبدأ عمل المحرك.
