9. PERIODIC MAINTENANCE SERVICE A vehicle which is systematically inspected, readjusted, re-lubricated and serviced at specified intervals always remains in good working condition and is safe to use. Periodic maintenance includes carrying out certain checks, adjustments or replacements after fixed intervals of time or kilometers run by the car in order to keep it in prefect and safe condition.
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9.1
Objectives After going through this lesson, you will be able to: Attend to all the periodic maintenance services so that the engine remains in efficient working condition and gives high performance and good mileage.
Introduction
The parts and system components deteriorate with age and their useful life can be enhanced with periodic maintenance. Every item has specified intervals at which it needs to be attended to. This is the subject of study for this lesson. During periodic maintenance, we check in particular: • levels of engine oil and coolant, • nuts and bolts for looseness, • hoses and pipes for leakage and damage, and • components of the ignition system for proper setting, etc.
9.2
Periodic Maintenance Schedule
The basic maintenance services of a car are met through free and regular services. Free services are provided to new cars with the first one being provided when the car has covered 500 km to 800 km. The second service is provided when the car has covered 2,000 Km to 2,500 km and the third one is provided when the car has covered 5,000 km to 5,500 km. Thereafter, the car must be taken for regular service every 5,000 km. Fig. 9.1: Maintenance schedule.
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During each maintenance operations service, one must check and adjust: Water pump drive belt. Engine oil filter.
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Camshaft timing belt. Ignition timing after the third free service and then at every 10,000 km. Engine oil API SC rating at every 5,000 km. Engine oil API SF rating at every 10,000 km. Oil filter at time of oil change or after every 10,000 km of operation. Fuel filter at every 20,000 km. Coolant at every 20,000 km. Spark plugs at every 10,000 km. Distributor breaker points at every 10,000 km.
Self-check Questions 1. 2. 3. 4. 5. 6.
Why is periodic maintenance necessary? List the checks done in periodic maintenance. Give the schedule of free and regular services. Engine oil API SC rating is changed at every ___________. Engine oil API SF rating is changed at every ___________. Oil filter is changed at time of _____________ or after every ____________ of operation.
9.3 • • •
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Water Pump Belt Disconnect the negative lead of the battery at the battery terminal. Inspect the belt for any cracks, cuts, deformations, wear and cleanliness. Check the belt tension under thumb pressure. A deflection of 6-9 mm is satisfactory. Adjust the belt by adjusting the Fig. 9.2: Checking belt tension. alternator position to the required specification, if it is too tight or too loose. o Loosen the adjusting bolt of the alternator mounting stay. o Pull the alternator to provide the specified tension in the V belt. o Tighten the adjusting bolt of the alternator mounting stay. Tighten the alternator bracket and mounting bolts. If the belt needs replacement, o Loosen the alternator adjusting and pivot bolts. o Move the alternator inwards. o Replace the belt and move the alternator outward, adjusting the belt to specified tension. o Tighten the alternator adjusting and pivot bolts. Connect the negative lead of the battery to the terminal at the battery. It is important that all adjustments are done when the engine is not running.
9.4
Valve Lash
Valve lash (tappet clearance) is the clearance between the rocker arm adjusting screw and the valve stem. • •
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Remove the engine head cover. Check the tappet clearance in the inlet and exhaust valves using a feeler gauge and adjust it if required.
Tappet Clearance Adjustment Rotate the flywheel to match the TDC mark with the pointer mounted on the block, and cylinder No. 1 is in compression. Adjust the tappet clearance of cylinder No. 1 which is towards the crank pulley side. Tighten the adjusting screws with the help of a screw driver and set a gap of 0.130.18 mm when cold or 0.23-0.28 mm when hot, using a feeler gauge. Tighten the lock nut with an open end spanner.
Fig. 9.3: Valve adjusting screw and lock nut.
To adjust the tappet clearance of cylinder No. 3, counting from the crank pulley side, rotate the flywheel 240O. Similarly, the tappet clearance for cylinder No. 2 can be adjusted after rotating by another 240O. Note that the tappet clearance is adjusted in the order of the firing order.
9.6
Engine Bolts
All the cylinder head bolts must be tightened to a specified torque of 5.5-6.0 mkg and at the time of retightening, each bolt must be tightened to the same torque to provide an equal pressure throughout the gasket surface. The tightening sequences given in the manuals should be followed. The cylinder head cover bolts are tightened to a specified torque of 0.4-0.5 mkg while the inlet and exhaust manifold nuts are retightened to a specified torque of 1.8-2.3 mkg.
Self-check Questions 7. Crankshaft V-belt should show a deflection of ________ under thumb pressure. 8. Belt tension can be adjusted by ___________________________. 9. Valve lash is the clearance between the _______________ and the ______________. 10. Tappet clearance is adjusted using a _____________. 11. Tappet clearance is adjusted to between ____________ when engine is cold and ______________ when it is hot.
12. Tappet clearance of cylinder No. 1 is adjusted when _______________ and __________________________. 13. Cylinder head bolts are tightened to a torque of _________________.
9.7 • • • •
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9.8 • • • • •
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Engine Oil Filter Loosen and remove the oil filter using the filter wrench. Apply engine oil on the ‘O’ ring of the new filter. Pour some fresh oil into the filter. Screw on the new filter by hand until the ‘O’ ring on the filter contacts the mounting Fig. 9.4: Oil filter. surface. Tighten the oil filter with the filter wrench till it contacts the mounting surface firmly. Start the engine to check for any leakage of oil.
Engine Oil Before draining the engine oil, check the engine for any leakage of oil. If a leakage is detected at any place, correct it. Drain the engine oil by removing the drain plug from the oil pan. Wipe the drain plug clean after draining the engine oil and re-install it. Tighten the drain plug securely to a tightening torque of 3-4 mkg. Replenish the engine oil with Servo Super 20W-40 (SC rating) or equivalent until the level is brought to between full and low marks on the dipstick, which is about 2.5 litres. Start the engine and run it for two to three minutes. Stop the engine and wait for three minutes and check the level again. Add more oil if necessary to bring the level between the full and low level marks on the dipstick.
The complete lubrication system requires about 3.0 liters of oil. It is important to change the oil filter with every oil change.
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Engine Coolant Remove the radiator cap when the engine is cool. Disconnect the radiator outlet water hose from its pipe. Remove the reservoir tank and the drain. Connect the radiator outlet water hose to the water pipe and tighten the clamp. Reinstall the reservoir. Fill the radiator with three litres of coolant. Run the engine for two to three minutes at idle speed to remove air from the cooling system.
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Stop the engine and check the level of the coolant in the radiator. Add more coolant if needed to maintain the level upto the throat of the radiator. Reinstall the cap. Add coolant to the reservoir upto its full level mark.
The reservoir has a low level and a full level mark and its capacity is about 0.6 liters. The radiator cap should never be opened when the engine is hot, to avoid the danger of being burnt by the hot fluid and steam that may blow out under pressure.
Fig. 9.5: Coolant reservoir.
9.10 Cooling System Hoses • •
Visually check the system hoses for any leakage, damage or cracks. Check the clamps for tightness.
In case of any evidence of damage or crack, the hoses and the clamps should be replaced.
9.11 Exhaust Pipes and Mountings When the car is raised for other services or for periodic maintenance, the exhaust system should also be checked. • • • • •
Check the rubber mountings for any damage or deterioration. Check the exhaust system for any leakage or loose connections or missing bolts. Tighten the bolts and nuts at tightening torque of 3.5-5.0 mkg. Check the surrounding area along the exhaust system for any damage. Ensure that the exhaust system components have enough clearance from under the body to avoid any over heating of the metal sheet. Correct this if needed.
Self-check Questions 14. Engine oil is applied on the ‘O’ ring of the new filter before fitment. State whether True/False. 15. Fresh oil is poured into the filter before fitment. State whether True/False. 16. ________________________ oil is filled in the engine. 17. Oil level is checked with _____________. 18. Oil level is checked _____________ after the engine is stopped. 19. The radiator cap is removed when the engine is _________.
9.12 Ignition Wiring (High Tension Cords) • • • •
Inspect the high tension cords for any cracks. Check that the connections of the cords are intact. Measure the resistance of the high tension cords by using a circuit tester. Replace the cords which have indications of any deterioration.
Fig. 9.6: Measuring resistance of high tension cords.
9.13 Distributor Cap and Rotor • • • •
Inspect the distributor cap and the rubber caps for cracks. Inspect the central electrode and the terminal for any wear. Inspect the rotor for cracks and its electrode for wear. Replace or clean any component that is found defective.
9.14 Spark Plug and Distributor Circuit Breaker Point 9.14.1 Spark Plug •
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Disconnect the high tension cords from the spark plug by pulling on the spark plug caps. Loosen and remove the plugs using a spark plug wrench. Check the gap using a wire gauge and if needed, correct it using a special tool.
Fig. 9.7: Correcting spark plug gap.
When replacing the plugs, it must be ensured that the new plugs used are for the specified heat range and size. • •
Install the new spark plugs and tighten them to a torque of 2.0-3.0 mkg. Connect the high tension cords to the spark plugs.
9.14.2 Distributor Circuit Breaker (CB) Point • •
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Remove the distributor cap after disconnecting the cords. Replace the contact breaker point and apply a small amount of grease to the breaker arm heel. Adjust the breaker point gap to the required specification of 0.4-0.5 mm.
Fig. 9.8: Adjusting CB point gap.
For adjusting the gap, o Rotate the ignition cam so that the rubbing block pushes on the breaker arm and the gap is at its widest opening. o Loosen the screw holding the breaker plate to the base plate. o Shift the breaker plate in the slot to increase or to decrease the gap. o Measure the gap with the help of a feeler gauge and tighten the screw after the specified gap has been set. The distributor housing clamp bolt should never be loosened when adjusting the breaker point gap.
9.15 Ignition Timing After the breaker point gap has been set, the ignition timing is checked using the timing light. • •
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Clamp the light to the high tension cord No. 1. Start the engine and run it at a speed not higher than 900 - 950 RPM. Direct the light to the inspection window in the transmission case. If the 7° timing mark on fly Fig. 9.9: Using stroboscopic light to check the ignition timing. wheel appears aligned to the pointer then ignition is properly timed. If the marks do not match, adjust the timing as follows: o Recheck the breaker point gap to be sure that it is between 0.4 to 0.5 mm. o Loosen the distributor clamp bolt and turn the distributor housing in place to advance or retard the timing. The timing is advanced by turning the housing counterclockwise and retarded by turning it clockwise. Check the timing with the timing light after repositioning the housing. If necessary, repeat the last step. Tighten the clamp bolt.
9.16 Timing Advancer Action 9.16.1 Centrifugal Advance • • •
Remove the distributor cap. Turn the rotor in the clockwise direction using a finger and then release the rotor. Check whether or not the rotor returns counterclockwise smoothly by spring force.
9.16.2 Vacuum Advance • • • •
Remove the distributor cap. Disconnect the vacuum hose from the carburetor Apply vacuum by sucking from the vacuum hose and release it. Check the breaker plate for smooth operation. If it does not operate smoothly, replace the vacuum advancer.
9.17 Air Filter Element 9.17.1 Inspection and Cleaning The air cleaner element should be cleaned in all periodic maintenance checks. • • •
Open the air cleaner case by removing the clips and remove the air cleaner element. Fig. 9.10: Using compressed air to clean After removing the element, check it visually the air cleaner element. for any damage. Clean the element by blowing compressed air from the inside.
You will be able to see dust being blown out. The compressed air should never be blown from the outside of the element as this will lead to the dust particles being embedded in the element. • • •
Clean the air cleaner case and cap and reinstall the element. While fixing the cap, match the arrow mark on cap with the mark on the case. Clamp the cap onto the case with the clips.
9.17.2 Replacement • • • •
Remove the air cleaner cap. Take the cleaner element out from the case. Install a new cleaner element. Install the air cleaner cap, aligning the two arrow marks on the assembly.
9.18 Carburetor Choke • • • • •
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Disconnect the choke wire. Check if the choke wire is free or jammed. Check the choke valve for free movement and lubricate it by putting few drops of oil. Visually inspect the outer core of clutch wire for cracks or damage. If the choke wire is hard to move, put few drops of oil on it and pull and push the wire till it becomes free. Fix the clutch wire.
Fig. 9.11: Lubricating the choke wire.
9.19 Fuel Tank Cap and Fuel Lines •
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Visually inspect the fuel lines and connections for evidence of fuel leakage, hose cracking or damage. Ensure that all the fuel line clamps are secure. Repair the leaky joints. Fig. 9.12: Inspecting fuel tank gasket. Replace the hoses that are suspected for cracks and early failure. Remove the petrol tank cap and inspect the rubber gasket fixed in the cap. Replace the old gasket if necessary. Restore the cap on the petrol tank.
9.20 Fuel Filter The fuel filter unit should be replaced at regular scheduled intervals. The fuel filter is located at the front part of the fuel tank. It is removed from the car by disconnecting inlet and outlet hoses from the filter. • •
Position the new filter in place. Connect the inlet and outlet hoses. The top connection on the filter is for the outlet and the lower connection for the inlet hose.
The fuel filter change procedure must be performed in a well ventilated area that is away from open flames.
9.21 Engine Idle Speed and Idle Mixture An external tachometer is needed to check idle speed. All the checks must be done after ensuring that the air cleaner is properly cleaned, the choke valve is in full open position and the ignition timing and the engine tappet clearance are within the specifications. • •
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Adjust the idle speed to 1000 RPM by readjusting the idle speed screw. With the engine idling at 1000 RPM, turn the idle mixture screw to the right or to the left and set it where the highest engine speed is obtained. This is the best idle position. Repeat the two steps above again and then adjust the idle speed to 1000 RPM with the idle speed adjusting screw. Readjust the engine idle speed to 900 RPM by turning the idle mixture screw slowly in the clockwise direction.
9.22 Emission Control System •
Check crankcase ventilation hose for leaks and cracks.
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If there are any defects, replace the hose.
9.23 Positive Crankcase Ventilation (PCV) Valve • • •
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Disconnect the PCV hoses. Run the engine at idle speed. Place your thumb over end of the disconnected PCV hose to check the vacuum. If there is no vacuum, check for a hose or valve being clogged or choked. Replace as necessary. Stop the engine and check the PCV for sticking. With the engine stopped, remove the PCV hose and connect a new hose to PCV valve. Blow air into new hose and check whether the air flows with difficulty from the cylinder head side to the intake manifold side. o If so, the valve is in the closed position. o If the air flows without difficulty, the valve is stuck in the open position. Replace the PCV valve. Connect the PCV hose securely.
It is important never to suck air through the PCV valve. The petroleum products inside the valve and the fuel vapours inside the intake manifold are harmful.
9.24 Fuel Vapour Storage System and Hoses • •
Visually inspect the hoses for cracks, damage or cuts, making sure that all clamps are securely positioned. If any hose is found to be defective, replace it.
Self-check Questions 20. Spark plug gap is checked with a ___________. 21. Breaker point gap is adjusted between ______________. 22. Base (idle) rpm is ____________. 23. Base timing is ____. 24. On sucking at the vacuum hose, the breaker plate should rotate otherwise the vacuum advancer should be replaced. State whether True/False. 25. The air cleaner element is cleaned by ____________________________.
9.25 Assignments 9.25.1 Class Assignment 1. Discuss the importance of periodic maintenance and the checks and adjustments done during periodic maintenance.
9.25.2 Home Assignment 1. Make a list of all scheduled / periodic checks that have to be performed in case of a four stroke engine. Also identify the interval / change frequency.
9.26 Summing Up In this lesson, we studied the importance of periodic service. We understood the checks that have to be performed and also outlined the change / inspection interval. Free services prescribed by the car manufacturer are an important element of extending the life of a car. This is because the wear of parts is accelerated during the running--in period, hence replacement of oils and checks and adjustment of clearances gains importance. After a period, wear and tear stabilizes and performance can be maintained by regular service checks and adjustments. It is here that periodic maintenance plays an important part. Hence it should not be neglected. A small investment of time and money goes a long way in extending the life of the vehicle.
9.27 Possible Answers to Self-check Questions 1. The parts and systems deteriorate with age and their useful life can be enhanced with periodic maintenance. A vehicle which is systematically inspected, readjusted, re-lubricated and serviced at specified intervals always remains in good working condition and is safe to use. 2. Levels of engine oil and coolant; Nuts and bolts for looseness; Hoses and pipes for leakage and damage, and Components of the ignition system for proper setting. 3. Free services are provided to new cars with the first one being provided when the car has covered 500 km to 800 km. The second service is provided when the car has covered 2,000 Km to 2,500 km and the third one is provided when the car has covered 5,000 km to 5,500 km. Thereafter, the car must be taken for regular service every 5,000 km. 4. 5,000 km 5. 10,000 km 6. oil change, 10,000 km 7. 6-9 mm 8. repositioning the alternator 9. rocker arm adjusting screw, valve stem tip 10. feeler gauge 11. 0.13-0.18 mm, .23-0.28 mm 12. it is in compression, TDC mark on flywheel is aligned 13. 5.5-6.0 mkg 14. True 15. True 16. Servo Super 20W-40 (SC rating) 17. dipstick 18. 3-5 minutes 19. cool
9.28 Terminal Questions 1. 2. 3. 4. 5. 6. 7.
What is tappet clearance and why is it necessary? How is it done? Describe the procedure of replacing engine oil. Describe the procedure of adjusting the breaker point gap. Describe the procedure of adjusting the ignition timing. Describe the procedure of cleaning the air cleaner. Describe the procedure of adjusting the idle mixture and idle speed. Describe the procedure of checking the PCV system.
9.29 References 1. Maruti 800 Service Manual.
9.30 Glossary Centrifugal advance
A device found on the distributor which, through the action of centrifugal force on two weights, advances or retards the ignition spark to correspond with changes in engine speed and load.
Contact breaker points
A mechanically operating switch in the distributor with two metal contact points (usually made of silver, platinum, or tungsten) that open and close due to ignition cam.
Free service
Service which is done free of cost by the dealer in the initial period after purchase of vehicle so that running-in is trouble-free which also increases the life of the vehicle .
High tension Lead
The wire which goes from the ignition coil to the distributor and the wires which go from the distributor to each of the spark plugs. They convey high voltage but carry very little current.
Idle mixture
The mixture of air and fuel which is fed to the cylinders at idle speed.
Idle speed
This is the speed of the engine with the following conditions: The transmission is in neutral (or park in automatic transmissions), the engine is fully warmed up, the choke butterfly is fully open, and there is no extra accessories in operation (i.e., air conditioner, radio, lights). Also called idling speed. At this speed the engine produces enough power to run smoothly and complete all the operations.
Ignition cam
A cam with as many lobes on it as number of cylinders to operate the contact breaker points for
sparking. PCV system
Positive crankcase ventilation system. A system which prevents crankcase vapors from being discharged directly into the atmosphere.
Periodic maintenance service
Service which is done periodically (e.g. at 5000 km or 6 monthly interval etc.) to restore the various systems of the vehicle to optimum performance.
Spark plug wrench
A tool for removing and installing spark plugs. It comes in a variety of shapes, e.g., with swivel or Thandle, and many have rubber inserts to prevent damage to the fragile insulating material.
Tachometer
A device used to indicate the speed of the engine in rpm. The tachometer is mounted on or near the dashboard (some even appear in a heads-up display on the windshield). It helps the driver to know the optimum rpm for changing gears on manual transmissions. A tachometer is also a diagnostic device which a mechanic uses to determine idle speed and other carburetor and running settings. Also called a rev counter.
Timing light
A stroboscopic unit that is connected to the secondary circuit to produce flashes of light in unison with the firing of No. 1 spark plug. By directing these flashes of light on the whirling timing marks the marks appear to stand still. By adjusting the distributor, the timing marks may be properly aligned, thus setting the timing. Xenon timing lights have the advantage over neon lights because they increase visibility in daylight.
Vacuum advance
A mechanism on the side of the distributor that automatically varies the instant at which the spark occurs as a function of intake manifold vacuum. Vacuum advance provides the additional advance that is needed when the engine is operating at part throttle. At part throttle less air-fuel mixture gets into the cylinders and the mixture takes longer to burn after it is ignited. Because the mixture burns more slowly, the piston will be past top dead center and moving down before the mixture has a chance to burn and produce high power. As a result much of the power in the fuel will be lost. The vacuum advance mechanism consists of a flexible springloaded diaphragm connected by a linkage to the
breaker plate on which the points are mounted. The sealed side of the diaphragm is connected by a tube to the carburetor. The throttle valve is below the vacuum passage in the carburetor air horn so there is no vacuum advance when the engine is idling because the throttle is closed. However, when the throttle is partly open, intake manifold vacuum pulls the diaphragm in and this causes the breaker plate to rotate a few degrees and advance the timing. With wide-open throttle there is very little vacuum in the intake manifold so there will be no vacuum advance. In most instances the vacuum advance is disconnected before checking the timing and point gap. Vacuum hose
A pipe which connects the intake manifold to the vacuum advancer.
Valve clearance
The distance between the small end of the valve stem and the rocker arm or valve lifter. This gap is necessary to compensate for expansion due to heat (and also to ensure proper fitment).
Valve lash
Valve tappet clearance or total clearance in the valve operating train with cam follower on camshaft base circle.