The following information is based on TU series petrol engines, EW series petrol engines and diesel engines
TU series petrol engine
The vehicle is misfiring, and the engine is not performing efficiently
Complete the following compression test in order to identify any problems.
1. Ensure the engine is at normal operating temperature, the battery has been charged, and all spark plugs are removed.
2. Take out the fuel pump fuse from the engine compartment fusebox, this will disable and depressurise the fuel system. Start the engine and run it until it stops.
3. Disconnect the LT wiring connector from the ignition coil module, this will stop the ignition system from working.
4. Screw in a compression tester to the No.1 cylinder spark plug hole.
5. Ensure someone is assisting with the checks, ask them to hold the throttle open fully, as this is being done crank the engine on the starter motor. The compression pressure should be building up to the maximum after one or two revolutions. When it stabilises record the highest number obtained.
6. Repeat for all cylinders.
7. The pressures recorded should all be similar, if there is a difference of two bars between any of the two cylinders there is a fault. Any pressure reading below 10 bars can indicate a cause for concern.
8. If the pressure gradually increases from a low compression then the vehicle is likely to have worn piston rings.
9. If the compression reading is initially low and does not increase, the vehicle is likely to have leaking valves or a blown/cracked head gasket.
10. Low compression readings can also be caused by deposits on the underside of the valve heads.
11. If the pressure readings are low in any cylinder then place a teaspoonful of clean oil into that cylinder through the spark plug hole, and repeat the above test. If the compression pressure improves as a result of the new oil, the vehicle is likely to have bore or piston wear. If the addition of oil does not make any difference to the readings then the vehicle is likely to have a leaking or burnt valve/s or a blown head gasket.
12. If two adjacent cylinders are giving a low reading the vehicle is likely to have a blown head gasket. If coolant is found in the engine oil, this diagnosis will be confirmed.
13. If the pressure readings are unusually high, the vehicle is likely to have high levels of carbon deposits coating the combustion chambers and so will need decarbonising, by removing the cylinder head and cleaning it.
14. Once all tests are finished replace the spark plugs and fuel pump fuse, next connect the ignition coil module wiring connector.
TU Series petrol engine
The cylinder head needs to be removed.
1. Disconnect the battery negative terminal and release the quick-release fitting this will enable the breather assembly to be removed from the cylinder head cover.
2. Next, undo the two retaining nuts and take the washer from each cylinder head cover stud.
3. Remove the cylinder head cover, and the rubber seal. Check the seal ensuring there are no signs of damage or deterioration, if so it will need replacing immediately.
4. Remove the spacer from each stud and take off the oil baffle plate.
5. Remove all traces of oil from the cylinder head and cover mating surfaces by careful cleaning.
6. Place the rubber seal over the edge of the cylinder head cover making sure that it is fitted correctly over the entire length.
7. Put the oil baffle plate back on to the engine, and locate the spacers in their recesses in the baffle plate.
8. Put the cylinder head cover back in the engine, ensuring the rubber seal is not disturbed.
9. Replace the washers and cover retaining nuts tightening them to specific recommendations.
10. Put the breather assembly back on the stub of the cylinder head cover, pushing it until it locks into place.
11. Reconnect the battery negative terminal.
TU Series petrol engine
The timing belt covers need taking out, and the timing belt needs removing and refitting.
1. Disconnect the battery negative terminal. Line up the engine assembly, and valve timing holes, and lock the camshaft sprocket, and the flywheel into position.
2. Unclip the hose that is located at the top of the upper cover.
3. Remove the two retaining bolts located at the front and at the rear, then remove the upper timing cover from the cylinder head.
4. Take off the auxiliary drivebelt through the following instructions:
· Lift the front of the vehicle, and remove the right-hand front road wheel, and the centre section of the wheel arch plastic liner. The plastic liner is held with clips which need to be removed with a forked tool.
· Fit a socket and extension bar to the crankshaft pulley bolt then rotate the crankshaft in order to examine the entire drive-belt.
· Check the drive-belt for any damage such as cracks, splits or fraying. Also check there are no shiny patches, and the belt plies have not separated. If any of the above is found then replace the drive-belt.
5. Take out the upper cover.
6. Loosen the timing belt tensioner pulley retaining nut, as the pulley pivots clockwise it will loosen the tension on the timing belt. Once it is loosened tighten the tensioner pulley retainer nut to hold it.
7. Take the belt off the sprockets and check it for signs of damage, splitting, or oil contamination. If there are any signs of the above then replace the belt immediately. If there are signs of oil contamination, then find the oil leak and rectify it.
8. Clean the timing belt area including the timing belt sprockets.
9. Put the timing belt into the correct position, ensuring it is facing the correct rotational direction. Ensure the belt is fitted over the crankshaft and camshaft sprockets, and the front run is tight. Place the belt over the coolant pump sprocket and tensioner pulley making sure that the belt teeth are centrally placed in the sockets.
10. Loosen the tensioner pulley retaining nut and in the square hole on the front face of the tensioner pulley place a short length of 8.0 mm square bar. Then using the square bar and a spanner turn the pulley anti-clockwise to remove all flexibility from the timing belt, and retighten the nut.
11. To tension the timing belt fit the sensor head of the belt tensioning measuring equipment to the front run of the timing belt, about halfway between the camshaft and crankshaft sprockets.
12. Slacken the tensioner pulley retaining nut using the square bar and spanner and turn the tensioner pulley anti-clockwise until a setting of 44 SEEM units is displayed on the measuring equipment. As soon as this is achieved hold the position and retighten the retaining nut.
13. Remove all tools, and tension measuring equipment from the belt.
14. Move the crankshaft through four complete turns in a clockwise direction using a socket and extension bar on the crankshaft sprocket bolt.
15. Fit the locking tool to the flywheel ensuring that the camshaft sprocket timing hole is aligned.
16. In order to achieve an accurate belt tension the load that is placed on the camshaft lobes from the valve springs and rocker arms needs to be taken away. This needs to be done using a valve rocker contact plate ( a steel plate which is fitted over the rocker arms instead of the cylinder head cover, and held in place using the cylinder head cover retaining nuts.) Directly over the valve stem end of each rocker arm are eight fitted studs and locknuts. The studs are then screwed down until they lift the rocker arms away from the camshaft lobes and then secured using locknuts. This will enable an accurate tension reading to be taken.
17. Take off the cylinder head cover, and loosen the eight rocker arm bolts, fit the contact plate to the cylinder head, and tighten each bolt until the rockers are free from the camshaft lobes, although ensure the bolts are not over tightened.
18. Remove the camshaft sprocket locking tool, but make sure the flywheel locking tool is in the correct place.
19. Place the tension measuring equipment to the belt and turn the tensioner pulley until a setting of between 29 and 33 SEEM units is measured. Keep the pulley in this position, and tighten the retaining nut to the specific torque.
20. Remove all measuring equipment from the belt, the valve rocker contact plate, and the locking tool from the flywheel. Turn the crankshaft through two rotations clockwise, ensuring the camshaft sprocket and flywheel timing holes are realigned, with the locking tools able to be inserted. When this is achieved remove the locking tools.
21. Refit the cylinder head cover, refit the timing belt covers by firstly refit the upper cover making sure it is located with the lower cover, then tighten the bolts and put the hose in its retaining clip on the cover.
22. Next put the lower cover over the timing belt sprocket, and tighten the bolts.
23. Place the pulley at the end of the crankshaft, and tighten the bolts correctly.
24. Reconnect the battery negative terminal.
TU Series Petrol Engine
The timing belt tensioner needs inspecting.
1. Disconnect the battery negative terminal.
2. Position the engine assembly/valve timing holes by:
· Removing the timing belt upper cover (refer to above points)
· Turn the crankshaft until the timing hole in the camshaft sprocket is in line with the corresponding hole in the cylinder head. This can be achieved when looking from the right hand side of the engine and the camshaft sprocket hole is positioned at 2 0’clock. Turning the crankshaft is achieved by using a spanner on the crankshaft sprocket bolt turning in a clockwise position.
· Next in order to lock the crankshaft and camshaft into position insert a 6mm diameter bolt or drill bit through the hole in the front left-hand flange of the cylinder block and into the timing hole in the flywheel. Then insert a 10mm diameter bolt or drill bit through the timing hole in the camshaft sprocket and into the hole in the cylinder head.
3. Take off the timing belt upper and lower covers (refer to above points)
4. Loosen the timing belt tensioner pulley retaining nut, and move the pulley in a clockwise direction using a bar placed in the hole in the pulley hub. Once this has been done tighten the retaining nut.
5. Take the timing belt away from the sprocket, and move the belt away and then take away the locking tool from the camshaft sprocket.
6. Take off the camshaft sprocket retaining bolt and its washer, use a sprocket holding tool to prevent the sprocket from rotating.
7. Take off the sprocket from the end of the camshaft, and take this opportunity to make sure there are no oil leaks from the camshaft oil seal. If there are any leaks then replace it.
8. To check the crankshaft sprocket remove the upper and lower timing belt covers referring to previous points.
9. Next, slacken the timing belt tensioner pulley retaining nut, and move the pulley in a clockwise direction using a bar placed in the hole in the pulley hub. Once this has been done tighten the retaining nut.
10. In order to stop the crankshaft moving while the retaining bolt is loosened, put the vehicle in top gear and ask a helper to depress the brakes.
11. Unscrew the retaining bolt and washer, and take the sprocket off the crankshaft, then fit the locking tool to the flywheel. If the Woodruff key is a loose fit in the crankshaft, remove it and store it with the sprocket. Take this opportunity to make sure there are no oil leaks from the crankshaft oil seal. If there are any leaks then replace it immediately.
12. To work on the tensioner pulley remove the upper and lower timing belt covers referring to previous points.
13. Next, remove the timing belt tensioner pulley retaining nut, and remove the pulley off its mounting stud. Take this opportunity to check the stud to ensure there is no damage. If so then replace it immediately.
14. Make sure all the sprockets are thoroughly cleaned, look out for any signs of damage, if there is any damage present then replace it immediately. Ensure the timing belt is also replaced if the sprockets are replaced.
15. Using a weak solvent clean the tensioner assembly. Ensure the pulley moves correctly with no stiffness, if there is any stiffness or signs of damage then replace the tensioner pulley immediately.
16. To refit the camshaft sprocket, refit the locating peg at the back of the sprocket, then place the sprocket onto the end of the camshaft making sure the locating peg is correctly placed with the cut-out in the camshaft end.
17. Fit the sprocket retaining bolt and washer and tighten to the correct tightness.
18. Ensure the timing hole in the camshaft sprocket is in line with the corresponding hole in the cylinder head (refer to previous points) and fit the locking tool.
19. Fit the timing belt back to the camshaft sprocket making sure that the front run of the belt is not at all loose, and the belt teeth are central in the sprockets.
20. Release the tensioner pulley retaining nut, and using a square – section bar and spanner move the pulley anti-clockwise to stop all free movements, then tighten the nut.
21. Tension the timing belt and fit the timing belt covers (refer to previous points).
22. To refit the crankshaft sprocket make sure that where it was removed find the Woodruff key in the crankshaft end, slide on the flanged spacer ensuring it is in line with the Woodruff key.
23. Next line up the crankshaft sprocket slot with the Woodruff key and slide it onto the end of the crankshaft.
24. Remove the locking tool from the flywheel provisionally, next refit the crankshaft sprocket retaining bolt and washer. Ensure the bolt has been tightened to the correct torque. To stop the crankshaft from rotating ask an assistant to depress the brakes, while in top gear. Fit the locking tool back onto the flywheel.
25. Replace the timing belt onto the crankshaft sprocket making sure that the front run of the belt is tight and the belt teeth are central in the sprockets.
26. To remove all movement from the timing belt loosen the tensioner pullet retaining nut and then with a spanner and square section bar turn the pulley anti-clockwise.
27. Ensure the timing belt is tensioned correctly by following the instructions in the previous points.
28. Replace the timing covers as per previous points.
TU Series Petrol Engine
The camshaft oil seal needs replacing
1. Ensure there are no signs of oil on/in or around the timing belt, if so the timing belt will need replacing as well as the oil seal.
2. Take off the camshaft sprocket according to the previous instructions.
3. Next drill two holes opposite each other in the oil seal and screw in a self tapping screw to each hole. Then pull on both screws and this will release the seal. Remove the seal.
4. Make sure the seal housing is clean, and there are no raised edges or burrs. If there are any raised edges then polish them off, as this could have contributed to the failing of the original oil seal.
5. Ensure the new seal is coated with clean engine oil, push it into position until it sits comfortably on its locating shoulder.
6. Next, making sure you are using a suitable tubular drift like a socket, which will bear only on the outer edge of the seal, the seal lips should face inwards and are not to be damaged during the process.
7. Fit back the camshaft sprocket according to the previous instructions.
TU Series Petrol Engine
The engine is noisy making rattling and/or tapping noises. The engines efficiency is reduced.
This complaint could be due to the valve clearances, and will therefore need checking and adjusting.
1. Ensure the engine is cold.
2. Take off the cylinder head as per previous point.
3. Turn the engine by fitting a socket and extension bar to the crankshaft sprocket or pulley bolt.
4. The valve must be fully closed in order to be checked, and the rocker arm is resting on the heel of the cam. Valve locations can be found from the position of the manifolds. Inlet valves should be set at 0.20 mm, and exhaust valves should be set at 0.40 mm.
5. Turn the crankshaft in the normal direction of rotation, when the exhaust valve for cylinder no.1 is fully open then stop. This will enable you to check the clearances for no. 3 cylinder inlet valve and no. 4 exhaust valve. To check them place a feeler blade which is a correct thickness in between the valve stem and the rocker arm adjusting screw. This should be extremely smooth, however if this is not the case then loosen the adjusting screw locknut, and turn the screw until the smooth insertion is complete. Then ensure the clearance is correct and hold the adjusting screw while tightening the locknut. Recheck the valve clearance and change if necessary.
6. Repeat the above procedure by turning the crankshaft to open exhaust valve cylinder 3 to check clearances for no. 4 inlet valve and no. 2 exhaust valve. Turn the crankshaft to open exhaust valve cylinder 4 to check clearances for no. 2 inlet valve and no. 1 exhaust valve. Turn the crankshaft to open exhaust valve cylinder 2 to check clearances for no. 1 inlet valve and no. 3 exhaust valve.
7. Replace the cylinder head cover as per previous point.
TU Series Petrol Engine
The rocker arm assembly needs removing.
When removing the rocker arms, it is essential that the cylinder is removed in order to remove the rocker arm assembly, however this does mean that the head gasket will need replacing too.
1. Firstly the cylinder head must be removed to do this:
- Disengage the battery negative terminal.
- Drain the cooling system, as per previous instruction.
- Take out the cylinder head cover, as per previous instruction.
- Line up the engine assembly/valve timing holes, and lock the camshaft sprocket and flywheel in position as per previous instruction, remembering not to turn the engine when the locking tools are in place.
- Disengage the exhaust system front pipe from the manifold, and release the lambda sensor wiring to stop it from being pulled under the weight of the exhaust.
- Take out the air cleaner housing and inlet duct assembly as per previous instruction.
- Ensure the fuel system is depressurised and disengage the fuel feed hose from the fuel rail. Make sure all openings are plugged to prevent fuel loss and any dirt going into the system.
- Disengage the accelerator cable.
- In the throttle housing, the fuel injectors and the idle speed stepper motor make sure the significant electrical connectors are disengaged.
- Within the manifold disengage the vacuum servo unit hose, the coolant hose and all other significant hoses.
- Take out the lower timing belt cover as per previous instruction.
- Slacken the timing belt tensioner pulley retaining nut and turn the pulley clockwise with an 8.0 mm square section bar, then retighten the retaining nut to hold in place.
- Disconnect the timing belt from the camshaft sprocket, and place it away from the sprocket making sure it does not bend or twist.
- Disconnect the coolant hoses from the thermostat housing by loosening the retaining clips. The thermostat housing is located on the left hand side of the cylinder head, at the end.
- Press down the retaining clips in order to detach the wiring connectors from the electrical switch and sensors. These are found screwed into the thermostat housing and the cylinder head.
- Disengage the wiring connector from the ignition coil module. The cylinder head may need to be dismantled for over haul, and if this is the case then the ignition coil module must also be removed. (Look for previous instruction on this point).
- Take away the bolt that is used to hold the engine oil dipstick tube to the cylinder head.
- Loosen all 10 cylinder head bolts so that all the bolts are able to be unscrewed by hand, then remove them. Next lift the rocker arm assembly away from the cylinder head.
- Take the cylinder head out of the engine.
2. Move the circlip away from the right hand end of the rocker shaft, but leave the rocker pedestal this will stop it being catapulted of the end of the shaft. Then slide the rest of the components off making sure they all stay in the correct order.
3. Unscrew the cylinder head cover retaining stud from the top of the pedestal using a stud extractor, and remove the stud. Next unscrew the grub screw from the top of the pedestal and take out the rocker shaft.
4. Ensure there are no signs of rubbing or damage on the roller bearing at the camshaft lobe contact point when it is turned. If there is any evidence then replace the worn parts. If scoring damage is shown on the rocker arm roller bearing contact surface then also inspect the corresponding lobe on the camshaft, if they show signs of damage or wear then replace both components.
5. Other components that need checking for signs of wear and damage are the valve clearance adjusting screws, replace if signs of damage or wear are evident. Also check the rocker arm and shaft bearing surfaces show no signs of wear or damage, if so then the damaged rocker arm and damaged shaft need to be replaced.
6. To refit the rocker arm assembly after it has been dismantled take the rocker shaft and fit it to the left-hand pedestal, ensuring the locating hole is in line with the pedestal threaded hole. Next fit the grub screw making sure it is secure, then fit the cylinder head cover mounting stud onto the pedestal again ensuring it is secure.
7. Place clean engine oil onto the shaft, and slide back all components ensuring they are in the correct position (referring to way they were fitted initially). Then compress the right hand pedestal and fit the circlip in the groove on the shaft.
8. Next refit the cylinder head cover as per the following instruction:
- Remove all traces of carbon and gasket from the cylinder head and the cylinder block/crankcase, ensuring no carbon debris enters the oil and water passages. Therefore before starting seal the water, oil and bolt holes with adhesive tape. Using a hard plastic scraper proceed to remove all carbon and gasket.
- Ensure there is no damage or scratches on the mating surfaces of the cylinder block and the cylinder head, if they are minor they could be removed by filing, or more serious ones could be removed by machining, otherwise it will need replacing.
- Make sure the threads of the cylinder head bolt holes in the cylinder block are clean, the bolts do not stick, and any oil or water traces are removed from the bolt holes.
- Check the cylinder head gasket surface for any evidence of distortion if warpage is believed to be evident.
- Ensure all bolts and threads are in a good condition and are cleaned with an appropriate solution. If any are damaged then replace immediately. If any bolt is longer than 175.5 mm from the underside of its head to the end of the bolt all bolts must be replaced.
- Make sure that the two locating dowels are in the correct position at each end of the cylinder block/crankcase surface.
- Place the new gasket on the cylinder block surface with the manufacturer’s markings facing up.
- Using the correct locking tools make sure the flywheel and camshaft sprocket are locked. Then fit the cylinder head assembly onto the block making sure it is lined up with the locating dowels.
- The locating pins need to be in position in the base of each rocker pedestal, once this is achieved place the rocker arm assembly onto the cylinder head.
- Place some grease onto the threads, the underside of the heads of the cylinder head bolts.
- Screw each bolt into position. Then using a torque wrench and socket tighten the cylinder head bolts to the correct setting. Making sure you are working in sequence.
- Then working again in sequence using an angle measuring gauge tighten each bolt through its stage 2 and stage 3 angle.
- Fit the dipstick tube retaining bolt making sure it is correctly tightened.
- Fit the timing belt to the camshaft sprocket making sure that the ‘front run’ of the belt is tight, and is seated correctly. Any looseness in the belt should be on the tensioner pulley side of the belt.
- Pivot the pulley anti clockwise to take all the slack from the timing belt by loosening the tensioner pulley retaining nut, then retighten the nut.
- Tension the belt as per previous instruction.
- Fit the timing belt covers as per previous instruction.
- Connect the wiring connector to the coolant switch/sensor which are located on the left hand end of the cylinder head.
- Connect the coolant hoses to the thermostat housing making sure the retaining clips are secure.
- Fit all wiring, hoses and cables control cables back onto the inlet manifold and fuel system components.
- Connect the accelerator cable.
- Connect the exhaust system front pipe back onto the manifold, and the lambda sensor wiring connector.
- Fit the air cleaner housing and inlet duct.
- Make sure the valve ducts have sufficient clearance as per previous instruction.
- Connect the battery and make sure the cooling system is filled. Refer to previous instruction.
TU Model Petrol Series
The camshaft needs removing.
The camshaft needs to slide out of the right hand side of the cylinder head, therefore the cylinder head will need removing first. Therefore follow the previous instruction to remove the cylinder head.
1. Take out the sprocket locking tool and the camshaft sprocket as per previous instruction.
2. On the left hand end of the cylinder head locate the coolant housing and unbolt it. This will provide access to the retaining bolt, locate the bolt, undo it and remove the camshaft thrust fork.
3. Take out the oil seal out of the right hand end of the cylinder head using a flat screwdriver. Slide out the camshaft. The oil seal needs to be disposed of and a new one replaced.
4. Ensure there are no signs of damage on the camshaft bearing surfaces and cam lobes, if any damage is present the camshaft must be replaced immediately. Also ensure the head bearing surfaces on the camshaft journals and the cylinder head are in good condition. If there are signs of large amounts of wear, the cylinder head will need replacing immediately.
5. Make sure the thrust fork is in good condition, if not then replace immediately.
6. In order to refit the camshaft make sure the cylinder head and camshaft bearing surfaces are clean. Then apply oil to the camshaft bearings and lobes and slide the camshaft back into the cylinder head.
7. At the left hand end of the camshaft is the thrust fork, this needs to be fitted and tightened securely to the correct torque.
8. The coolant housing and cylinder head mating surfaces must be clean and dry. Then using RTV sealant place the coolant housing onto the left hand end of the cylinder head. Tighten all retaining bolts to the required torque in sequence.
9. Place clean engine oil onto the new oil seal and put it in position using a tubular drift, make sure the seal lips face inwards, and are not damaged during fitting.
10. Fit the camshaft sprocket as per previous instruction.
11. Fit the cylinder head cover back on as per previous instruction.
TU Series Petrol Engine
The sump and oil pump need replacing
1. In order to remove the sump it is necessary to begin by disconnecting the battery and raising the front of the vehicle, ensuring the rear wheels are secure.
2. Drain the engine oil sufficiently, and clean the engine oil drain plug before replacing it, ensuring it is tightened to the correct torque. If the vehicle is close to its service renewal then replace the oil filter at the same time as completing the oil change. Fill the engine with new oil.
3. Take off the front pipe of the exhaust system.
4. Remove all the sump nuts and bolts by loosening them first. If the left-hand sump fasteners are difficult to get to, unbolt the flywheel cover plate.
5. Next break the joint of the sump to remove the sump. This may require using a putty knife along the edge until it is released.
6. Check the oil pump pick up/strainer for any damage, and if there are then remove the oil pump.
7. The oil pump can be removed by taking off the three bolts that hold the oil pump in position. Next move the pump sprocket away from the chain. This will release the oil pump.
8. While the pump is removed ensure the sprocket has no signs of damage. If so the pump assembly needs to be replaced as well as the chain and drive sprocket which are located on the crankshaft. When removing the chain and drive sprocket they can be released with the engine after the crankshaft sprocket has be removed, the crankshaft oil seal housing will also need to be unbolted.
9. Also when looking at the oil pump remove the bolts that hold the strainer cover to the pump body. This will release the strainer cover, next remove the relief valve piston and the spring and guide pin.
10. Make sure the pump rotors are clear from damage, if not the entire pump assembly will need to be replaced.
11. Check the relief valve piston is clear from damage as well as the relief valve spring. If there are signs of damage then replace both.
12. Ensure the oil pump strainer is cleaned, again if it shows any sign of damage then replace both the strainer and the cover.
13. Place the relief valve spring, piston and guide pin into position in the strainer cover and fit onto the pump body. Line up the piston with the bore in the pump and secure with the cover retaining bolts ensuring they are correctly tightened.
14. Place the locating dowel into the correct position and connect the pump sprocket to its drive chain. Find the pump on its dowel and secure using the pump retaining bolts ensuring they are correctly tightened.
15. Next replace the sump.