GM Prizm/Nova 1985-1993 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



1985 - 88 VIN Code 4 Engine

See Figures 1 through 6

All wires and hoses should be labeled at the time of removal. The amount of time saved during reassembly makes the extra effort well worthwhile.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system and save the coolant in clean containers.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the air cleaner assembly.
  2.  
  3. Elevate and safely support the vehicle on jackstands.
  4.  
  5. Drain the engine oil.
  6.  


CAUTION
Used motor oil may cause skin cancer if repeatedly left in contact with the skin for prolonged periods. Although this is unlikely unless you handle oil on a daily basis, it is wise to thoroughly wash your hands with soap and water immediately after handling used motor oil.

  1. Disconnect the exhaust pipe from the exhaust manifold and the exhaust bracket from the engine.
  2.  
  3. Disconnect the hose at the converter pipe.
  4.  
  5. If equipped with power steering, loosen the pivot bolt at the power steering pump.
  6.  
  7. Lower the vehicle to the ground.
  8.  
  9. Disconnect the accelerator and throttle control cables at the carburetor and bracket.
  10.  
  11. Label and remove the wiring at the cowl, the oxygen sensor and the distributor.
  12.  
  13. Label and disconnect the vacuum hoses.
  14.  
  15. Disconnect the fuel hoses at the fuel pump.
  16.  
  17. Remove the upper radiator hose from the engine.
  18.  
  19. Remove the water outlet assembly from the head. Remove the heater hose.
  20.  
  21. If equipped with power steering, remove the adjusting bracket.
  22.  
  23. Label and disconnect the vacuum hoses and spark plug wires at the distributor. Remove the distributor.
  24.  
  25. Remove the PCV from the valve cover.
  26.  
  27. Reposition or disconnect the wiring harness running along the head.
  28.  
  29. Remove the upper timing belt cover bolts.
  30.  
  31. Remove the valve cover and its gasket.
  32.  



Click image to see an enlarged view

Fig. Fig. 1: Cylinder head exploded view - 1985-88 VIN Code 4 engine



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Fig. Fig. 2: Cylinder head exploded view - 1988 VIN Code 5, 1990 VIN Code 5 and 1991-92 VIN Code 6 engines



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Fig. Fig. 3: Cylinder head exploded view - 1989-90 VIN Code 6 and 1991-92 VIN Code 5 engines

  1. Remove the water pump pulley bolts and the pulley.
  2.  
  3. Remove the alternator belt.
  4.  
  5. Matchmark the camshaft pulley and the cylinder head so that the marks can be realigned during reinstallation. With chalk or crayon, mark the timing belt with an arrow showing the direction of rotation and mark the belt-to-pulley alignment as well.
  6.  



Click image to see an enlarged view

Fig. Fig. 4: Mark the timing belt rotation before removal - 1985-88 VIN Code 4 engine

  1. Loosen the bolt holding the timing belt idler pulley; move the idler to release tension on the belt and snug the bolt to hold the idler in the loosened position.
  2.  
  3. Carefully pull or slide the timing belt off the cam pulley. Do not crimp the belt and do not force it off the pulley with tools.
  4.  
  5. Loosen and remove the head bolts gradually, in 3 passes and in the order shown in the illustration.
  6.  


WARNING
Head warpage or cracking can occur if the correct removal procedure is not followed.



Click image to see an enlarged view

Fig. Fig. 5: Cylinder head loosening sequence - 1985-88 VIN Code 4 engine

  1. Remove the cylinder head with the manifolds and carburetor attached. If the head is difficult to lift off, gently pry it up with a suitable tool placed between the head and the projection on the block. If prying is needed, be careful not to score or gouge the mating surfaces of the head and/or the block.
  2.  
  3. Keeping the head upright, place it on wooden blocks on the workbench. If the head is to receive further work, the various external components will need to be removed. If the head is not to be worked on, the mating surface must be cleaned of all gasket and sealant material before reinstallation.
  4.  
  5. Clean the engine block mating surface of all gasket and sealant material. Use plastic or wooden scrapers so as not gouge the metal. Remove all traces of liquids from the surface and clean out the bolt holes.
  6.  

To install:
  1. Install the new head gasket on the block with the sealer facing upwards.
  2.  
  3. Place the head in position and make sure it is properly seated and aligned.
  4.  
  5. Install and tighten the cylinder head bolts. Tighten then gradually, evenly, and in 3 passes in the order shown. On the first pass, tighten all the bolts to 14 ft. lbs. On the second pass the bolts are tightened to 30 ft. lbs. and on the last pass the bolts are tightened to their final setting of 43 ft. lbs.
  6.  


WARNING
Failure to follow this procedure exactly may cause either premature gasket failure or head damage.



Click image to see an enlarged view

Fig. Fig. 6: Cylinder head torque sequence - 1985-88 VIN Code 4 engine

  1. Align the camshaft pulley mark(s) made during disassembly with the marks on the head and or block.
  2.  
  3. Install the timing belt onto the cam pulley, being careful not to allow the belt to become mispositioned on the lower (crank) pulley. Handle the belt carefully and avoid getting fluids or lubricants on the belt.
  4.  
  5. Loosen the holding bolt for the timing belt idler pulley and allow it to tension the belt.
  6.  
  7. Turn the crankshaft clockwise through at least 2 full revolutions; finish the rotation by aligning the timing marks at TDC. Double check that the small triangular mark on the cam pulley is at the top and pointing up.
  8.  
  9. Tighten the bolt for the timing belt idler pulley to 27 ft. lbs.
  10.  
  11. Using a belt tension gauge such as GM-23600-B or equivalent, check the timing belt tension. Correct tension is 0.6mm at 4.4 lbs.
  12.  
  13. If the head was disassembled during the repair, adjust the valves at this time. If the head was not disassembled, the valves need not be adjusted.
  14.  
  15. Install the valve cover and the upper timing cover.
  16.  
  17. Install the water pump pulley and bolts; install the alternator belt and adjust it to the correct tension.
  18.  
  19. Correctly position or reconnect the wiring harness running along the head.
  20.  
  21. Install the PCV valve in the valve cover.
  22.  
  23. Correctly install the distributor and connect the wiring, vacuum lines and spark plug wires.
  24.  
  25. Install the power steering adjusting bracket if so equipped.
  26.  
  27. Install the heater hose, the water outlet at the head and connect the upper radiator hose to the engine.
  28.  
  29. Connect the fuel lines to the fuel pump.
  30.  
  31. Observing the labels made earlier, connect the vacuum hoses to their ports. Make sure the hoses fit securely on the fittings and are not crimped or twisted.
  32.  
  33. Connect the wiring at the cowl, the oxygen sensor and the distributor.
  34.  
  35. Connect the accelerator and throttle control cables at the bracket and at the carburetor.
  36.  
  37. Safely raise and support the vehicle.
  38.  
  39. If equipped with power steering, tighten the pivot bolt for the pump.
  40.  
  41. Connect the hose at the converter pipe.
  42.  
  43. Connect the exhaust bracket to the engine and connect the exhaust pipe to the manifold.
  44.  
  45. Lower the vehicle to the ground.
  46.  
  47. Install the air cleaner assembly.
  48.  
  49. Add the correct amount of fresh engine oil.
  50.  
  51. Confirm that the radiator and engine draincocks are closed and fill the cooling system with the correct amount of coolant. Install the radiator cap.
  52.  
  53. Double check all installation items, paying particular attention to loose hoses or hanging wires, untightened nuts, poor routing of hoses and wires (too tight or rubbing) and tools left in the engine area.
  54.  
  55. Connect the negative battery cable.
  56.  
  57. Start the engine; during the warm up period, check carefully for any signs of fluid leaks or engine overheating.
  58.  
  59. When the engine has reached normal operating temperature, check the ignition timing and adjust the idle speed as necessary.
  60.  

1988 VIN Code 5 Engine

See Figures 2 and 7 through 12

All wires and hoses should be labeled at the time of removal. The amount of time saved during reassembly makes the extra effort well worthwhile.

  1. Disconnect the negative battery cable
  2.  
  3. Open the draincocks on the engine and radiator. Collect the coolant in clean containers.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the air cleaner assembly.
  2.  
  3. Disconnect the cruise control cable if so equipped.
  4.  
  5. Disconnect the throttle cable from the throttle linkage.
  6.  
  7. Remove the heater hose from the cylinder head rear cover.
  8.  
  9. Label and remove the vacuum hoses from the throttle body.
  10.  
  11. If equipped with cruise control, remove the actuator and bracket assembly.
  12.  
  13. Remove the ignition coil.
  14.  
  15. Remove the upper radiator hose from the cylinder head and the radiator.
  16.  
  17. Remove the brake booster vacuum hose.
  18.  
  19. Remove the PCV hose.
  20.  
  21. Unbolt and remove as a unit the fuel pressure regulator.
  22.  
  23. Unbolt and remove the EGR valve with the lines attached.
  24.  
  25. Remove the cold start injector hose.
  26.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the No. 1 fuel line.
  2.  
  3. Remove the first and second water bypass hoses from the auxiliary air valve.
  4.  
  5. Remove the vacuum pipe and the cylinder head rear cover.
  6.  
  7. Remove, disconnect or reposition the wiring harness(es) around the head as necessary.
  8.  
  9. Remove the distributor.
  10.  
  11. Remove the exhaust manifold and its gaskets.
  12.  
  13. Remove the fuel delivery pipe and the injectors. DO NOT drop the injectors.
  14.  
  15. Remove the intake manifold support bracket; remove the intake manifold and the intake air control valve.
  16.  
  17. Remove the power steering drive belt.
  18.  
  19. Remove the upper timing belt cover and the valve covers.
  20.  
  21. Remove the water outlet fitting with the bypass pipe and the belt adjusting bar.
  22.  
  23. Remove the spark plugs.
  24.  
  25. Turn the crankshaft clockwise, stopping so that the groove in the crank pulley aligns with the idler pulley bolt. Additionally, check that the valve lifters on No. 1 cylinder are loose (the cam lobes are NOT depressing the lifters). If the valves are under tension, rotate the crank 1 full revolution and check again. The engine is now on TDC/compression.
  26.  
  27. Remove the right motor mount.
  28.  
  29. Remove the water pump pulley.
  30.  
  31. Remove the lower and middle (Nos. 2 and 3) timing belt covers.
  32.  


WARNING
The bolts are different lengths. Label or diagram the correct location of each bolt as it is removed. Improper placement during reassembly can cause engine damage.

  1. Place matchmarks on the timing belt and the belt pulleys. Make sure that you mark each pulley and the belt clearly. Additionally, mark an arrow on the belt showing the direction of rotation.
  2.  



Click image to see an enlarged view

Fig. Fig. 7: Examples of matchmarks on timing belt and pulleys. Don't forget an arrow showing the direction of rotation. The belt will break if put on backwards

  1. Carefully slide the timing belt off the camshaft pulleys. Do not pry on the belt with tools. Keep the belt under light upward tension so that the bottom (crankshaft) end doesn't shift position on its pulley.
  2.  
  3. Remove the camshaft pulleys. Use an adjustable wrench to counterhold the cams during removal. Look for the flats on the cam and fit the wrench to them.
  4.  
  5. With the pulleys removed, the end plate (otherwise called No. 4 timing cover) may be removed.
  6.  
  7. Loosen the head bolts in the order shown in the diagram. Make 3 complete passes, loosening them slowly, evenly and in order.
  8.  



Click image to see an enlarged view

Fig. Fig. 8: Remove the head bolts in this sequence - 1988 VIN Code 5 engine

  1. Remove the cylinder head. If it is difficult to remove, it may be pried up gently with a suitable tool. Be very careful not to scratch or gouge the mating surfaces when prying the head up.
  2.  
  3. Keeping the head upright, place it on wooden blocks on the workbench. If the head is to receive further work, the various components will need to be removed. If the head is not to be worked on, the mating surface must be cleaned of all gasket and sealant material before reinstallation.
  4.  
  5. Clean the engine block mating surface of all gasket and sealant material. Use plastic or wooden scrapers so as not gouge the metal. Remove all traces of liquids from the surface and clean out the bolt holes.
  6.  

To install:
  1. Install the new head gasket on the block. Make sure it is properly placed and that all the holes and passages in the block line up with the holes in the gasket.
  2.  
  3. Place the head in position and make sure it is properly seated and aligned.
  4.  
  5. Apply a light coat of oil to the threads of the cylinder head bolts.
  6.  
  7. Install the 10 cylinder head bolts.
  8.  

The bolts for the exhaust side are 108mm long; the bolts for the intake side are 87.5mm long.

  1. Tighten the cylinder head bolts in 3 passes and in sequence. The first pass should tighten them to 8-10 ft. lbs., the second pass to 16. ft. lbs. and the third pass to 22 ft. lbs.
  2.  



Click image to see an enlarged view

Fig. Fig. 9: Tighten the head bolts in this sequence - 1988 VIN Code 5 engine



Click image to see an enlarged view

Fig. Fig. 10: Apply a dot of paint to the front of each head bolt. Apply 90 degree of rotation in the correct sequence. After all are set, repeat the pattern, tightening each bolt through an additional 90 degree - 1988 VIN Code 5 engine

  1. Mark the front (towards the front of the car) of each bolt with a dot of paint.
  2.  
  3. In the specified order, tighten each bolt through exactly 90° of rotation.
  4.  
  5. Repeat the procedure, tightening each bolt an additional 90°. Check that the paint marks on each bolt are now facing rearward.
  6.  
  7. Apply RTV sealer or equivalent to the cylinder head. Install new cam end seals and coat them lightly with multi-purpose grease.
  8.  



Click image to see an enlarged view

Fig. Fig. 11: Sealant must be applied to the head before reinstalling the valve cover - 1988 VIN Code 5 engine

  1. Install the end plate or No. 4 timing cover.
  2.  
  3. Install the right side engine mount bracket and tighten its bolts to 18 ft. lbs.
  4.  
  5. Install the camshaft pulleys. Be sure to align the camshaft knock pin and the camshaft pulley. Tighten the pulley bolts to 34 ft. lbs.
  6.  



Click image to see an enlarged view

Fig. Fig. 12: Align the cam pulleys before installing the timing belt - 1988 VIN Code 5 engine

  1. Install the lower and middle (Nos. 2 and 3) timing belt covers. Remember that the bolts are different lengths; make certain the correct bolt is in the correct location.
  2.  
  3. Install the water pump pulley.
  4.  
  5. Install the right engine mount. Tighten the through bolt to 58 ft. lbs.
  6.  
  7. Install the spark plugs. Correct tightness is 13 ft. lbs.
  8.  
  9. Reinstall the water outlet with the bypass pipe and the belt adjusting bar.
  10.  
  11. Install the valve covers.
  12.  
  13. Install the alternator and power steering drive belts. Adjust the belts to the correct tension.
  14.  
  15. Install the intake manifold and intake air control valve. Tighten the bolts to 20 ft. lbs
  16.  
  17. Install the bracket and support for the intake manifold.
  18.  
  19. Install the fuel delivery pipe and the injectors. Make sure the insulators and spacers have been placed properly. Make sure the injectors rotate smoothly in their seats.
  20.  
  21. Tighten the delivery pipe retaining bolts to 13. ft. lbs.
  22.  
  23. Install the exhaust manifold tighten its nuts and bolts to 18 ft. lbs.
  24.  
  25. Reinstall the distributor.
  26.  
  27. Attach, reposition or connect the wiring harness(es) around the head. Make sure that all retaining clips are used and are secure. Double check the wiring to eliminate any contact with moving parts.
  28.  
  29. Install the vacuum pipe and the cylinder head rear cover with a new gasket.
  30.  
  31. Connect the first and second bypass hoses to the auxiliary air valve.
  32.  
  33. Connect the No. 1 fuel line.
  34.  
  35. Use new gaskets and connect the cold start injector line. Tighten the bolts to 13 ft. lbs.
  36.  
  37. Replace the EGR valve and use a new gasket.
  38.  
  39. Use a new O-ring and attach the fuel pressure regulator. Tighten the regulator bolts to 6.8 ft. lbs (82 inch lbs.)
  40.  
  41. Install the PCV hose and the brake vacuum hose.
  42.  
  43. Install the radiator hose at the radiator and the cylinder head.
  44.  
  45. Install the ignition coil.
  46.  
  47. Install the cruise control actuator and bracket assembly if so equipped.
  48.  
  49. Observing the labels made earlier, connect the vacuum hose to the throttle body.
  50.  
  51. Attach the heater hose to the cylinder head rear cover.
  52.  
  53. Connect the throttle valve and accelerator cables.
  54.  
  55. Connect the cruise control cable, if so equipped.
  56.  
  57. Install the air cleaner assembly.
  58.  
  59. Confirm that the draincocks on the radiator and engine block are closed. Fill the cooling system with coolant.
  60.  
  61. Double check all installation items, paying particular attention to loose hoses or hanging wires, untightened nuts, poor routing of hoses and wires (too tight or rubbing) and tools left in the engine area.
  62.  
  63. Connect the negative battery cable.
  64.  
  65. Start the engine. During the warm up period, check for any sign of leakage or overheating. Check engine timing and adjust the idle speed if necessary.
  66.  
  67. After the engine is shut off, check the drive belts and adjust the tension if necessary.
  68.  

1989-90 VIN Code 6 Engine, 1991-92 VIN Code 5 Engine

See Figures 3 and 13 through 16

All wires and hoses should be labeled at the time of removal. The amount of time saved during reassembly makes the extra effort well worthwhile.

  1. Disconnect the negative battery cable.
  2.  
  3. Open the draincocks on the engine and radiator. Collect the coolant in clean containers.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Raise the vehicle and safely support it on jackstands.
  2.  
  3. Remove the lower right splash (stone) shield.
  4.  
  5. Remove the 2 covers for the rear engine mount nuts and studs.
  6.  
  7. Remove the 2 rear transaxle mount-to-main crossmember mounting nuts.
  8.  
  9. Remove the 2 center mount-to-center crossmember nuts.
  10.  
  11. Lower the vehicle to the ground.
  12.  
  13. Remove the air cleaner assembly.
  14.  
  15. Disconnect or remove throttle cable, the transmission kick-down cable (automatic) and, if equipped, the cruise control actuator cable.
  16.  
  17. Label and disconnect the vacuum lines. Loosen, disconnect or reposition the wiring harnesses running to the head.
  18.  
  19. Disconnect the fuel inlet line.
  20.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the cold start injector line.
  2.  
  3. Remove the coolant hoses by disconnecting their junctions at the head.
  4.  
  5. Disconnect the heater hoses.
  6.  
  7. Remove the water outlet housing and the water inlet housing.
  8.  
  9. Label and remove the spark plug wires.
  10.  
  11. Remove the PCV valve.
  12.  
  13. Loosen the air conditioning compressor, power steering pump and alternator brackets as necessary; remove the valve cover.
  14.  
  15. Remove the drive belts.
  16.  
  17. Remove the air conditioning idler pulley.
  18.  
  19. Disconnect the wiring at the cruise control actuator (if so equipped); remove the actuator and its bracket.
  20.  
  21. Remove the windshield washer reservoir.
  22.  
  23. Support the engine with a support fixture such as GM J 28467-A or a chain hoist. Alternatively, a floor jack may be placed below the engine; use a piece of wood on the jack to distribute the load.
  24.  
  25. Remove the right engine mount through bolt.
  26.  
  27. Raise the engine enough to gain access to the water pump pulley bolts.
  28.  
  29. Remove the water pump pulley.
  30.  
  31. Lower the engine back to its normal position. Remove the wiring harness from the upper timing belt cover.
  32.  
  33. Raise the vehicle and safely support it on jackstands.
  34.  
  35. Remove the cylinder head-to-cylinder block bracket.
  36.  
  37. Remove the exhaust pipe support bracket and disconnect the exhaust pipe from the exhaust manifold.
  38.  
  39. Remove the upper timing belt cover and then the center timing belt cover.
  40.  

The timing belt is exposed with the cover removed. Do not allow the belt to become contaminated with fluids or lubricants. This includes accidental contact by rags, fingerprints, etc.

  1. Remove the right engine mount bracket.
  2.  
  3. By turning the crankshaft clockwise, set the engine to TDC/compression. Align the timing mark at zero (on the crank) and check that the valve lifters for No. 1 cylinder are NOT under compression from the camshafts; the cam lobes should be pointed up. The small hole in the exhaust camshaft pulley should be aligned with the mark on the camshaft cap.
  4.  
  5. Remove the distributor.
  6.  
  7. Remove the plug from the lower timing belt cover.
  8.  
  9. Matchmark the timing belt and pulleys at the crankshaft and both camshafts. Mark an arrow on the belt showing the direction of rotation.
  10.  
  11. Loosen the idler pulley bolt and push the pulley into its loosest position. Tighten the bolt to hold the idler in this loosened position.
  12.  



Click image to see an enlarged view

Fig. Fig. 13: Loosen the idler pulley and move it to its loosest position - 1989-90 VIN Code 6 and 1991-92 VIN Code 5 engines

  1. Holding the timing belt with a clean cloth, slide the belt off the camshaft pulleys. Keep light upward tension on the belt so that it does not change its position on the lower (crankshaft) pulley.
  2.  


WARNING
Do not pry on the belt with tools. Do not crease or crimp the belt. Be careful not to drop anything into the lower belt cover. Keep the timing belt clean and free of fluids and lubricants.

  1. Using a 10mm, 12-point deep socket wrench, loosen the cylinder head bolts in the proper sequence. It is recommended that the tension be released in 2 or even 3 passes.
  2.  


WARNING
Head warping or cracking can result from improper removal procedures.



Click image to see an enlarged view

Fig. Fig. 14: Remove the cylinder head bolts in this order - 1989-90 VIN Code 6 and 1991-92 VIN Code 5 engines

  1. Remove the cylinder head with the manifolds attached. If the head is difficult to lift off, carefully pry with a suitable tool between the head and a projection on the block. Be careful not to scratch or gouge the mating surfaces of the head or block.
  2.  
  3. Place the head on wooden blocks on the workbench. If the head is to be disassembled, the external parts will need to be removed. If the head is to be reused intact, the mating surface must be cleaned of all gasket and sealant material. Clean the mating surface on the block of all traces of gasket material and fluids. Clean the bolt holes, removing all fluid and solid material.
  4.  

To install:
  1. When reassembling, place the new head gasket in position on the block. Make sure it is placed correctly and that all the holes line up.
  2.  
  3. Carefully install the cylinder head in position on the block. Make sure the head is seated over the guide dowels.
  4.  
  5. Apply a light coat of engine oil to the threads of the head bolts and under the caps of the bolts. Place the bolts in their holes.
  6.  
  7. Tighten the bolts in the proper sequence. Repeat the pattern 3 times, tightening the first pass to 14 ft. lbs., the second pass to 28 ft. lbs. and the third pass to the final setting of 44 ft. lbs.
  8.  



Click image to see an enlarged view

Fig. Fig. 15: Install the cylinder head bolts in this order - 1989-90 VIN Code 6 and 1991-92 VIN Code 5 engines

  1. If the camshafts have not been turned while the head was removed, double check their placement against the marks on the head. If the cams were moved, they must be turned into the TDC/compression position.
  2.  
  3. Double check that the crankshaft is still in its TDC position. Carefully reinstall the timing belt over the cam pulleys, making sure the matchmarks align exactly. The slightest error in placement can greatly reduce engine performance and possibly damage the engine.With the belt correctly installed, loosen the bolt holding the idler pulley in the loosened position. The pulley will spring against the belt, providing tension on it. Turn the crankshaft pulley clockwise 2 full revolutions (from TDC to TDC) and double check that all the components are properly aligned. Tighten the idler pulley bolt to 27 ft. lbs.
  4.  
  5. Reinstall the distributor.
  6.  
  7. Attach the right side engine mount bracket.
  8.  
  9. Install the air conditioning idler pulley.
  10.  
  11. Install the center timing belt cover and the upper timing belt cover.
  12.  
  13. Raise the vehicle and safely support it on jackstands.
  14.  
  15. Using new gaskets and bolts, connect the exhaust pipe to the exhaust manifold. Tighten the bolts to 18 ft. lbs. Install the exhaust manifold support bracket.
  16.  
  17. Install the cylinder head-to-cylinder block bracket.
  18.  
  19. Lower the vehicle to the ground. Connect or reinstall the wiring harness to the upper timing belt cover.
  20.  
  21. Raise the engine enough to gain access to the water pump. Install the water pump pulley and lower the engine into its normal position.
  22.  
  23. Install the right engine mount through bolt and tighten it to 64 ft. lbs. When this bolt is secured, the engine lifting apparatus may be removed from the car.
  24.  
  25. Install the windshield washer reservoir.
  26.  
  27. If equipped with cruise control, reinstall the actuator and its bracket and connect the wiring to the actuator.
  28.  
  29. Install the drive belts and adjust them to the proper tension.
  30.  
  31. Place sealant on the valve cover in the proper locations and install the valve cover. Tighten the retaining nuts to 15 ft. lbs.
  32.  



Click image to see an enlarged view

Fig. Fig. 16: Apply sealant to these points before reinstalling the valve cover - 1989-90 VIN Code 6 and 1991-92 VIN Code 5 engines

  1. Install the PCV valve.
  2.  
  3. Install the spark plugs, and connect the water inlet housing and the water outlet housing.
  4.  
  5. Reinstall the heater hoses and the coolant hoses.
  6.  
  7. Install the fuel rail and injectors.
  8.  
  9. Connect the cold start injector pipe.
  10.  
  11. Connect the fuel inlet line.
  12.  
  13. Observing the labels made earlier, carefully connect the vacuum lines and electrical leads. Make sure the vacuum hoses are properly seated on their ports and are not kinked or twisted. Electrical connectors must be clean and firmly attached at all points. Double check the routing of lines and wires to avoid any contact with moving parts.
  14.  
  15. Depending on equipment, connect the transaxle kick-down cable (automatic), the cruise control actuator cable and/or the accelerator cable.
  16.  
  17. Install the air cleaner assembly.
  18.  
  19. Raise the vehicle and safely support it on jackstands. Attach the 2 rear mount-to-main crossmember nuts and tighten them to 45 ft. lbs. Install the 2 center mount-to-center crossmember nuts and tighten them to 45 ft. lbs. Install the covers on the nuts and studs.
  20.  
  21. Install the lower right splash shield.
  22.  
  23. Lower the vehicle to the ground.
  24.  
  25. Confirm that the radiator and engine block draincocks are closed and refill the cooling system.
  26.  
  27. Double check all installation items, paying particular attention to loose hoses or hanging wires, untightened nuts, poor routing of hoses and wires (too tight or rubbing) and tools left in the engine area.
  28.  
  29. Connect the negative battery cable.
  30.  
  31. Start the engine. During the warm up period, check for any sign of leakage or overheating. Check engine timing and adjust the idle speed if necessary.
  32.  
  33. After the engine is shut off, check the drive belts and adjust the tension if necessary.
  34.  

1990 VIN Code 5 Engine 1991-92 VIN Code 6 Engine

See Figures 2, 17 and 18

  1. Disconnect the negative battery cable
  2.  
  3. Open the drain cocks on the engine and radiator. Collect the coolant in clean containers.
  4.  
  5. Remove the air cleaner assembly.
  6.  
  7. Disconnect the cruise control cable if so equipped.
  8.  
  9. Disconnect the throttle cable from the throttle linkage.
  10.  
  11. Remove the heater hose from the cylinder head rear cover.
  12.  
  13. Label and remove the vacuum hoses from the throttle body.
  14.  
  15. If equipped with cruise control, remove the actuator and bracket assembly.
  16.  
  17. Remove the ignition coil.
  18.  
  19. Remove the upper radiator hose from the cylinder head and the radiator.
  20.  
  21. Remove the brake booster vacuum hose.
  22.  
  23. Remove the PCV hose.
  24.  
  25. Unbolt and remove as a unit the fuel pressure regulator.
  26.  
  27. Unbolt and remove the EGR valve with the lines attached.
  28.  
  29. Remove the cold start injector hose.
  30.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the No. 1 fuel line.
  2.  
  3. Remove the first and second water bypass hoses from the auxiliary air valve.
  4.  
  5. Remove the vacuum pipe and the cylinder head rear cover.
  6.  
  7. Remove, disconnect or reposition the wiring harness(es) around the head as necessary.
  8.  
  9. Remove the distributor.
  10.  
  11. Remove the exhaust manifold and its gaskets.
  12.  
  13. Remove the fuel delivery pipe and the injectors. Do not drop the injectors.
  14.  
  15. Remove the intake manifold support bracket; remove the intake manifold and the intake air control valve.
  16.  
  17. Remove the power steering drive belt.
  18.  
  19. Remove the upper timing belt cover and the valve covers.
  20.  
  21. Remove the water outlet fitting with the bypass pipe and the belt adjusting bar.
  22.  
  23. Remove the spark plugs.
  24.  
  25. Turn the crankshaft clockwise, stopping so that the groove in the crank pulley aligns with the idler pulley bolt. Additionally, check that the valve lifters on No. 1 cylinder are loose (the cam lobes are not depressing the lifters). If the valves are under tension, rotate the crank 1 full revolution and check again. The engine is now on TDC/compression.
  26.  
  27. Remove the right motor mount.
  28.  
  29. Remove the water pump pulley.
  30.  
  31. Remove the lower and middle (Nos. 2 and 3) timing belt covers.
  32.  

The bolts are different lengths. Label or diagram the correct location of each bolt as it is removed. Improper placement during reassembly can cause engine damage.

  1. Place matchmarks on the timing belt and the belt pulleys. Make sure to mark each pulley and the belt clearly. Additionally, mark an arrow on the belt showing the direction of rotation.
  2.  
  3. Carefully slide the timing belt off the camshaft pulleys. Do not pry on the belt with tools. Keep the belt under light upward tension so that the bottom (crankshaft) end doesn't shift position on its pulley.
  4.  
  5. Remove the camshaft pulleys. Use an adjustable wrench to counter hold the cams during removal. Look for the flats on the cam and fit the wrench to them.
  6.  
  7. With the pulleys removed, the end plate (otherwise called No. 4 timing cover) may be removed.
  8.  
  9. Loosen the head bolts in the proper sequence. Make 3 complete passes, loosening them slowly, evenly and in order.
  10.  



Click image to see an enlarged view

Fig. Fig. 17: Cylinder head bolt loosening sequence - 1990 VIN Code 5 and 1991-92 VIN Code 6 engine

  1. Remove the cylinder head. If it is difficult to remove, it may be pried up gently with a suitable tool. Be very careful not to scratch or gouge the mating surfaces when prying the head up.
  2.  
  3. Keeping the head upright, place it on wooden blocks on the workbench. If the head is to receive further work, the various components will need to be removed. If the head is not to be worked on, the mating surface must be cleaned of all gasket and sealant material before reinstallation.
  4.  
  5. Clean the engine block mating surface of all gasket and sealant material. Use plastic or wooden scrapers so as not gouge the metal. Remove all traces of liquids from the surface and clean out the bolt holes.
  6.  

To install:
  1. Install the new head gasket on the block. Make sure it is properly placed and that all the holes and passages in the block line up with the holes in the gasket.
  2.  
  3. Place the head in position and make sure it is properly seated and aligned.
  4.  
  5. Apply a light coat of oil to the threads of the cylinder head bolts.
  6.  
  7. Install the 10 cylinder head bolts.
  8.  

The bolts for the exhaust side are 108mm long; the bolts for the intake side are 87.5mm long.

  1. Tighten the cylinder head bolts in 3 passes and in sequence. The first pass should tighten them to 8-10 ft. lbs. (11-14 Nm), the second pass to 16 ft. lbs. (22 Nm) and the third pass to 44 ft. lbs. (60 Nm).
  2.  



Click image to see an enlarged view

Fig. Fig. 18: Cylinder head bolt tightening sequence - 1990 VIN Code 5 and 1991-92 VIN Code 6 engine

  1. Apply RTV sealer or equivalent to the cylinder head. Install new camshaft end seals and coat them lightly with multi-purpose grease.
  2.  
  3. Install the end plate or No. 4 timing cover.
  4.  
  5. Install the right side engine mount bracket and tighten its bolts to 64 ft. lbs. (87 Nm).
  6.  
  7. Install the camshaft pulleys. Be sure to align the camshaft knock pin and the camshaft pulley. Tighten the pulley bolts to 34 ft. lbs. (47 Nm).
  8.  
  9. Install the lower and middle (No. 2 and 3) timing belt covers. Remember that the bolts are different lengths; make certain the correct bolt is in the correct location.
  10.  
  11. Install the water pump pulley.
  12.  
  13. Install the right engine mount. Tighten the through bolt to 64 ft. lbs. (87 Nm).
  14.  
  15. Install the spark plugs. Correct tightness is 13 ft. lbs. (18 Nm).
  16.  
  17. Reinstall the water outlet with the bypass pipe and the belt adjusting bar.
  18.  
  19. Install the valve covers.
  20.  
  21. Install the alternator and power steering drive belts. Adjust the belts to the correct tension.
  22.  
  23. Install the intake manifold and intake air control valve. Tighten the bolts to 20 ft. lbs. (27 Nm).
  24.  
  25. Install the bracket and support for the intake manifold.
  26.  
  27. Install the fuel delivery pipe and the injectors. Make sure the insulators and spacers have been placed properly. Make sure the injectors rotate smoothly in their seats.
  28.  
  29. Tighten the delivery pipe retaining bolts to 13 ft. lbs. (18 Nm).
  30.  
  31. Install the exhaust manifold tighten its nuts and bolts to 18 ft. lbs. (25 Nm).
  32.  
  33. Reinstall the distributor.
  34.  
  35. Attach, reposition or connect the wiring harness(es) around the head. Make sure that all retaining clips are used and are secure. Double check the wiring to eliminate any contact with moving parts.
  36.  
  37. Install the vacuum pipe and the cylinder head rear cover with a new gasket.
  38.  
  39. Connect the first and second bypass hoses to the auxiliary air valve.
  40.  
  41. Connect the No. 1 fuel line.
  42.  
  43. Use new gaskets and connect the cold start injector line. Tighten the bolts to 13 ft. lbs. (18 Nm).
  44.  
  45. Replace the EGR valve and use a new gasket.
  46.  
  47. Use a new O-ring and attach the fuel pressure regulator. Tighten the regulator bolts to 6.8 ft. lbs (82 in. lbs.)
  48.  
  49. Install the PCV hose and the brake vacuum hose.
  50.  
  51. Install the radiator hose at the radiator and the cylinder head.
  52.  
  53. Install the ignition coil.
  54.  
  55. Install the cruise control actuator and bracket assembly if so equipped.
  56.  
  57. Observing the labels made earlier, connect the vacuum hose to the throttle body.
  58.  
  59. Attach the heater hose to the cylinder head rear cover.
  60.  
  61. Connect the throttle valve and accelerator cables.
  62.  
  63. Connect the cruise control cable, if so equipped.
  64.  
  65. Install the air cleaner assembly.
  66.  
  67. Confirm that the drain cocks on the radiator and engine block are closed. Fill the cooling system with coolant.
  68.  
  69. Double check all installation items, paying particular attention to loose hoses or hanging wires, loosened nuts, poor routing of hoses and wires (too tight or rubbing) and tools left in the engine area.
  70.  
  71. Connect the negative battery cable.
  72.  
  73. Start the engine. During the warm up period, check for any sign of leakage or overheating. Check engine timing and adjust the idle speed if necessary.
  74.  
  75. After the engine is shut off, check the drive belts and adjust the tension if necessary.
  76.  

1993

See Figures 19 and 20

  1. Disconnect the negative battery cable and relieve the fuel system pressure.
  2.  
  3. Remove the timing belt and tensioner as outlined in this section.
  4.  
  5. Remove the camshafts as outlined in this section.
  6.  
  7. Disconnect and label the hoses from the intake chamber.
  8.  
  9. Disconnect the A/C actuator electrical connector, if so equipped.
  10.  
  11. Disconnect the hoses and the electrical connector and remove the EGR SV valve.
  12.  
  13. Remove the engine wire clamp.
  14.  
  15. Remove the 3 bolts and the intake manifold brace.
  16.  
  17. Disconnect the hose clamp and fuel return hose from the pressure regulator.
  18.  
  19. Remove the 1 bolt and nut and the air pipe from the intake manifold.
  20.  
  21. On California vehicles, remove the EGR valve and vacuum modulator.
  22.  
  23. Remove the throttle body from the manifold.
  24.  
  25. Remove the fuel inlet hose clamp bolt and the air intake chamber brace with gasket.
  26.  
  27. Disconnect the 2 PCV hoses from the cylinder head cover.
  28.  
  29. Disconnect the vacuum hose from the pressure regulator.
  30.  
  31. Remove the 3 bolts and 2 nuts and the air intake chamber cover with gasket.
  32.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Remove the union bolt, 2 gaskets and disconnect the fuel inlet pipe from the fuel rail.
  2.  
  3. Disconnect the injector electrical connectors.
  4.  
  5. Remove the 2 bolts and the fuel rail with the 4 injectors attached.
  6.  
  7. Remove the 4 insulators and 2 spacers from the cylinder head.
  8.  
  9. Remove the 7 bolts, ground strap, 2 nuts and the intake manifold with the gasket from the cylinder head.
  10.  
  11. Disconnect the oxygen sensor electrical connector.
  12.  
  13. Remove the 2 exhaust pipe to exhaust manifold bolts and 2 front pipe to exhaust manifold nuts (front pipe to warm up 3 way catalytic converter WU TWC on Calif. spec. vehicles).
  14.  
  15. Remove the 5 bolts and the upper heat insulator.
  16.  
  17. Remove the 3 bolts and the exhaust manifold brace (2 bolts on Calif. spec. vehicles).
  18.  
  19. Remove the 5 nuts, exhaust manifold (WU TWC on Calif. spec. vehicles) and gasket from the cylinder head.
  20.  
  21. Remove the cylinder head bolts in sequence using a 10mm, 12 point deep well socket.
  22.  
  23. Keeping the head upright, place it on wooden blocks on the workbench. If the head is to receive further work, the various components will need to be removed. If the head is not to be worked on, the mating surface must be cleaned of all gasket and sealant material before reinstallation.
  24.  
  25. Clean the engine block mating surface of all gasket and sealant material. Use plastic or wooden scrapers so as not gouge the metal. Remove all traces of liquids from the surface and clean out the bolt holes.
  26.  

To install:
  1. Install the new head gasket on the block. Make sure it is properly placed and that all the holes and passages in the block line up with the holes in the gasket.
  2.  
  3. Place the head in position and make sure it is properly seated and aligned.
  4.  
  5. Apply a light coat of oil to the threads of the cylinder head bolts.
  6.  
  7. Install the 10 cylinder head bolts.
  8.  

The bolts for the exhaust side are 108mm long; the bolts for the intake side are 90mm long.

  1. Tighten the cylinder head bolts in several passes and in sequence to 22 ft. lbs. (29 Nm). Tighten the cylinder head bolts in sequence another 90 degrees. Then tighten the cylinder head bolts an additional 90 degrees.
  2.  

If the correct tightening sequence is not followed, warpage or leakage may result.

  1. Install a new gasket and the exhaust manifold (WU TWC on Calif. spec. vehicles) to the cylinder head and tighten the 5 nuts to 25 ft. lbs. (34 Nm).
  2.  
  3. Install the intake manifold with a new gasket to the cylinder head and secure with the 2 nuts, 7 bolts and ground strap. Tighten the bolts and nuts to 14 ft. lbs. (19 Nm).
  4.  
  5. Install 4 new insulators and 2 spacers to the cylinder head.
  6.  
  7. Install the fuel rail with injectors to the intake manifold and secure with the 2 bolts, but do not fully tighten. Make sure the injectors rotate smoothly, if not replace the O-rings. Make sure the electrical connector is pointed upward. Tighten the fuel rail bolts to 11 ft. lbs. (15 Nm).
  8.  
  9. Install the injector electrical connectors.
  10.  
  11. Install the union bolt, 2 new gaskets and connect the fuel inlet pipe to the fuel rail. Tighten the bolt to 22 ft. lbs. (29 Nm)
  12.  
  13. Install the 3 bolts and 2 nuts and the air intake chamber cover with a new gasket. Tighten to 14 ft. lbs. (19 Nm).
  14.  
  15. Connect the vacuum hose to the pressure regulator.
  16.  
  17. Connect the 2 PCV hoses to the cylinder head cover.
  18.  
  19. Install the air intake chamber brace with a new gasket and tighten the bolt to 21 ft. lbs. (28 Nm).
  20.  
  21. Install the fuel inlet hose clamp bolt and tighten to 89 inch lbs. (10 Nm).
  22.  
  23. Install the throttle body to the manifold using a new gasket and tighten the nuts and bolts to 17 ft. lbs. (23 Nm).
  24.  
  25. Attach the accelerator to the throttle body and tighten the 2 bolts to 11 ft. lbs. (15 Nm).
  26.  
  27. Connect the TP sensor electrical connector.
  28.  
  29. On California vehicles, using new gaskets, install the EGR valve and vacuum modulator. Tighten the EGR to manifold bolts and nuts to 115 inch lbs (13 Nm) and the EGR valve to EGR pipe bolts to 43 ft. Lbs. (59 Nm).
  30.  
  31. On California vehicles, install the 2 vacuum hoses to the throttle body.
  32.  
  33. Install the air pipe to the manifold and tighten the bolt to 80 inch lbs. (9 Nm).
  34.  
  35. Connect the hose clamp and fuel return hose to the pressure regulator.
  36.  
  37. Install the 3 bolts and the intake manifold brace and tighten to 14 ft. lbs. (9 Nm).
  38.  
  39. Install the engine wire clamps.
  40.  
  41. Install the EGR SV valve and connect the hoses and the electrical connector. Tighten the EGR SV valve retaining bolts 115 inch lbs. (13 Nm).
  42.  
  43. Connect the A/C actuator electrical connector, if so equipped.
  44.  
  45. Connect the hoses to the intake chamber.
  46.  
  47. Install the camshafts as outlined in this section.
  48.  
  49. Install the timing belt and tensioner as outlined in this section.
  50.  
  51. Connect the negative battery cable.
  52.  



Click image to see an enlarged view

Fig. Fig. 19: Cylinder head bolt loosening sequence - 1993 VIN Code 6 & 8 engines



Click image to see an enlarged view

Fig. Fig. 20: Cylinder head bolt tightening sequence - 1993 VIN Code 6 & 8 engines

CYLINDER HEAD CLEANING AND INSPECTION



1985-88 VIN Code 4 Engine

See Figures 21 through 25

  1. With the head removed from the car, remove the carburetor, the fuel pump and the intake and exhaust manifolds.
  2.  
  3. Remove the rocker arm assembly, following procedures outlined earlier in this section.
  4.  
  5. Use a dial indicator to measure the camshaft end-play (axial end-play or throughst clearance). Standard play is 0.08-0.18mm. Maximum allowable free play is 0.25mm. Free-play at or beyond the maximum requires replacement of the head.
  6.  



Click image to see an enlarged view

Fig. Fig. 21: Use of a dial indicator and check the camshaft end-play. - 1985-88 VIN Code 4 engine

  1. Remove the camshaft, following procedures outlined later in this section.
  2.  
  3. Remove the valves, following procedures outlined later in this section.
  4.  
  5. Using a wire brush chucked into an electric drill, remove all the carbon from the combustion chambers in the head. Be careful not to scratch the head surface.
  6.  



Click image to see an enlarged view

Fig. Fig. 22: Removing combustion chamber carbon; make sure it is removed and not merely burnished

  1. Use a gasket scraper and remove all material from the manifold and head surfaces, again being careful not to scratch the surface.
  2.  



Click image to see an enlarged view

Fig. Fig. 23: Do not scratch the head mating surface when removing old gasket material

  1. Use a valve guide brush or a fine-bristled rifle bore brush with solvent to clean the valve guides.
  2.  
  3. Use a clean cloth and a stiff bristle brush with solvent to thoroughly clean the head assembly. Make sure that no material is washed into the bolt holes or passages. If possible, dry the head with compressed air to remove fluid and solid matter from all the passages.
  4.  


WARNING
Do not clean the head in a hot tank or chemical bath. Parts of the head will dissolve.

  1. With the head clean and dry, use a precision straight-edge and a feeler gauge to measure the head for warpage. Also measure the manifold faces. Any warpage in excess of the maximum requires replacement of the head.
  2.  



Click image to see an enlarged view

Fig. Fig. 24: Checking the cylinder head for warpage



Click image to see an enlarged view

Fig. Fig. 25: Cylinder head warpage clearances

  1. If all is well with the head to this point, it is highly recommended that it be taken to a professional facility such as a machine shop for sophisticated crack testing. The various procedures are much more reliable than simple examination by eye. The cost is reasonable and the peace of mind is well worth the cost. If any cracks are found, the head must be replaced.
  2.  
  3. While the head is being checked, carefully scrape the carbon from the tops of the pistons. Don't scratch the metal of the piston tops and don't damage the cylinder walls. Remove all the carbon and fluid from the cylinder.
  4.  
  5. If repairs are needed to the valves, camshaft or other components, follow the appropriate procedures outlined in this section.
  6.  

1988 VIN Code 5 Engine

See Figures 22 through 26

  1. With the head removed from the car, remove the camshafts following procedures outlined later in this section.
  2.  
  3. Remove the valve lifters and the adjusting shims following procedures outlined later in this section.
  4.  
  5. Remove any external fittings, brackets, cables, etc.
  6.  
  7. Remove the valves following procedures outlined later in this section.
  8.  
  9. Carefully scrape the carbon from the tops of the pistons. Don't scratch the metal of the piston tops and don't damage the cylinder walls. Remove all the carbon and fluid from the cylinder.
  10.  



Click image to see an enlarged view

Fig. Fig. 26: Removing carbon from the piston tops; do not scratch the pistons

  1. Clean all the gasket material from the block, manifold and head surfaces. If possible, use compressed air to blow the carbon and oil from the bolt holes and passages.
  2.  
  3. Using a wire brush chucked into an electric drill, remove all the carbon from the combustion chambers in the head. Be careful not to scratch the head surface.
  4.  
  5. Use a valve guide brush or a fine-bristled rifle bore brush with solvent to clean the valve guides.
  6.  
  7. Use a clean cloth and a stiff bristle brush with solvent to thoroughly clean the head assembly. Make sure that no material is washed into the bolt holes or passages. If possible, dry the head with compressed air to remove fluid and solid matter from all the passages.
  8.  


WARNING
Do not clean the head in a hot tank or chemical bath. Parts of the head will dissolve.

  1. With the head clean and dry, use a precision straight-edge and a feeler gauge to measure the head for warpage. Also measure the manifold faces. Any warpage in excess of the maximum requires replacement of the head.
  2.  

Maximum allowable warpage:


Cylinder block face: 0.05mm
 
Intake manifold face: 0.05mm
 
Exhaust manifold face: 0.10mm
 

  1. If all is well with the head to this point, it is highly recommended that it be taken to a professional facility such as a machine shop for sophisticated crack testing. The various procedures are much more reliable than simple examination by eye. The cost is reasonable and the peace of mind is well worth the cost. If any cracks are found, the head must be replaced.
  2.  

1989-90 VIN Code 6 Engine 1991-92 VIN Code 5 Engine 1993 All Engines

See Figures 22, 23, 24, 25 and 27

  1. With the head removed from the engine, remove the intake and exhaust manifolds, following procedures outline earlier in this section.
  2.  
  3. Remove the camshafts, following procedures outlined later in this section.
  4.  
  5. Remove the valve lifters and the adjusting shims.
  6.  
  7. Remove the spark plug tubes.
  8.  
  9. Remove the engine hoist hooks.
  10.  
  11. Remove the valves, using procedures outlined later in this section.
  12.  
  13. On 1989-92 engines, remove the half-circle plug at the end of the head.
  14.  



Click image to see an enlarged view

Fig. Fig. 27: Remove the half circle plug from the cylinder head

  1. Using a wire brush chucked into an electric drill, remove all the carbon from the combustion chambers in the head. Be careful not to scratch the head surface.
  2.  
  3. Use a valve guide brush or a fine-bristled rifle bore brush with solvent to clean the valve guides.
  4.  
  5. Use a clean cloth and a stiff bristle brush with solvent to thoroughly clean the head assembly. Make sure that no material is washed into the bolt holes or passages. If possible, dry the head with compressed air to remove fluid and solid matter from all the passages.
  6.  


WARNING
Do not clean the head in a hot tank or chemical bath. Parts of the head will dissolve.

  1. With the head clean and dry, use a precision straight-edge and a feeler gauge to measure the head for warpage. Also measure the manifold faces. Any warpage in excess of the maximum requires replacement of the head.
  2.  

Maximum allowable warpage:


Cylinder block face: 0.05mm
 
Intake manifold face: 0.10mm
 
Exhaust manifold face: 0.10mm
 

  1. If all is well with the head to this point, it is highly recommended that it be taken to a professional facility such as a machine shop for sophisticated crack testing. The various procedures are much more reliable than simple examination by eye. The cost is reasonable and the peace of mind is well worth the cost. If any cracks are found, the head must be replaced.
  2.  

1990 VIN Code 5 Engine 1991-92 VIN Code 6 Engine

See Figures 22, 23, 24 and 25

  1. With the head removed from the engine, remove the intake and exhaust manifolds, following procedures outline earlier in this section.
  2.  
  3. Remove the camshafts, following procedures outlined later in this section.
  4.  
  5. Remove the valve lifters and the adjusting shims.
  6.  
  7. Remove the spark plug tubes.
  8.  
  9. Remove the engine hoist hooks.
  10.  
  11. Remove the valves, using procedures outlined later in this section.
  12.  
  13. Remove the half-circle plug at the end of the head.
  14.  
  15. Using a wire brush chucked into an electric drill, remove all the carbon from the combustion chambers in the head. Be careful not to scratch the head surface.
  16.  
  17. Use a valve guide brush or a fine-bristled rifle bore brush with solvent to clean the valve guides.
  18.  
  19. Use a clean cloth and a stiff bristle brush with solvent to thoroughly clean the head assembly. Make sure that no material is washed into the bolt holes or passages. If possible, dry the head with compressed air to remove fluid and solid matter from all the passages.
  20.  


WARNING
Do not clean the head in a hot tank or chemical bath. Parts of the head will dissolve.

  1. If all is well with the head to this point, it is highly recommended that it be taken to a professional facility such as a machine shop for sophisticated crack testing. The various procedures are much more reliable than simple examination by eye. The cost is reasonable and the peace of mind is well worth the cost. If any cracks are found, the head must be replaced.
  2.  

CYLINDER HEAD RESURFACING



The Nova and Prizm cylinder heads from all engines may be resurfaced by a reputable machine shop. Resurfacing is recommended if the engine suffered a massive overheating, such as from a failed head gasket.

The heads are manufactured to be as light as possible; consequently, there is not much excess metal on the face. Any machining must be minimal. If too much metal is removed, the head becomes unusable. A head which exceeds the maximum warpage specification CANNOT be resurfaced. The machine shop will have a list of minimum head thicknesses; at no time may this minimum be exceeded.

 
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