Jeep Wrangler/YJ 1987-1995 Repair Guide

Cylinder Head

Print

REMOVAL & INSTALLATION



It is important to note that each engine has its own head bolt tightening sequence and torque. Incorrect tightening procedure may cause head warpage and compression loss. Correct sequence and torque for each engine model is shown in this section.

2.5L Engine
1987-88 VEHICLES

See Figures 1 and 2

  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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. Disconnect the hoses at the thermostat housing.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Remove the rocker arm cover. The cover seal is RTV sealer. Break the seal with a clean putty knife or razor blade. Don't attempt to remove the cover until the seal is broken. To remove the cover, pry where indicated at the bolt holes.
  6.  
  7. Remove the rocker arms. Keep them in order!
  8.  
  9. Remove the pushrods. Keep them in order!
  10.  
  11. Remove the power steering pump bracket.
  12.  
  13. Suspend the pump out of the way.
  14.  
  15. Remove the intake and exhaust manifolds.
  16.  
  17. Remove the air conditioning compressor drive belt.
  18.  
  19. Loosen the alternator drive belt.
  20.  
  21. Remove the compressor/alternator bracket mounting bolt.
  22.  
  23. Unbolt the compressor and suspend it out of the way. DO NOT DISCONNECT THE REFRIGERANT LINES!
  24.  
  25. Remove the spark plugs.
  26.  
  27. Disconnect the temperature sending unit wire.
  28.  
  29. Remove the head bolts.
  30.  
  31. Lift the head off the engine and place it on a clean workbench.
  32.  
  33. Remove the head gasket.
  34.  



Click image to see an enlarged view

Fig. Fig. 1: Cylinder head and components-2.5L engine



Click image to see an enlarged view

Fig. Fig. 2: Cylinder head tightening sequence-1987-88 2.5L engine

To install:
  1. Thoroughly clean the gasket mating surfaces. Remove all traces of old gasket material. Remove all carbon deposits from the combustion chambers. Lay a straightedge across the head and check for flatness. Total deviation should not exceed 0.001 in. (0.025mm).
  2.  
  3. Do not apply sealant to the head or block. Coat both sides of the gasket with sealer. The gasket should be stamped TOP for installation. Place the gasket on the block.
  4.  
  5. Install the head on the block.
  6.  
  7. Coat the threads of stud/bolt No. 8 in the torque sequence illustration, with Loctite 592 or equivalent. Install all the bolts. Tighten bolt Nos. 1 through 7 in three equal steps, in the sequence shown, to 85 ft. lbs. (115 Nm). Then, torque the No. 8 stud/bolt to 75 ft. lbs. (102 Nm).
  8.  
  9. Connect the temperature sending unit wire.
  10.  
  11. Install the spark plugs.
  12.  
  13. Install the compressor.
  14.  
  15. Install the compressor/alternator bracket mounting bolt.
  16.  
  17. Adjust the alternator drive belt.
  18.  
  19. Install the air conditioning compressor drive belt.
  20.  
  21. Install the intake and exhaust manifolds.
  22.  
  23. Install the power steering pump bracket.
  24.  
  25. Install the pushrods. Keep them in order!
  26.  
  27. Install the rocker arms. Keep them in order!
  28.  
  29. Thoroughly clean the mating surfaces of the head and rocker cover. Run a 1 / 8 in. (3mm) bead of RTV sealer along the length of the sealing surface of the head. Position the cover on the head within 10 minutes of applying the sealer. Torque the cover bolts, in a crisscross pattern, to 55 inch lbs. (6 Nm).
  30.  
  31. Install the air cleaner.
  32.  
  33. Connect the hoses at the thermostat housing.
  34.  
  35. Connect the battery ground.
  36.  
  37. Fill the cooling system.
  38.  

1989 VEHICLES

See Figures 3, 4, 5 and 6



Click image to see an enlarged view

Fig. Fig. 3: Fabricate alignment dowels-1989-95 2.5L engines



Click image to see an enlarged view

Fig. Fig. 4: Alignment dowel locations-1989-95 2.5L engines



Click image to see an enlarged view

Fig. Fig. 5: Cylinder head bolt tightening sequence-1989-95 2.5L engines

  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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. Disconnect the hoses at the thermostat housing.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Remove the rocker arm cover. The cover seal is RTV sealer. Break the seal with a clean putty knife or razor blade. Don't attempt to remove the cover until the seal is broken. To remove the cover, pry where indicated at the bolt holes.
  6.  
  7. Remove the rocker arms. Keep them in order!
  8.  
  9. Remove the pushrods. Keep them in order!
  10.  
  11. Remove the power steering pump bracket.
  12.  
  13. Suspend the pump out of the way.
  14.  
  15. Remove the intake and exhaust manifolds.
  16.  
  17. Remove the air conditioning compressor drive belt.
  18.  
  19. Loosen the alternator drive belt.
  20.  
  21. Remove the compressor/alternator bracket mounting bolt.
  22.  
  23. Unbolt the compressor and suspend it out of the way. DO NOT DISCONNECT THE REFRIGERANT LINES!
  24.  
  25. Remove the spark plugs.
  26.  
  27. Disconnect the temperature sending unit wire.
  28.  
  29. Remove the head bolts.
  30.  
  31. Lift the head off the engine and place it on a clean workbench.
  32.  
  33. Remove the head gasket.
  34.  

To install:
  1. Thoroughly clean the gasket mating surfaces. Remove all traces of old gasket material. Remove all carbon deposits from the combustion chambers. Lay a straightedge across the head and check for flatness. Total deviation should not exceed 0.001 in. (0.025mm).
  2.  

The cylinder head gasket used on the 2.5L engine is a composition gasket. The gasket is to be installed dry. Do not use gasket sealing compound on the gasket.

  1. Fabricate 2 cylinder head alignment dowels from 2 used cylinder head bolts. Cut the head of the longest bolt off below the hex head. Then, cut a slot in the top of the dowel to allow easier removal with a screwdriver.
  2.  
  3. Install one dowel in bolt hole No. 10 and the other dowel in bolt hole No. 7.
  4.  
  5. Place the cylinder head gasket over the dowels with the numbers facing up.
  6.  
  7. Place the cylinder head over the dowels.
  8.  
  9. Coat the threads of bolt No. 8 only, with Loctite PST sealant or equivalent.
  10.  
  11. Install all head bolts except Nos. 7 and 10.
  12.  
  13. Tighten the bolts in the sequence shown in the illustration to the following:
    1. Tighten bolts 1 through 10 in sequence to 22 ft. lbs. (30 Nm).
    2.  
    3. Tighten bolts 1 through 10 in sequence to 45 ft. lbs. (61 Nm).
    4.  
    5. Recheck bolts 1 through 10 in sequence to verify that they are 45 ft. lbs. (61 Nm).
    6.  
    7. Tighten bolts 1 through 7 in sequence to 110 ft. lbs. (149 Nm).
    8.  
    9. Tighten bolt 8 to 100 ft. lbs. (136 Nm).
    10.  
    11. Tighten bolts 9 and 10 to 110 ft. lbs. (149 Nm).
    12.  

  14.  

During the final tightening sequence, bolt No. 8 will be tightened to a lower torque than the rest of the bolts. Do not overtighten bolt No. 8.

  1. Connect the temperature sending unit wire.
  2.  
  3. Install the spark plugs.
  4.  
  5. Install the compressor.
  6.  
  7. Install the compressor/alternator bracket mounting bolt.
  8.  
  9. Adjust the alternator drive belt.
  10.  
  11. Install the air conditioning compressor drive belt.
  12.  
  13. Install the intake and exhaust manifolds.
  14.  
  15. Install the power steering pump bracket.
  16.  
  17. Install the pushrods. Keep them in order!
  18.  
  19. Install the rocker arms. Keep them in order!
  20.  
  21. Thoroughly clean the mating surfaces of the head and rocker cover and install as outlined earlier in this section.
  22.  
  23. Install the air cleaner.
  24.  
  25. Connect the hoses at the thermostat housing.
  26.  
  27. Connect the battery ground.
  28.  
  29. Fill the cooling system.
  30.  

1990-95 VEHICLES

See Figures 6 through 14

  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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. Disconnect the hoses at the thermostat housing.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Remove the rocker arm cover as outlined earlier in this section.
  6.  
  7. Remove the rocker arms. Keep them in order!
  8.  
  9. Remove the pushrods. Keep them in order!
  10.  
  11. Remove the power steering pump bracket.
  12.  
  13. Suspend the pump out of the way.
  14.  
  15. Remove the intake and exhaust manifolds.
  16.  
  17. Remove the air conditioning compressor drive belt.
  18.  
  19. Loosen the alternator drive belt.
  20.  
  21. Remove the compressor/alternator bracket mounting bolt.
  22.  
  23. Unbolt the compressor and suspend it out of the way. DO NOT DISCONNECT THE REFRIGERANT LINES!
  24.  
  25. Remove the spark plugs.
  26.  
  27. Disconnect the temperature sending unit wire.
  28.  



Click image to see an enlarged view

Fig. Fig. 6: Disconnect the coolant hoses at the thermostat housing



Click image to see an enlarged view

Fig. Fig. 7: Disconnect the coolant hoses at the thermostat housing



Click image to see an enlarged view

Fig. Fig. 8: Remove the cylinder head-to-block bolts



Click image to see an enlarged view

Fig. Fig. 9: Cylinder head bolt removed from the head



Click image to see an enlarged view

Fig. Fig. 10: Removing the cylinder head from the engine block

  1. Remove the head bolts.
  2.  
  3. Lift the head off the engine and place it on a clean workbench.
  4.  
  5. Remove the head gasket.
  6.  

To install:
  1. Thoroughly clean the gasket mating surfaces. Remove all traces of old gasket material. Remove all carbon deposits from the combustion chambers. Lay a straightedge across the head and check for flatness. Total deviation should not exceed 0.001 in. (0.025mm).
  2.  

The cylinder head gasket used on the 2.5L engine is a composition gasket. The gasket is to be installed dry. Do not use gasket sealing compound on the gasket.

  1. Fabricate 2 cylinder head alignment dowels from 2 used cylinder head bolts. Cut the head of the longest bolt off below the hex head. Then cut a slot in the top of the dowel to allow easier removal with a screwdriver.
  2.  
  3. Install one dowel in bolt hole No. 10 and the other dowel in bolt hole No. 8.
  4.  
  5. Place the cylinder head gasket over the dowels with the numbers facing up.
  6.  
  7. Place the cylinder head over the dowels.
  8.  
  9. Coat the threads of bolt No. 7 only, with Loctite PST sealant or equivalent.
  10.  
  11. Install all head bolts except Nos. 8 and 10.
  12.  
  13. Tighten the bolts in the sequence shown in the illustration to the following:
    1. Tighten bolts 1 through 10 in sequence to 22 ft. lbs. (30 Nm).
    2.  
    3. Tighten bolts 1 through 10 in sequence to 45 ft. lbs. (61 Nm).
    4.  
    5. Recheck bolts 1 through 10 in sequence to verify that they are 45 ft. lbs. (61 Nm).
    6.  
    7. Tighten bolts 1 through 6 in sequence to 110 ft. lbs. (149 Nm).
    8.  
    9. Tighten bolt 7 to 100 ft. lbs. (136 Nm).
    10.  
    11. Tighten bolts 8 through 10 to 110 ft. lbs. (149 Nm).
    12.  

  14.  

During the final tightening sequence, bolt No. 7 will be tightened to a lower torque than the rest of the bolts. Do not overtighten bolt No. 7.

  1. Connect the temperature sending unit wire.
  2.  
  3. Install the spark plugs.
  4.  
  5. Install the compressor.
  6.  
  7. Install the compressor/alternator bracket mounting bolt.
  8.  
  9. Adjust the alternator drive belt.
  10.  
  11. Install the air conditioning compressor drive belt.
  12.  
  13. Install the intake and exhaust manifolds.
  14.  
  15. Install the power steering pump bracket.
  16.  
  17. Install the pushrods. Keep them in order!
  18.  
  19. Install the rocker arms. Keep them in order!
  20.  
  21. Thoroughly clean the mating surfaces of the head and rocker cover and install as outlined earlier in this section.
  22.  
  23. Install the air cleaner.
  24.  
  25. Connect the hoses at the thermostat housing.
  26.  
  27. Connect the battery ground.
  28.  
  29. Fill the cooling system.
  30.  

4.0L Engine

See Figures 11 and 12



Click image to see an enlarged view

Fig. Fig. 11: Cylinder head bolt No. 14 location-4.0L engine



Click image to see an enlarged view

Fig. Fig. 12: Cylinder head bolt tightening sequence-4.0L and 4.2L engines

  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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. Disconnect the hoses at the thermostat housing.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Remove the rocker arm cover as outlined earlier in this section.
  6.  
  7. Remove the rocker arms. Keep them in order!
  8.  
  9. Remove the pushrods. Keep them in order!
  10.  
  11. Remove the power steering pump bracket.
  12.  
  13. Suspend the pump out of the way.
  14.  
  15. Remove the intake and exhaust manifolds.
  16.  
  17. Remove the air conditioning compressor drive belt.
  18.  
  19. Loosen the alternator drive belt.
  20.  
  21. Remove the compressor/alternator bracket mounting bolt.
  22.  
  23. Unbolt the compressor and suspend it out of the way. DO NOT DISCONNECT THE REFRIGERANT LINES!
  24.  
  25. Remove the spark plugs.
  26.  
  27. Disconnect the temperature sending unit wire.
  28.  
  29. Remove the head bolts.
  30.  

Bolt No. 14 cannot be removed until the head is moved forward.

  1. Pull bolt No. 14 out as far as it will go, then suspend the bolt in this position (tape around the bolt).
  2.  
  3. Lift the head off the engine and place it on a clean workbench.
  4.  
  5. Remove the head gasket.
  6.  

To install:
  1. Thoroughly clean the gasket mating surfaces. Remove all traces of old gasket material. Remove all carbon deposits from the combustion chambers. Lay a straightedge across the head and check for flatness. Total deviation should not exceed 0.001 in. (0.025mm).
  2.  

The cylinder head gasket used on the 4.0L engine is a composition gasket. The gasket is to be installed dry. Do not use gasket sealing compound on the gasket.

  1. Place the cylinder head gasket over the engine with the numbers facing up.
  2.  
  3. With the No. 14 bolt held in place (tape around the bolt), install the cylinder head. Remove the tape from bolt No 14.
  4.  
  5. Coat the threads of stud bolt No. 11 only, with Loctite 592 sealant or equivalent.
  6.  
  7. Tighten the bolts in the sequence shown in the illustration to the following:
    1. Tighten bolts 1 through 14 in sequence to 22 ft. lbs. (30 Nm).
    2.  
    3. Tighten bolts 1 through 14 in sequence to 45 ft. lbs. (61 Nm).
    4.  
    5. Recheck bolts 1 through 14 in sequence to verify that they are 45 ft. lbs. (61 Nm).
    6.  
    7. Tighten bolts 1 through 10 in sequence to 110 ft. lbs. (149 Nm).
    8.  
    9. Tighten bolt 11 to 100 ft. lbs. (136 Nm).
    10.  
    11. Tighten bolts 12 through 14 to 110 ft. lbs. (149 Nm).
    12.  

  8.  

During the final tightening sequence, bolt No. 11 will be tightened to a lower torque than the rest of the bolts. Do not overtighten bolt No. 11.

  1. Connect the temperature sending unit wire.
  2.  
  3. Install the spark plugs.
  4.  
  5. Install the compressor.
  6.  
  7. Install the compressor/alternator bracket mounting bolt.
  8.  
  9. Adjust the alternator drive belt.
  10.  
  11. Install the air conditioning compressor drive belt.
  12.  
  13. Install the intake and exhaust manifolds.
  14.  
  15. Install the power steering pump bracket.
  16.  
  17. Install the pushrods. Keep them in order!
  18.  
  19. Install the rocker arms. Keep them in order!
  20.  
  21. Thoroughly clean the mating surfaces of the head and rocker cover and install as outlined earlier in this section.
  22.  
  23. Install the air cleaner.
  24.  
  25. Connect the hoses at the thermostat housing.
  26.  
  27. Connect the battery ground.
  28.  
  29. Fill the cooling system.
  30.  

4.2L Engine

See Figure 12

  1. Drain the cooling system and disconnect the hoses at the thermostat housing.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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 cylinder head cover (valve cover), the gasket, the rocker arm assembly, and the pushrods.
  2.  

The pushrods must be replaced in their original positions.

  1. Remove the intake and exhaust manifold from the cylinder head.
  2.  
  3. Disconnect the spark plug wires and the spark plugs to avoid damaging them.
  4.  
  5. Disconnect the temperature sending unit wire, ignition coil and bracket assembly from the engine.
  6.  
  7. Remove the cylinder head bolts, the cylinder head and gasket from the block.
  8.  
  9. Thoroughly clean the gasket mating surfaces. Remove all traces of old gasket material. Remove all carbon deposits from the combustion chambers. Lay a straightedge across the head and check for flatness. Total deviation should not exceed 0.001 in. (0.025mm).
  10.  

To install:
  1. Do not apply sealant to the head or block. Coat both sides of the gasket with sealer. The gasket should be stamped TOP for installation. Place the gasket on the block.
  2.  
  3. Install the head on the block. Insert the bolts and tighten them, in sequence, to the proper torque, in three progressive passes. Torque all bolts to 85 ft. lbs. (115 Nm), except No. 11 in the torque sequence, which should be coated with sealer and torqued to 75 ft. lbs. (102 Nm).
  4.  
  5. Connect the temperature sending unit wire, ignition coil and bracket assembly at the engine.
  6.  
  7. Install the spark plugs and connect the spark plug wires.
  8.  
  9. Install the intake and exhaust manifold on the cylinder head.
  10.  
  11. Install the the rocker arm assembly, and the pushrods.
  12.  

The pushrods must be replaced in their original positions.

  1. Install the cylinder head cover (valve cover) and the gasket.
  2.  
  3. Connect the hoses at the thermostat housing.
  4.  
  5. Fill the cooling system.
  6.  

 
label.common.footer.alt.autozoneLogo