Jeep CJ/Scrambler 1971-1986 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



See Figures 1 through 14

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.

4-134 Engine
  1. Drain the coolant.
  2.  
  3. Remove the upper radiator hose.
  4.  
  5. Remove the carburetor.
  6.  
  7. Remove the rocker arm cover.
  8.  
  9. Remove the rocker arm attaching stud nuts and rocker arm shaft assembly.
  10.  
  11. Remove the cylinder head bolts. One of the bolts is located below the carburetor mounting, inside the intake manifold.
  12.  
  13. Lift off the cylinder head.
  14.  
  15. 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).
  16.  

To install:
  1. Position the head on the block.
  2.  
  3. Tighten the head bolts first to 40 ft. lbs. then to the specified torque in the correct sequence.
  4.  
  5. Install the rocker arm shaft assembly.
  6.  
  7. Install the rocker arm cover.
  8.  
  9. Install the carburetor.
  10.  
  11. Install the upper radiator hose.
  12.  
  13. Fill the cooling system.
  14.  



Click image to see an enlarged view

Fig. Fig. 1: Cylinder head torque sequence on the 4-134 engine

4-150 Engine
  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  
  5. Disconnect the hoses at the thermostat housing.
  6.  
  7. Remove the air cleaner.
  8.  
  9. 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.
  10.  
  11. Remove the rocker arms. Keep them in order!
  12.  
  13. Remove the pushrods. Keep them in order!
  14.  
  15. Remove the power steering pump bracket.
  16.  
  17. Suspend the pump out of the way.
  18.  
  19. Remove the intake and exhaust manifolds.
  20.  
  21. Remove the air conditioning compressor drive belt.
  22.  
  23. Loosen the alternator drive belt.
  24.  
  25. Remove the compressor/alternator bracket mounting bolt.
  26.  
  27. Unbolt the compressor and suspend it out of the way. DO NOT DISCONNECT THE REFRIGERANT LINES!
  28.  
  29. Remove the spark plugs.
  30.  
  31. Disconnect the temperature sending unit wire.
  32.  
  33. Remove the head bolts.
  34.  
  35. Lift the head off the engine and place it on a clean workbench.
  36.  
  37. Remove the head gasket.
  38.  

Some head bolts used on the spark plug side of the 1984 4-150 were improperly hardened and may break under the head during service or at head installation while torquing the bolts. Engines with the defective bolts are serial numbers 310U06 through 310U14. Whenever a broken bolts is found, replace all bolts on the spark plug side of the head with bolt #400 6593.

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 bolt labeled 8 in the torque sequence illustration, with Permatex #2, or equivalent. Install all the bolts. Tighten the bolts in three equal steps, in the sequence shown, to 85 ft. lbs. Torque #8 to 75 ft. lbs.
  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.
  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.  



Click image to see an enlarged view

Fig. Fig. 2: Cylinder head bolt torque sequence on the 4-150 engine

4-151 Engine

The 4-151 rocker cover is sealed with RTV silicone gasket material. Do not use a conventional gasket.

  1. Drain the cooling system and disconnect the hoses at the thermostat housing.
  2.  
  3. Remove the cylinder head cover (valve cover), the gasket, the rocker arm assembly, and the pushrods.
  4.  
  5. Remove the intake and exhaust manifold from the cylinder head.
  6.  
  7. Disconnect the spark plug wires and remove the spark plugs to avoid damaging them.
  8.  
  9. Disconnect the temperature sending unit wire, ignition coil and bracket assembly and battery ground cable from the engine.
  10.  
  11. Remove the cylinder head bolts, the cylinder head and gasket from the block.
  12.  
  13. 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).
  14.  

To install:
  1. 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, inboard of the bolt holes. 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.
  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. Insert the bolts and tighten them, in sequence, to the proper torque.
  6.  
  7. Install the pushrods and the rocker arm assembly.
  8.  
  9. Install the intake and exhaust manifold on the cylinder head.
  10.  
  11. Install the spark plugs and connect the spark plug wires.
  12.  
  13. Connect the temperature sending unit wire, ignition coil and bracket assembly and battery ground cable at the engine.
  14.  
  15. Connect the hoses at the thermostat housing.
  16.  
  17. Fill the cooling system.
  18.  



Click image to see an enlarged view

Fig. Fig. 3: Cylinder head torque sequence on the 4-151 engine

6-225 Engine
  1. Drain the cooling system.
  2.  
  3. Remove the intake manifold.
  4.  
  5. Remove the rocker cover.
  6.  
  7. Remove the exhaust pipes at the flanges.
  8.  
  9. Remove the alternator in order to remove the right head.
  10.  
  11. Remove the dipstick and power steering pump, if so equipped, in order to remove the left head.
  12.  
  13. Remove the valve cover and the rocker assemblies. Mark these parts so that they can be reinstalled in exactly the same positions.
  14.  
  15. Unbolt the head bolts and lift off the cylinder head(s). It is very important that the inside of the engine be protected from dirt. The hydraulic lifters are particularly susceptible to being damaged by dirt.
  16.  
  17. 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).
  18.  

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 65-85 ft. lbs., in three progressive passes.
  4.  
  5. Install the rocker assemblies and the valve covers. Torque the rocker arm assemblies to 25-35 ft. lbs.; the valve covers to 36-60 in. lbs.
  6.  
  7. Install the dipstick and power steering pump, if so equipped.
  8.  
  9. Install the alternator. Torque the bracket-to-head bolts to 30-40 ft. lbs.; the bracket to water pump bolts to 18-25 ft. lbs.
  10.  
  11. Install the exhaust pipes at the flanges. Torque the nuts to 20 ft. lbs.
  12.  
  13. Install the intake manifold. Torque the bolts to 45-55 ft. lbs.
  14.  
  15. Fill the cooling system.
  16.  



Click image to see an enlarged view

Fig. Fig. 4: Cylinder head torque sequence on the 6-225 engine

6-232 and 6-258 Engines
  1. Drain the cooling system and disconnect the hoses at the thermostat housing.
  2.  
  3. Remove the cylinder head cover (valve cover), the gasket, the rocker arm assembly, and the pushrods.
  4.  

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., except #11 in the torque sequence, which should be coated with sealer and torqued to 75 ft. lbs.
  4.  

Some head bolts used on the spark plug side of the 1984 6-258 were improperly hardened and may break under the head during service or at head installation while torquing the bolts. Engines with the defective bolts are serial numbers 310C06 through 310C14. Whenever a broken bolts is found, replace all seven bolts on the spark plug side of the head with bolt #400 6593.

  1. Connect the temperature sending unit wire, ignition coil and bracket assembly at the engine.
  2.  
  3. Install the spark plugs and connect the spark plug wires.
  4.  
  5. Install the intake and exhaust manifold on the cylinder head.
  6.  
  7. Install the the rocker arm assembly, and the pushrods.
  8.  

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.  



Click image to see an enlarged view

Fig. Fig. 5: Cylinder head torque sequence on the 6-232 and 6-258 engines



Click image to see an enlarged view

Fig. Fig. 6: Cylinder head torque sequence on the 8-304 engine

8-304 Engine
  1. Drain the cooling system and cylinder block.
  2.  
  3. When removing the right cylinder head, it may be necessary to remove the heater core housing from the firewall.
  4.  
  5. Remove the valve cover(s) and gasket(s).
  6.  
  7. Remove the rocker arm assemblies and the pushrods.
  8.  

The valve train components must be replaced in their original positions.

  1. Remove the spark plugs to avoid damaging them.
  2.  
  3. Remove the intake manifold with the carburetor still attached.
  4.  
  5. Remove the exhaust pipes at the flange of the exhaust manifold. When replacing the exhaust pipes it is advisable to install new gaskets at the flange.
  6.  
  7. Loosen all of the drive belts.
  8.  
  9. Disconnect the battery ground cable and alternator bracket from the right cylinder head.
  10.  
  11. Disconnect the air pump and power steering pump brackets from the left cylinder head.
  12.  
  13. Remove the cylinder head bolts and lift the head(s) from the cylinder block.
  14.  
  15. Remove the cylinder head gasket from the head or the block.
  16.  
  17. 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).
  18.  

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.  

Four of the retaining bolts for each cylinder head thread through cylinder water jackets. Although the manufacturer does not specifically address these bolts, experience has shown that they must coated with sealant prior to installation in order to prevent leakage.

  1. Install the head on the block. Insert the bolts and tighten them using 2 progressive passes of the proper sequence. For the first pass tighten the bolts to 80 ft. lbs. On the final pass, tighten the bolts to 110 ft. lbs.
  2.  
  3. Connect the air pump and power steering pump brackets to the left cylinder head.
  4.  
  5. Connect the battery ground cable and alternator bracket to the right cylinder head.
  6.  
  7. Adjust all of the drive belts.
  8.  
  9. Install the exhaust pipes at the flange of the exhaust manifold. When replacing the exhaust pipes it is advisable to install new gaskets at the flange.
  10.  
  11. Install the intake manifold with the carburetor still attached.
  12.  
  13. Install the spark plugs.
  14.  
  15. Install the rocker arm assemblies and the pushrods.
  16.  

The valve train components must be replaced in their original positions.

  1. Install the valve cover(s) and gasket(s).
  2.  
  3. Install the heater core housing on the firewall.
  4.  
  5. Fill the cooling system and cylinder block.
  6.  



Click image to see an enlarged view

Fig. Fig. 7: Removing the inner cylinder head bolts



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Fig. Fig. 8: Removing the outer cylinder head bolts, be sure to remove the bolts in reverse order of the torque sequence



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Fig. Fig. 9: When removing the head bolts, check the condition of the bolt



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Fig. Fig. 10: The push rods must be removed, before the head can be removed



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Fig. Fig. 11: Lift the cylinder head off of the block, use care it is very heavy



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Fig. Fig. 12: Remove the cylinder head gasket from the block, check the block deck



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Fig. Fig. 13: Clean the gasket mating surface



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Fig. Fig. 14: Removing the valve lifter with a magnetic tool

 
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