AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Cylinder Head

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REMOVAL & INSTALLATION





Don't loosen the head bolts until the engine is thoroughly cool, to prevent warping. Do not remove block drain plugs or loosen radiator draincock with the system hot and under pressure, as serious burns from coolant can occur.
 
If the head sticks, operate the starter to loosen it by compression or rap it upward with a soft hammer. Do not force anything between the head and the block.
 
Resurfacing (milling or grinding) the cylinder head will increase the compression ratio, and can affect the emission output, as well as the fuel octane requirement. For this reason the factory recommends replacing rather than resurfacing cylinder heads.
 
Cylinder heads bolts should be retorqued after the first 500 miles or so unless a special AMC gasket is used. The special gasket doesn't require retorquing.
 
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 information.
 
Make sure to blow any coolant out of the cylinder head bolt holes before reassembly to prevent inaccurate torque readings.
 

4-121 Engine See Figure 1

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Fig. Fig. 1: Cylinder head bolt tightening sequence4-121 engine

  1. Drain the coolant from the system and disconnect the negative cable from the battery.
  2.  


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

  1. Remove the air cleaner assembly, vacuum hoses and flexible hoses from the cylinder head area.
  2.  
  3. Remove the radiator hoses, radiator bypass hose and the heater hoses.
  4.  
  5. Remove the accessory drive belts, camshaft drive belt cover, and the camshaft drive belt. Loosen the compressor mounting bracket if equipped with A/C.
  6.  
  7. Remove the fan belt, fan blades, spacer and pulley. Remove the air pump and also the alternator pivot bolt. Do not disconnect the wire harness from the alternator.
  8.  
  9. Remove the air pump front bracket, and the exhaust pipe from the manifold. Remove the air hose from the diverter valve and remove the EGR tube to bell housing screw.
  10.  
  11. Disengage the remaining wires to the electrical units of the cylinder head, marking the wires for connection during assembly.
  12.  
  13. Disengage the fuel line at the bottom of the intake manifold, and remove the screw from the bottom of the manifold bracket.
  14.  
  15. Disconnect the power brake vacuum hose. Remove the remaining fuel vapor control hoses, PCV hoses and the remaining vacuum lines.
  16.  
  17. Disconnect the accelerator cable.
  18.  
  19. Remove the coolant inlet and outlet hoses from the intake manifold.
  20.  
  21. Remove the cylinder head cover. Loosen and remove the head bolts. Loosen the bolts in the reverse order of the tightening sequence, in two passes. Remove the cylinder head, manifolds and carburetor as a unit.
  22.  
  23. Clean the machined surfaces of the cylinder head and the engine block. With a straight edge and feeler gauge, check the flatness of the mating surfaces. There should not be a distortion of over 0.002 in. (0.051mm) on both surfaces.
  24.  
  25. After the necessary services have been done to the cylinder head and/or the block assembly, prepare the mating surfaces by cleaning thoroughly.
  26.  


CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your hands and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used.

To install:
  1. Install a new head gasket, and place the head on the block with the aid of locating dowels. Torque the cylinder head according to the torque sequence illustration, and in three stages.
  2.  
  3. Install the coolant inlet and outlet hoses on the intake manifold.
  4.  
  5. Connect the accelerator cable.
  6.  
  7. Connect the power brake vacuum hose. Install the fuel vapor control hoses, PCV hoses, and the vacuum lines.
  8.  
  9. Attach the fuel line at the bottom of the intake manifold, and install the screw in the bottom of the manifold bracket.
  10.  
  11. Connect the wires to the electrical units of the cylinder head.
  12.  
  13. Install the air pump front bracket, and the exhaust pipe at the manifold. Install the air hose at the diverter valve and install the EGR tube-to-bell housing screw.
  14.  
  15. Install the fan belt, fan blades, spacer and pulley. Install the air pump and also the alternator pivot bolt.
  16.  
  17. Install the accessory drive belts, camshaft drive belt cover, and the camshaft drive belt.
  18.  
  19. Install the radiator hoses, radiator bypass hose and the heater hoses.
  20.  
  21. Install the air cleaner assembly, vacuum hoses and flexible hoses at the cylinder head area.
  22.  
  23. Fill the cooling system and connect the negative battery cable.
  24.  
  25. Temporarily install the head cover. Start the engine and allow it to warm up for five minutes.
  26.  
  27. When the engine has warmed up to operating temperature, stop the engine and remove the top engine cover.
  28.  
  29. Following the head torque sequence, loosen the first head bolt 1 / 8 of a turn and retorque the bolt to 80 ft.lb. Proceed to the second bolt and repeat the procedure for each head bolt until all the bolts have been retorqued to the new specification.
  30.  
  31. Check the engine for leakage.
  32.  

4-150 Engine See Figures 2 and 3

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Fig. Fig. 2: Cylinder head bolt tightening sequence4-150 engine



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Fig. Fig. 3: Some head bolts on 4-150 engines are defective. If they are broken they must be replaced

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


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

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.

  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. (0.0254mm).
  2.  

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.
  4.  
  5. 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.lb. Torque #8 to 75 ft.lb.
  6.  
  7. Connect the temperature sending unit wire.
  8.  
  9. Install the spark plugs.
  10.  
  11. Install the compressor.
  12.  
  13. Install the compressor/alternator bracket mounting bolt.
  14.  
  15. Adjust the alternator drive belt.
  16.  
  17. Install the air conditioning compressor drive belt.
  18.  
  19. Install the intake and exhaust manifolds.
  20.  
  21. Install the power steering pump bracket.
  22.  
  23. Install the pushrods. Keep them in order!
  24.  
  25. Install the rocker arms. Keep them in order!
  26.  
  27. Thoroughly clean the mating surfaces of the head and rocker cover. Run a 1 / 8 in. (3.175mm) 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 in.lb.
  28.  
  29. Install the air cleaner.
  30.  
  31. Connect the hoses at the thermostat housing.
  32.  
  33. Connect the battery ground.
  34.  
  35. Fill the cooling system.
  36.  

4-151 Engine See Figure 4

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Fig. Fig. 4: Cylinder head bolt tightening sequence4-151 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.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze and could 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.  
  3. Remove the intake and exhaust manifold from the cylinder head.
  4.  
  5. Disconnect the spark plug wires and remove the spark plugs to avoid damaging them.
  6.  
  7. Disconnect the temperature sending unit wire, ignition coil and bracket assembly and battery ground cable from the engine.
  8.  
  9. Remove the cylinder head bolts, the cylinder head and gasket from the block.
  10.  
  11. 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. (0.0254mm).
  12.  

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 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.
  4.  
  5. Install the pushrods and the rocker arm assembly.
  6.  
  7. Install the intake and exhaust manifold on the cylinder head.
  8.  
  9. Install the spark plugs and connect the spark plug wires.
  10.  
  11. Connect the temperature sending unit wire, ignition coil and bracket assembly and battery ground cable at the engine.
  12.  
  13. Connect the hoses at the thermostat housing.
  14.  
  15. Thoroughly clean the mating surfaces of the head and rocker cover. Run a 1 / 8 in. (3.175mm) 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 in.lb.
  16.  
  17. Fill the cooling system.
  18.  

6-232 and 258 Engines See Figure 5

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Fig. Fig. 5: Cylinder head bolt tightening sequence6-cylinder engines

On Pacers, run the wipers to the center of the windshield to ease valve cover removal.

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


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

If equipped with power steering, remove the power steering pump bracket and air guard pump and set them aside. Don't disconnect the hoses.

  1. Disconnect the spark plug wires and the spark plugs to avoid damaging them.
  2.  
  3. Disconnect the temperature sending unit wire, ignition coil and bracket assembly from the engine.
  4.  

If the vehicle is equipped with air conditioning, remove the drive belt idler pulley bracket from the cylinder head. Loosen the alternator drive belt and remove the bolts from the compressor mounting bracket. Set the compressor aside, all hoses attached.

  1. Remove the cylinder head bolts, the cylinder head and gasket from the block.
  2.  

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. (0.0254mm).
  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, 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.
  6.  

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.  

8-304, 360 and 401 Engines See Figures 6 through 14

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Fig. Fig. 6: Cylinder head bolt tightening sequenceV8 engines



Click image to see an enlarged view

Fig. Fig. 7: Unfasten the cylinder head bolts in the designated bolts ...



Click image to see an enlarged view

Fig. Fig. 8: ... then remove the cylinder head from the engine block



Click image to see an enlarged view

Fig. Fig. 9: Remove the cylinder head gasket ...



Click image to see an enlarged view

Fig. Fig. 10: ... then use a scraper to remove any remaining gasket material



Click image to see an enlarged view

Fig. Fig. 11: Use a torque wrench to tighten the cylinder head bolts in sequence to the proper specification



Click image to see an enlarged view

Fig. Fig. 12: Use a gasket scraper to remove the bulk of the old head gasket from the mating surface



Click image to see an enlarged view

Fig. Fig. 13: An electric drill equipped with a wire wheel will expedite complete gasket removal



Click image to see an enlarged view

Fig. Fig. 14: Check the cylinder head for warpage along the center using a straightedge and a feeler gauge

  1. Drain the cooling system and cylinder block.
  2.  


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

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

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.  


CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your hands and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used.

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. (0.0254mm).
  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, in three progressive passes. Torque all bolts to 80 ft.lb.
  6.  
  7. Connect the air pump and power steering pump brackets to the left cylinder head.
  8.  
  9. Connect the battery ground cable and alternator bracket to the right cylinder head.
  10.  
  11. Adjust all of the drive belts.
  12.  
  13. 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.
  14.  
  15. Install the intake manifold with the carburetor still attached.
  16.  
  17. Install the spark plugs.
  18.  
  19. Install the rocker arm assemblies and the pushrods.
  20.  

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.  

 
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