Chevrolet Full Size Cars 1979-1989

Cylinder Head

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REMOVAL & INSTALLATION





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Fig. Fig. 1 Remove the exhaust manifold from the cylinder head



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Fig. Fig. 2 When removing the pushrods, be sure to tag or arrange them to assure proper installation



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Fig. Fig. 3 With the fasteners removed, grasp the cylinder head and lift it from the block



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Fig. Fig. 4 Remove and discard the old head gasket



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Fig. Fig. 5 Carefully clean all remaining gasket material from the mating surfaces



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Fig. Fig. 6 During installation, be sure to use a torque wrench to assure proper seal

The engine should be allowed to cool overnight before the cylinder head is removed in order to prevent warpage.

Inline 6-Cylinder


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Fig. Fig. 7 Cylinder head bolt torque sequence inline 6-cylinder engine

  1. Disconnect the negative battery cable.
  2.  
  3. Drain engine cooling system, then remove air cleaner assembly and disconnect the PCV hose.
  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. Disconnect accelerator pedal rod at the bellcrank on the manifold, then the fuel and the vacuum lines at the carburetor.
  2.  
  3. Disconnect the exhaust pipe at the manifold flange, then remove the manifold bolts and clamps. Remove the exhaust manifold from the engine.
  4.  
  5. Remove the fuel and the vacuum line retaining clip from the water outlet. Disconnect the wiring harness from the temperature sending unit and the coil, leaving the harness clear of the clips on the rocker arm cover.
  6.  
  7. Disconnect the radiator hose at the water outlet housing and the negative battery cable from the cylinder head.
  8.  
  9. Tag and disconnect the wires, then remove the spark plugs.
  10.  
  11. Remove the rocker arm cover, then back off the rocker arm nuts. Pivot the rocker arms to clear the push rods and remove the push rods.
  12.  
  13. Remove the cylinder head bolts, the cylinder head and the gasket.
  14.  
  15. Using a putty knife, clean the gasket mounting surfaces.
  16.  

To install:

  1. Position a new cylinder head gasket on the block, then carefully lower the cylinder head assembly into position.
  2.  
  3. Lubricate the cylinder head bolts using clean engine oil, then install and finger-tighten them. Torque the bolts using the proper torque sequence.
  4.  
  5. Install the push rods, then pivot the rocker arms into position and install the retaining nuts. Adjust the valves and install the rocker arm covers.
  6.  
  7. Install the spark plugs, then connect the wires as noted during removal.
  8.  
  9. Connect the radiator hose at the water outlet housing and the negative battery cable to the cylinder head.
  10.  
  11. Connect the wiring harness to the temperature sending unit and the coil, making sure the harness is properly positioned in the clips of the rocker arm cover (unless equipped with solid lifters).
  12.  
  13. Connect the fuel and the vacuum line retaining clip to the water outlet.
  14.  
  15. Install the exhaust manifold.
  16.  
  17. Connect the accelerator pedal rod at the bellcrank on the manifold, then connect the fuel and the vacuum lines at the carburetor.
  18.  
  19. Install the air cleaner assembly and connect the PCV hose.
  20.  
  21. Connect the negative battery cable and properly refill the engine cooling system
  22.  
  23. Run the engine and check for leaks.
  24.  

V6 and V8 Gasoline Engines (Except 231 V6)


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Fig. Fig. 8 Cylinder head bolt torque sequence V6 engines, except the Buick 231



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Fig. Fig. 9 Cylinder head bolt torque sequence Oldsmobile produced 307 V8 engine

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the intake manifold from the cylinder heads. Refer to the Intake Manifold Removal and Installation procedures earlier in this section for details.
  4.  
  5. If necessary, remove the alternator's lower mounting bolt and reposition the unit aside.
  6.  
  7. Remove the exhaust manifold(s) and the rocker arm cover(s), then remove the rocker arm and pushrod assemblies.
  8.  

If rocker arms and pushrods are to be reused, be sure to sort or label all parts to assure installation in their original locations.

  1. If equipped and necessary, remove the air injection manifold assemblies and/or the diverter valve.
  2.  
  3. Gradually loosen and remove the cylinder head bolts, then remove the cylinder head(s) from the engine block. If necessary, a prybar may be used to gently loosen the gasket seal, but be VERY careful not to damage the sealing surfaces or the engine or cylinder head. Always protect surfaces being pried using wood or cloth.
  4.  
  5. Using a putty knife, clean the gasket mounting surfaces.
  6.  

To install:

  1. Position a new cylinder head gasket on the block, then carefully lower the cylinder head assembly into position.
  2.  
  3. On the 307 Oldsmobile produced engine, be sure to coat the cylinder head retaining bolts with clean engine oil prior to installation.
  4.  
  5. Install and finger-tighten the cylinder head retaining bolts, then tighten them to specification using the proper torque sequence.
  6.  
  7. If removed, install the diverter valve and/or air injection manifold assemblies.
  8.  
  9. Install the pushrod and rocker arm assemblies, then adjust the valves.
  10.  
  11. Install the rocker arm cover(s).
  12.  
  13. Install the exhaust manifold(s) using new gaskets.
  14.  
  15. Install the intake manifold assembly.
  16.  
  17. If not done already, reposition and secure the alternator, then adjust the drive belt.
  18.  
  19. Connect the negative battery cable, then properly refill the engine cooling system.
  20.  
  21. Run the engine and check for leaks.
  22.  

231 V6 Engine


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Fig. Fig. 10 Cylinder head torque sequence 231 V6

On vehicles equipped with AIR, disconnect the rubber hose at the injection tubing check valve. This way the tubing will not have to be removed from the exhaust manifold.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the intake manifold from the engine. Refer to the Intake Manifold Removal and Installation procedures earlier in this section for details.
  4.  
    1. Loosen and remove all drive belts.
    2.  
    3. Tag and disconnect the wires leading from the rear of the alternator.
    4.  
    5. Remove the air conditioning compressor (if so equipped) and position it out of the way with all the hoses still connected.
    6.  
    7. Remove the alternator and its mounting bracket.
    8.  

  5. When removing the left cylinder head:
  6.  
    1. Remove the oil gauge rod.
    2.  
    3. Remove the power steering pump (if so equipped) and its bracket and then position it out of the way with the hoses still attached.
    4.  

  7. Tag and disconnect the spark plug wires and then remove the spark plug wires clips from the cylinder head cover studs.
  8.  
  9. Remove the exhaust manifold mounting bolts from the head which is being removed, and then pull the manifold away from the head.
  10.  
  11. Use an air hose if available, or a bunch of clean rags and clean the dirt off the head and surrounding areas thoroughly. It is extremely important to avoid getting dirt into the hydraulic valve lifters.
  12.  
  13. Remove the rocker arm cover from the top of the head that you wish to remove.
  14.  
  15. Remove the rocker arm and shaft assembly from the cylinder head and then remove the pushrods.
  16.  

If the valve lifters are to be serviced, remove them at this time. Otherwise, protect the lifters and the camshaft from dust and dirt by covering the entire area with a clean cloth. Whenever the lifters or the pushrods are removed from the head it is always a good idea to place them in a wooden block with numbered holes to keep them identified as to their position in the engine.

  1. Loosen and remove all the cylinder head bolts, then then lift the head off the engine block.
  2.  

To install:

  1. Clean the engine block gasket surface thoroughly. Make sure that no foreign material has fallen into the cylinder bores, the bolt holes or into the valve lifter area. It is always a good idea to clean out the bolt holes with an air hose if one is available.
  2.  
  3. Install a new head gasket with the bead facing down toward the cylinder block. The dowels in the block will hold the gasket in place.
  4.  
  5. Clean the gasket surface of the cylinder head and carefully set it into place on the dowels in the cylinder block.
  6.  
  7. Use a heavy body thread sealer on all of the head bolts since the bolt holes go all the way through into the coolant.
  8.  
  9. Install the head bolts. Tighten the bolts a little at a time about three times around in the sequence shown in the illustration. Tighten the bolts to a final torque equal to that given in the Torque Specifications chart.
  10.  

On vehicles equipped with solid lifters, once the valves have been set up properly and given a static adjustment, temporarily place the rocker arm cover on the engine to prevent the entrance of dirt or debris. After the valves have been adjusted with the engine running (dynamic adjustment), the cover will be fastened in place.

  1. Install the pushrod and rocker arm assemblies, then adjust the valves.
  2.  
  3. Install the rocker arm cover(s).
  4.  
  5. Reposition and secure the exhaust manifold.
  6.  
  7. Route the spark plug wires through the retaining clips and connect them to the plugs, as noted during removal.
  8.  
  9. If the left cylinder head was removed, reposition and secure the power steering pump, then install the oil gauge rod.
  10.  
  11. Install the intake manifold assembly.
  12.  
  13. Connect the negative battery cable and properly refill the engine cooling system.
  14.  
  15. Run the engine and check for leaks.
  16.  

Diesel Engine


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Fig. Fig. 11 Cylinder head torque sequence 350 V8 diesel engine

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the intake manifold. Refer to the procedure earlier in this section for details.
  4.  
  5. Remove the rocker arm cover(s), after removing any accessory brackets which interfere with cover removal.
  6.  
  7. Tag and disconnect the glow plug wiring.
  8.  
  9. If the right cylinder head is being removed, disconnect the ground strap from the head.
  10.  
  11. Remove the rocker arm bolts, the bridged pivots, the rocker arms, and the pushrods, keeping all the parts in order so that they can be returned to their original locations. It is a good practice to number or mark the parts to avoid interchanging them.
  12.  
  13. Remove the fuel return lines from the nozzles.
  14.  
  15. Remove the exhaust manifold(s). Refer to the procedure earlier in this section for details.
  16.  
  17. Remove the engine block drain plug on the side of the engine from which the cylinder head is being removed. On V6s, remove the pipe thread plugs covering the upper cylinder head bolts.
  18.  
  19. Remove the head bolts, then remove the cylinder head assembly.
  20.  

To install:

  1. Clean the mating surfaces thoroughly. Install new head gaskets on the engine block. DO NOT coat the gaskets with any sealer. The gaskets have a special coating that eliminates the need for sealer. The use of sealer will interfere with this coating and cause leaks. Install the cylinder head onto the block.
  2.  
  3. Clean the head bolts thoroughly. Dip the bolts in clean engine oil and install into the cylinder block until the heads of the bolts lightly contact the cylinder head.
  4.  
  5. Tighten the bolts, in the sequence illustrated, to 100 ft. lbs. (136 Nm). When all bolts have been tightened to this figure, begin the tightening sequence again, and torque all bolts to 130 ft. lbs. (176 Nm).
  6.  
  7. Install the engine block drain plug(s), the exhaust manifold(s), the fuel return lines, the glow plug wiring, and the ground strap for the right cylinder head.
  8.  
  9. Install the valve train assembly. Refer to diesel engine, rocker arm replacement, earlier in this section, for valve lifter bleeding procedures.
  10.  
  11. Install the intake manifold.
  12.  
  13. Install the rocker cover(s). The valve covers are sealed with RTV (room temperature vulcanizing) silicone sealer instead of a gasket. Use GM No. 1052434 or its equivalent. Install the cover to the head within 10 minutes (while the sealer is still wet).
  14.  
  15. Connect the negative battery cable and properly refill the engine cooling system.
  16.  

CLEANING AND INSPECTION





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Fig. Fig. 12 Exploded view of a common cylinder head assembly Small block Chevrolet V8 engine shown

Any diesel cylinder head work should be handled by a reputable machine shop familiar with diesel engines. Disassembly, valve lapping, and assembly can be completed by following the gasoline engine procedures.

Gasoline Engines
REMOVING GASKET MATERIAL AND CARBON DEPOSITS


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Fig. Fig. 13 Use a gasket scraper to remove the bulk of the old head gasket from the mating surface



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Fig. Fig. 14 An electric drill equipped with a wire wheel will expedite complete gasket removal



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Fig. Fig. 15 The electric drill and wire brush may also be used to remove carbon deposits from the tops of the combustion chambers

Once the complete valve train has been removed from the cylinder head(s), the head itself can be inspected, cleaned and machined (if necessary). Set the head(s) on a clean work space, so the combustion chambers are facing up. Begin cleaning the gasket surface, chambers and ports with a hardwood chisel or other non-metallic tool (to avoid nicking or gouging the chamber, ports, and especially the valve seats). Chip away the gasket material and the major carbon deposits, then remove the remainder with a wire brush fitted to an electric drill.

Be sure that the carbon is actually removed, rather than just burnished. After decarbonizing is completed, take the head(s) to a machine shop and have the head hot tanked (unless they are aluminum). In this process, the head is lowered into a hot chemical bath that very effectively cleans all grease, corrosion, and scale from all internal and external head surfaces. Also have the machinist check the valve seats and re-cut them if necessary. When you bring the clean head(s) home, place them on a clean surface. Completely clean the entire valve train with solvent.

CHECKING FOR HEAD WARPAGE


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Fig. Fig. 16 Check the cylinder head for warpage along the center using a straightedge and a feeler gauge



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Fig. Fig. 17 Be sure to check for warpage across the cylinder head at both diagonals

Lay the head down with the combustion chamfers facing up. Place a straightedge across the gasket surface of the head, both diagonally and straight across the center. Using a flat feeler gauge, determine the clearance at the center of the straightedge. If warpage exceeds 0.003 in. within a 6 in. span, or 0.006 inch over the total length, the cylinder head must be resurfaced (which is akin to planing a piece of wood). Resurfacing can be performed at most machine shops.

When resurfacing the cylinder head(s) of V6 or V8 engines, the intake manifold mounting position is altered, and must be corrected by machining a proportionate amount from the intake manifold flange.

LAPPING THE VALVES


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Fig. Fig. 18 Home-made valve lapping tool



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Fig. Fig. 19 Lapping the valves by hand

When valve faces and seats have been refaced and recut, or if they are determined to be in good condition, the valves must be lapped in to ensure efficient sealing when the valves closes against the seal.

  1. Invert the cylinder head so that the combustion chambers are facing up.
  2.  
  3. Lightly lubricate the valve stems with clean oil, and coat the valve seats with valve grinding compound. Install the valves in the head as numbered.
  4.  
  5. Attach the suction cup of a valve lapping tool to a valve head. You'll probably have to moisten the cup to securely attach the tool to the valve.
  6.  
  7. Rotate the tool between the palms, changing position and lifting the tool often to prevent grooving. Lap the valve until a smooth, polished seat is evident (you may have to add a bit more compound after some lapping is done).
  8.  
  9. Remove the valve and tool, and remove ALL traces of grinding compound with solvent-soaked rag, or rinse the head with solvent.
  10.  

Valve lapping can also be done by fastening a suction cup to a piece of drill rod in a hand eggbeater type drill. Proceed as above, using the drill as a lapping tool. Due to the higher speeds involved when using the hand drill, care must be exercised to avoid grooving the seat. Lift the tool and change direction of rotation often.

RESURFACING



This procedure should only be performed by a qualified machine shop.

 
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