GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Timing Gear Cover

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6 and 7

Inline 6-Cylinder
  1. Disconnect the negative battery cable.
  2.  
  3. For 1964-72 models, raise and support the vehicle safely using jackstands, then drain the engine oil and remove the oil pan.
  4.  
  5. Drain the engine cooling system, then remove the radiator from the vehicle.
  6.  


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 fan, pulley, and belt. Remove any power steering and/or AIR pump drive belts. Remove any braces for the above pumps which will interfere with cover removal and position the pumps out of the way.
  2.  
  3. Remove the crankshaft pulley and damper. Use the puller tool No. J-16516 to remove the damper. Do NOT attempt to pry or hammer the damper off, or it will be damaged.
  4.  
  5. Remove the retaining bolts, then for 1964-72 models, remove the front cover.
  6.  
  7. On 1973-79 models, pull the cover forward slightly and cut the oil pan front seal off flush with the block. Remove the cover. On installation, be sure to cut the tabs off a new oil pan front seal and install it on the cover.
  8.  

To install:
  1. Thoroughly clean the gasket mating surfaces, then check and if necessary, replace the front cover oil seal.
  2.  
  3. Install the front cover to the engine using a new gasket. Coat the gasket with sealer and use a 1 / 8 in. bead of silicone sealer at the oil pan-to-cylinder block joint. Install the damper before tightening the cover bolts down, so that the cover seal will align. The damper must be drawn into place as hammering it into position will likely destroy it.
  4.  

When installing the timing cover, place the centering tool J-23042 inside the oil seal, slide the timing cover into position, install 2 screws and remove the tool.

  1. Install any braces for the power steering and/or AIR pumps which were removed for access.
  2.  
  3. Install the engine cooling fan and pulley, then install the drive belts and adjust their tension.
  4.  
  5. Install the radiator to the vehicle.
  6.  
  7. If removed, install the oil pan, then remove the jackstands and carefully lower the vehicle.
  8.  
  9. Check and add clean engine oil, as necessary.
  10.  
  11. Connect the negative battery cable, then properly fill the engine cooling system.
  12.  



Click image to see an enlarged view

Fig. Fig. 1: On most applications the front cover must be carefully guided into place in order to assure a proper seal between the cover and the oil pan



Click image to see an enlarged view

Fig. Fig. 2: On some applications, the oil pan seal should be cut flush with the front of the engine block

V6 and V8 Except 231
1964-74 (EXCEPT 231)
  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle safely using jackstands, then drain the engine oil.
  4.  
  5. Except for 1974 and later small block engines, remove the oil pan.
  6.  
  7. Drain the engine cooling system and remove the radiator assembly from the vehicle.
  8.  


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 fan, pulley, and belt. Remove any power steering and/or AIR pump drive belts. Remove any braces for these pumps which will interfere with cover removal and position the pumps out of the way.
  2.  
  3. Remove the water pump assembly.
  4.  
  5. Remove the crankshaft pulley and damper. Use a puller on the damper. Do not attempt to pry or hammer the damper off.
  6.  
  7. Remove the retaining bolts, the carefully remove the timing cover from the front of the engine block.
  8.  

To install:
  1. Thoroughly clean the gasket mating surfaces, then check and if necessary, replace the front cover oil seal.
  2.  
  3. Install the front cover to the engine using a new gasket. Apply a 1 / 8 in. bead of silicone rubber sealer to the oil pan and cylinder block joint faces. Lightly coat the bottom of the seal with engine oil.
  4.  
  5. Install the crankshaft damper and pulley to the engine.
  6.  
  7. Install the water pump assembly.
  8.  
  9. Install any braces for the power steering and/or AIR pumps which were removed for access.
  10.  
  11. Install the engine cooling fan and pulley, then install the drive belts and adjust their tension.
  12.  
  13. Install the radiator assembly to the vehicle.
  14.  
  15. If removed, install the oil pan assembly, then remove the jackstands and carefully lower the vehicle.
  16.  
  17. Check and add clean engine oil, as necessary.
  18.  
  19. Connect the negative battery cable, then properly fill the engine cooling system.
  20.  



Click image to see an enlarged view

Fig. Fig. 3: When the timing gear cover is replaced on most engine, the oil pan front seal must be modified



Click image to see an enlarged view

Fig. Fig. 4: Trimming the oil pan seal using a razor blade

1975-88 (EXCEPT 231)
  1. Disconnect the negative battery cable and drain the cooling system.
  2.  


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 fan assembly, the drive belts and the fan pulley.
  2.  
  3. Raise and support the vehicle safely using jackstands.
  4.  
  5. Remove the alternator and the brackets. If equipped with power steering, remove the lower pump bracket and swing aside.
  6.  
  7. Disconnect the heater and the lower radiator hoses from the water pump.
  8.  
  9. Remove the water pump bolts, then remove the pump from the engine.
  10.  
  11. Remove the crankshaft pulley and the damper pulley bolt.
  12.  
  13. Using tool J-23523, remove the damper pulley.
  14.  
  15. Remove the timing cover bolts and carefully remove the timing cover from the front of the engine block.
  16.  

To install:
  1. Thoroughly clean the gasket mating surfaces, then check and if necessary, replace the front cover oil seal.
  2.  
  3. Install the front cover to the engine using a new gasket, then tighten the timing cover retaining bolts to 8 ft. lbs. (11 Nm).
  4.  
  5. Install the crankshaft damper and pulley to the engine.
  6.  
  7. Install the water pump assembly to the engine, then connect the hoses.
  8.  
  9. Install the alternator and brackets to the engine. If equipped with power steering reposition and secure the pump using the lower bracket.
  10.  
  11. Remove the jackstands and carefully lower the vehicle.
  12.  
  13. Install the water pump pulley and fan, then install the drive belts and adjust their tension.
  14.  
  15. Check and add clean engine oil, as necessary.
  16.  
  17. Connect the negative battery cable, then properly refill the engine cooling system.
  18.  



Click image to see an enlarged view

Fig. Fig. 5: Use sealer at the timing cover-to-oil pan and oil pan-to-cylinder block joints



Click image to see an enlarged view

Fig. Fig. 6: On V8 engines, apply sealer to the front pads at the area shown

231 V6
  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system and disconnect the radiator hoses, then remove the radiator.
  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. Loosen and remove all the drive belts, then remove the fan and fan pulley. Remove the bypass hose.
  2.  
  3. Remove the crankshaft pulley, the fuel pump and the distributor. Scribe matchmarks for the distributor housing and rotor before removal.
  4.  
  5. Remove the alternator and its bracket.
  6.  
  7. Remove the harmonic balancer using a suitable damper puller. DO NOT use a jawed-type puller.
  8.  
  9. Remove the two bolts which attach the oil pan to the front cover. Remove the bolts which attach the cover to the block, then carefully remove the cover from the front of the engine.
  10.  

To install:
  1. Thoroughly clean the mating surfaces of any remaining gasket or sealer.
  2.  
  3. Before installing the timing cover it is first necessary to remove the oil pump cover and pack the space around the oil pump gears completely full of petroleum jelly. Do not use gear lube. There must be no air space left inside the pump. Reinstall the pump cover using a new gasket. This step is very important since the oil pump may lose its prime any time the pump, pump cover or timing cover is disturbed. If the pump is not packed, it may not begin to pump oil as soon as the engine is started which could result in serious engine damage.
  4.  
  5. Install the front cover, using a sealer and new gaskets. Make sure the dowel pins engage the dowel pin holes before starting the bolts. Apply sealer to the bolt threads.
  6.  
  7. Install the harmonic balancer, bolt and washer. It will be necessary to lock the flywheel in some way to torque the balancer bolt to specifications. Most mechanics remove the flywheel cover and lock the flywheel with suitable locking device.
  8.  
  9. Install the alternator and bracket assembly.
  10.  
  11. Install the distributor, aligning the matchmarks made earlier for the housing and for the rotor.
  12.  
  13. Install the fuel pump, then install the crankshaft pulley.
  14.  
  15. Connect the bypass hose.
  16.  
  17. Install the water pump fan and pulley, then install the drive belts and adjust their tension.
  18.  
  19. Install the radiator assembly and connect the hoses.
  20.  
  21. Check and add clean engine oil, as necessary.
  22.  
  23. Connect the negative battery cable, then properly refill the engine cooling system.
  24.  



Click image to see an enlarged view

Fig. Fig. 7: Chamfered front cover dowel pin

V6 and V8 Diesel Engines
  1. Drain the cooling system and disconnect the radiator hoses.
  2.  


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 all belts, then remove the water pump fan and pulley.
  2.  
  3. Remove the crankshaft pulley and balancer, using a balancer puller.
  4.  


WARNING
The use of any other type of puller, such as a universal claw type which pulls on the outside of the hub, can destroy the balancer. The outside ring of the balancer is bonded in rubber to the hub. Pulling on the outside will break the bond. The timing mark is on the outside ring. If it is suspected that the bond is broken, check that the center of the keyway is 16 degrees from the center of the timing slot. In addition, there are chiseled aligning marks between the weight and the hub.

  1. Unbolt and remove the cover, timing indicator, water pump and both dowel pins. It may be necessary to grind a flat on the cover for gripping purposes.
  2.  

To install:
  1. Grind a chamfer on one end of each dowel pin.
  2.  
  3. Cut the excess material from the front end of the oil pan gasket on each side of the block.
  4.  
  5. Clean the block, oil pan and front cover mating surfaces with solvent.
  6.  
  7. Trim about 1 / 8 in. off each end of a new front pan seal.
  8.  
  9. Install a new front cover gasket on the block and a new seal in the front cover.
  10.  
  11. Apply an R.T.V. sealer to the gasket around the coolant holes.
  12.  
  13. Apply an R.T.V. sealer to the block at the junction of the pan and front cover.
  14.  
  15. Place the cover on the block and press down to compress the seal. Rotate the cover left and right and guide the pan seal into the cavity using a small screwdriver. Oil the bolt threads and install two bolts to hold the cover in place. Install both dowel pins (chamfered end first), then install the remaining front cover bolts.
  16.  

The front cover-to-block bolts on the V6 diesel must be coated with an adhesive, GM part # 1052624 or equivalent to avoid coolant leaks and loss of bolt torque.

  1. Apply a lubricant, compatible with rubber, on the balancer seal surface.
  2.  
  3. Install the balancer and pulley. Torque the damper bolt to 271-420 ft. lbs. (367-569 Nm) for the V8 engine or to 160-350 ft. lbs. (217-474 Nm) on V6 engines.
  4.  
  5. Install the water pump fan and pulley.
  6.  
  7. Install the drive belts and adjust their tension.
  8.  
  9. Connect the radiator hoses.
  10.  
  11. Properly refill the engine cooling system.
  12.  

 
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