Repair Pontiac Mid-size 1974-1983 Repair Guide

Timing Chain Cover and Front Oil Seal

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REMOVAL & INSTALLATION



151 Four and 250 Inline Six Cylinder Engines


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Fig. Fig. 1 Apply sealer to the front cover mounting points as shown-151 4-cylinder and 250 inline 6-cylinder engines



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Fig. Fig. 2 Cut the oil pan seal flush with the front of the block



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Fig. Fig. 3 You must modify the oil pan front seal by cutting the tabs off, as shown

  1. Drain the engine coolant, remove the radiator hoses, and remove the radiator.
  2.  
  3. Remove the fan belt and any accessory belts. Remove the fan pulley.
  4.  
  5. A harmonic balancer puller is necessary to pull the balancer. Install the puller and remove the balancer.
  6.  
  7. Remove the two screws which attach the oil pan to the front cover. Remove the screws which attach the front cover to the block. Do not remove the cover yet.
  8.  
  9. Before the front cover is removed, it is necessary to cut the oil pan front seal. Pull the cover forward slightly.
  10.  
  11. Using a sharp knife or razor knife, cut the oil pan front seal flush with the cylinder block on both sides of the cover.
  12.  
  13. Remove the front cover and the attached portion of oil pan front seal. Remove the front cover gasket from the block.
  14.  

To install:

  1. Obtain an oil pan front seal. Cut the tabs from the new seal.
  2.  
  3. Install the seal in the front cover, pressing the tips into the holes provided in the cover. Coat the mating area of the front cover with a Room Temperature Vulcanizing (RTV) sealer first.
  4.  
  5. Coat the new front cover gasket with sealer and install it on the cover.
  6.  
  7. Apply a 1 / 8 in. bead of RTV sealer to the joint formed at the oil pan and cylinder block.
  8.  
  9. Install the front cover.
  10.  
  11. Install the harmonic balancer. Make sure the front cover seal is positioned evenly around the balancer. If you do not have access to a balancer installation tool (and you probably don't), you can either fabricate one using the illustration as a guide, or you can tap the balancer on using a brass or plastic mallet. If you use the last method, make sure the balancer goes on evenly.
  12.  
  13. The rest of the installation is in the reverse order of removal.
  14.  

V6 and V8 Engines


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Fig. Fig. 4 Exploded view of the engine front cover mounting-all V6 and V8 engines are similar



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Fig. Fig. 5 To remove the timing chain cover, unfasten the pulley retaining bolts ...



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Fig. Fig. 6 ... then remove the pulley



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Fig. Fig. 7 Remove the harmonic balancer bolt and washer



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Fig. Fig. 8 Attach a suitable puller to the harmonic balancer ...



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Fig. Fig. 9 ... then remove the harmonic balancer from the crankshaft



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Fig. Fig. 10 Some pullers secure the crankshaft to prevent it from turning



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Fig. Fig. 11 Unfasten the lower timing chain cover retaining bolts



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Fig. Fig. 12 Remove the upper timing chain cover retaining bolts ...



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Fig. Fig. 13 ... then remove the timing chain front cover from the engine



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Fig. Fig. 14 Install a new front cover seal using a seal installation tool and a rubber mallet



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Fig. Fig. 15 Carefully trim the pan seal using a razor blade



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Fig. Fig. 16 Sealer application points-Chevrolet and Oldsmobile built engines



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Fig. Fig. 17 Guiding the engine front cover into place



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Fig. Fig. 18 On 1977 and later Olds engines, grind a chamfer on the each dowel pin

BUICK ENGINES
  1. Drain the cooling system.
  2.  
  3. Remove the radiator, fan, pulley and belt.
  4.  
  5. Remove the fuel pump and alternator, if necessary to remove cover.
  6.  
  7. Remove the distributor. If the timing chain and sprockets will not be disturbed, note the position of the distributor for installation in the same position.
  8.  
  9. Remove the thermostat bypass hose.
  10.  
  11. Remove the harmonic balancer.
  12.  
  13. Remove the timing chain-to-crankcase bolts.
  14.  
  15. Remove the oil pan-to-timing chain cover bolts and remove the timing chain cover.
  16.  
  17. Using a punch, drive out the old seal and the shedder toward the rear of the seal.
  18.  
  19. Coil the new packing around the opening so the ends are at the top. Drive in the shedder using a punch. Properly size the packing by rotating a hammer handle around the packing until the balancer hub can be inserted through the opening.
  20.  

PONTIAC ENGINES
  1. Drain the radiator and the cylinder block.
  2.  
  3. Loosen the alternator adjusting bolts.
  4.  
  5. Remove the fan, fan pulley, accessory drive belts, and water pump.
  6.  
  7. Disconnect the radiator hoses.
  8.  
  9. Remove the fuel pump.
  10.  
  11. Remove the harmonic balancer bolt and washer.
  12.  
  13. Remove harmonic balancer.
  14.  

Do not pry on rubber-mounted balancers. If only the seal is to be replaced, proceed to Step 12.

  1. Remove the front four oil pan to timing cover bolts.
  2.  
  3. Remove the timing cover bolts and nuts and cover to intake manifold bolt.
  4.  
  5. Pull the cover forward and remove.
  6.  
  7. Remove the O-ring from the recess in the intake manifold, then clean all the gasket surfaces.
  8.  
  9. To replace the seal, pry it out of the cover using a suitable prytool. Install the new seal with the lip inward.
  10.  

The seal can be replaced with the cover installed.

  1. To install, reverse the removal procedure, making sure all gaskets are replaced. Tighten the four oil pan bolts to 12 ft. lbs., and the fan pulley bolts to 20 ft. lbs.
  2.  

OLDSMOBILE GASOLINE ENGINES
  1. Drain the coolant. Disconnect the radiator hose and the bypass hose. Remove the fan, belts and pulley.
  2.  
  3. Remove the vibration damper and crankshaft pulley.
  4.  
  5. Drain the oil and remove the oil pan.
  6.  
  7. Remove the front cover attaching bolts and remove the cover, timing indicator and water pump from the front of the engine.
  8.  
  9. On 1977 and later models, grind a chamfer on the end of each dowel pin as illustrated. When installing the dowel pins, they must be inserted chamfered end first. Trim about 1 / 8 " from each end of the new front pan seal and trim any excess material from the front edge of the oil pan gasket. Be sure all mating surfaces are clean.
  10.  
  11. Install in the reverse order of removal using a new gasket with sealing compound. Tighten self-tapping water pump attaching screws to 13 ft. lbs., 5 / 16 in. front cover attaching bolts to 25 ft. lbs. and the four bottom bolts (cover plate) to 35 ft. lbs. Tighten the pulley hub bolt to 310 ft. lbs.
  12.  

CHEVROLET ENGINES
  1. Drain the cooling system.
  2.  
  3. Remove the crankshaft pulley. Remove the water pump. Remove the screws holding the timing case cover to the block and remove the cover and gaskets.
  4.  
  5. Use a suitable tool to pry the old seal out of the front face of the cover.
  6.  
  7. Install the new seal so that open end is toward the inside of the cover.
  8.  

Coat the lip of the new seal with oil prior to installation.

  1. Check that the timing chain oil slinger is in place against the crankshaft sprocket.
  2.  
  3. Install the cover carefully onto the locating dowels.
  4.  
  5. Tighten the attaching screws to 6-8 ft. lbs.
  6.  

DIESEL ENGINE
  1. Drain the cooling system and disconnect the radiator hoses.
  2.  
  3. Remove all belts, fan and pulley, crankshaft pulley and balancer, using a balancer puller.
  4.  


CAUTION
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° 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 and water pump.
  2.  
  3. It may be necessary to grind a flat on the cover for gripping purposes.
  4.  
  5. Grind a chamfer on one end of each dowel pin.
  6.  
  7. Cut the excess material from the front end of the oil pan gasket on each side of the block.
  8.  
  9. Clean the block, oil pan and front cover mating surfaces with solvent.
  10.  
  11. Trim about 1 / 8 in. off each end of a new front pan seal.
  12.  
  13. Install a new front cover gasket on the block and a new seal in the front cover.
  14.  
  15. Apply sealer to the gasket around the coolant holes.
  16.  
  17. Apply sealer to the block at the junction of the pan and front cover.
  18.  
  19. 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.
  20.  
  21. Apply a lubricant, compatible with rubber, on the balancer seal surface.
  22.  
  23. Install the balancer and bolt. Tighten the bolt to 200-300 ft. lbs.
  24.  
  25. Install the other parts in the reverse order of removal.
  26.  

 
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