GM Full Size Vans 1967-1986 Repair Guide

Timing Chain Cover and Front Oil Seal

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REMOVAL & INSTALLATION



Inline Six Cylinder Engine

See Figures 1 and 2



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Fig. Fig. 1: Applying sealer to the front cover on the 250 inline six engine



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

  1. Drain the engine coolant, remove the radiator hoses, and remove the radiator.
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CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by 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 belt and any accessory belts. Remove the fan pulley.
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  3. A harmonic balancer puller is necessary to pull the balancer. Install the puller and remove the balancer.
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  5. 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.
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  7. Before the front cover is removed, it is necessary to cut the oil fan front seal. Pull the cover forward slightly.
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  9. Using a sharp knife or razor knife, cut the oil pan front seal flush with the cylinder block on both sides of the cover.
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  11. Remove the front cover and the attached portion of oil pan seal. Remove the front cover gasket from the block.
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  13. Install the front cover, first obtain an oil pan front seal. Cut the tabs from the new seal.
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  15. 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.
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  17. Coat the new front cover gasket with sealer and install it on the cover.
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  19. Apply a 1 / 8 in. (3mm) bead of RTV sealer to the joint formed at the oil pan and cylinder block.
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  21. Install the front cover.
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  23. Install the harmonic balancer. Make sure the front cover seal is positioned evenly around the balancer. If you so 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.
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  25. The rest of the installation is in the reverse order of removal.
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Gasoline V6 and V8 Engines

See Figures 3 through 9



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Fig. Fig. 3: Remove the timing cover bolts



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Fig. Fig. 4: Use a prytool to separate the cover from the engine



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Fig. Fig. 5: Remove the cover from the engine



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Fig. Fig. 6: Exploded view of the water pump, front cover and related components-gasoline V8 engines



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Fig. Fig. 7: View of the seal installation with the seal removed



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Fig. Fig. 8: View of the seal installation with the cover installed



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Fig. Fig. 9: View of the sealer application-gasoline V8 engines

  1. Drain the cooling system.
  2.  

  1. Remove the crankshaft pulley and damper. Remove the water pump. Remove the screws holding the timing case cover to the block and remove the cover and gaskets.
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  3. Use a suitable tool to pry the old seal out of the front face of the cover.
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  5. Install the new seal so that the open end is toward the inside of the cover.
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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.
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  3. Apply sealer to the front cover as shown in the accompanying illustration. Install the cover carefully onto the locating dowels.
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  5. Tighten the attaching screws to 6-8 ft. lbs. (8-10 Nm).
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Diesel Engine

See Figures 10 and 11



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Fig. Fig. 10: Exploded view of the front cover assembly showing sealer application-6.2L diesel engines



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Fig. Fig. 11: Injection pump and cam gear alignment-6.2L diesel engines

  1. Drain the cooling system.
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  1. Remove the water pump.
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  3. Rotate the crankshaft to align the marks on the injection pump driven gear and the camshaft gear as shown in the illustration.
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  5. Scribe a mark aligning the injection pump flange and the front cover.
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  7. Remove the crankshaft pulley and torsional damper.
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  9. Remove the front cover-to-oil pan bolts (4).
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  11. Remove the two fuel return line clips.
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  13. Remove the injection pump retaining nuts from the front cover.
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  15. Remove the baffle. Remove the remaining cover bolts, and remove the front cover.
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  17. If the front cover oil seal is to be replaced, it can now be pried out of the cover with a suitable prying tool. Press the new seal into the cover evenly.
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The oil seal can also be replaced with the front cover installed. Remove the torsional damper first, then pry the old seal out of the cover using a suitable prying tool. Use care not to damage the surface of the crankshaft. Install the new seal evenly into the cover and install the damper.

  1. To install the front cover, first clean both sealing surfaces until all traces of old sealer are gone. Apply a 0.07 in. (2mm) bead of sealant (GM sealant #1052357 or equivalent) to the sealing surface as shown in the illustration. Apply a bead of RTV type sealer to the bottom portion of the front cover which attached to the oil pan. Install the front cover.
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  3. Install the baffle.
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  5. Install the injection pump, making sure the scribe marks on the pump and front cover are aligned.
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  7. Install the injection pump driven gear, making sure the marks on the cam gear and pump are aligned. Be sure the dowel pin and the three holes on the pump flange are also aligned.
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  9. Install the fuel line clips, the front cover-to-oil bolts, and the torsional damper and crankshaft pulley. Torque the pan bolts to 4-7 ft. lbs. (5-9 Nm), and the damper bolt to 140-162 ft. lbs. (189-219 Nm).
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