GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Rear Main Seal

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REMOVAL & INSTALLATION



See Figures 1, 2, 3 and 4

Except One Piece Seal
  1. Remove the oil pan. Remove the oil pump where required. Remove the main bearing cap.
  2.  
  3. Pry the lower seal out of the bearing cap with a suitable tool, being careful not to gouge the cap surface.
  4.  
  5. Remove the upper seal by lightly tapping on the one end with a brass pin punch until the other end can be grasped and pulled out.
  6.  
  7. Clean the bearing cap, cylinder block and crankshaft mating surfaces with solvent. Inspect these surfaces for gouges, nicks and burrs.
  8.  
  9. Apply a light coat of engine oil on the seal lips and bead, but keep the seal ends clean.
  10.  
  11. Insert the tip of the installation tool between the crankshaft and the seal in the cylinder block. Place the seal between the crankshaft and the seal of the cylinder block. Place the seal between the tip of the tool and the crankshaft, so that the bead contacts the tip of the tool.
  12.  

Do not remove the tool until the opposite end of the seal is flush with the cylinder block surface.

  1. Remove the installation tool, being careful not to pull the seal out at the same time.
  2.  
  3. Using the same procedure, install the lower seal into the bearing cap. Use your finger and thumb or a wooden hammer handle to level the seal into the cap.
  4.  
  5. Apply sealer to the cylinder block only where the cap mates to the surface. Do not apply sealer to the seal ends.
  6.  
  7. Install the rear cap and torque to specification.
  8.  
  9. Install the oil pump and oil pan.
  10.  



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Fig. Fig. 1: Installing the lower main bearing oil seal



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Fig. Fig. 2: Cutting off the lower seal ends

One Piece Seal
  1. Remove the transmission from the vehicle.
  2.  
  3. Using the notches provided in the rear seal retainer, pry out the seal using the proper tool.
  4.  

Care should be taken when removing the seal so as not to nick the crankshaft sealing surface.

  1. Before installation lubricate the inside and outside diameter of the new seal with clean engine oil.
  2.  
  3. Install the seal on tool J-3561 or equivalent. Thread the tool into the rear of the crankshaft. Tighten the screws snugly, this is to insure that the seal will be installed squarely over the crankshaft. Tighten the tool wing nut until it bottoms.
  4.  
  5. Remove the tool from the crankshaft.
  6.  
  7. Install the transmission.
  8.  



Click image to see an enlarged view

Fig. Fig. 3: One piece seal removal notches



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Fig. Fig. 4: Installing the one piece seal

One Piece Seal Retainer and Gasket
  1. Remove the transmission from the vehicle.
  2.  
  3. Remove the oil pan.
  4.  
  5. Remove the retainer and seal assembly.
  6.  
  7. Remove the gasket.
  8.  

Whenever the retainer is removed a new retainer gasket and rear main seal must be installed.

  1. Installation is the reverse of removal. Once the oil pan has been installed, the rear main seal may be installed.
  2.  

 
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