Chevrolet Blazer/Jimmy 1969-1982 Repair Guide

Rear Main Bearing Oil Seal

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REMOVAL & INSTALLATION



Gasoline Engine


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Fig. Fig. 1 Drive the upper half of the bearing seal out so that it may be grasped and removed with a pair of pliers



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Fig. Fig. 2 Fabricate an oil seal installation tool using the specifications illustrated



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Fig. Fig. 3 Sealing the bearing cap

Both halves of the rear main oil seal can be replaced without removing the crankshaft. Always replace the upper and lower seal together. The lip should face the front of the engine. Be very careful that you do not break the sealing bead in the channel on the outside portion of the seal while installing it. An installation tool can be fabricated to protect the seal bead.

  1. Remove the oil pan and rear main bearing cap.
  2.  
  3. Remove the oil seal from the bearing cap by prying it out with a small pry tool.
  4.  
  5. Remove the upper half of the seal with a small punch. Drive it around far enough to be gripped with pliers.
  6.  
  7. Clean the crankshaft and bearing cap.
  8.  
  9. Coat the lips and bead of the seal with light engine oil, keeping oil from the ends of the seal.
  10.  
  11. Position the fabricated tool between the crankshaft and seal seat.
  12.  
  13. Position the seal between the crankshaft and tip of the tool so that the seal bead contacts the tip of the tool. The oil seal lip should face forward.
  14.  
  15. Roll the seal around the crankshaft using the tool to protect the seal bead from the sharp corners of the crankcase.
  16.  
  17. The installation tool should be left installed until the seal is properly positioned with both ends flush with the block.
  18.  
  19. Remove the tool.
  20.  
  21. Install the other half of the seal in the bearing cap using the tool in the same manner as before. Light thumb pressure should install the seal.
  22.  
  23. Install the bearing cap with sealant applied to the mating areas of the cap and block. Keep sealant from the ends of the seal.
  24.  
  25. Tighten the rear main bearing cap to specifications.
  26.  
  27. Further installation is the reverse of removal.
  28.  

Diesel Engine
UPPER OIL SEAL

Tools have been released to provide a means of correcting upper seal leaks without the necessity of removing the crankshaft. The procedure of seal leak correction is detailed below.

  1. Drain the oil, remove the oil pan and then remove the rear main bearing cap.
  2.  
  3. Insert a packing tool against one end of the upper seal and drive the old seal gently into the groove until it is packed tight. This usually varies between 1 / 4 - 3 / 4 of an inch. Repeat the procedure on the other side.
  4.  
  5. Measure the amount the seal was driven up on one side and add 1 / 16 min. Cut this amount from the old seal removed from the main bearing cap. Repeat procedure for other side.
  6.  
  7. Place a drop of sealer on each end of the seal and cap.
  8.  
  9. Using two screwdrivers, work these two pieces of seal into the cylinder block. Use the packing tool and pack each piece up into the block.
  10.  
  11. Replace the lower seal and replace the cap.
  12.  
  13. Installation of the remaining components is in the reverse order.
  14.  

LOWER OIL SEAL
  1. Drain the oil and remove the oil pan and pump.
  2.  
  3. Remove the rear main bearing cap.
  4.  
  5. Remove the rear main bearing insert and oil seal.
  6.  
  7. Clean the bearing cap and seal grooves. Check for cracks.
  8.  

To install:

  1. Apply Loctite® 496 or the equivalent and install the seal into the cap by hand.
  2.  
  3. Use a seal installer and hammer the seal into the groove. To check if the seal is fully seated in the cap, slide the tool away from the seal. With the tool fully seated in the cap, slide the tool against the seal. If the tool butts against the seal, it must be driven further into the groove. If the undercut area of the tool slides over the seal, it's fully seated.
  4.  
  5. With the tool slightly rotated, cut the seal flush with the mating surface of the cap. Use a small screwdriver and pack the seal end fibers toward the center, away from the edges.
  6.  
  7. Clean and install the bearing insert.
  8.  
  9. Apply a thin film of anarobic sealant to the cap. Keep the sealant off the seal and bearing.
  10.  
  11. Just prior to assembly apply a light coating of oil to the crankshaft surface that will contact the seal.
  12.  
  13. Install the bearing cap and tighten to specifications.
  14.  
  15. Installation of the remaining components is in the reverse order.
  16.  

 
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