Jeep Wagoneer/Commando/Cherokee 1957-1983 Repair Information

Rear Main Oil Seal



See Figures 1 and 2

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Fig. Fig. 1: Installing the rear main seal packing 4 cyl-134 engine

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Fig. Fig. 2: Rear main seal installation 6 cyl-232, 258 and 8 cyl-304, 360 and 401 engines

  1. Remove the engine from the vehicle.
  3. Remove the timing chain cover and the crankshaft timing gear.
  5. Remove the oil pan, oil float support and the oil float.
  7. Slide the crankshaft thrust washer and all of the end-play adjusting shims off the front end of the crankshaft.
  9. Move the two pieces of the rear main bearing cap packing away from the side of the bearing cup and the cylinder block.
  11. You will now be able to see the marks on the bearing caps and the cylinder block for bearing number and position.
  13. Remove the screws and lockwashers that attach the main bearing caps to the cylinder block. Use a lifting bar beneath the ends of each bearing cap. Be careful not to exert too much pressure which could damage the cap or the dowels they fit onto. Lift each cap evenly on both sides until free of the dowels. If there is any reason to believe that any of the dowels have become bent during bearing cap removal, remove them and install new dowels. Remove the connecting rod caps and bearings.
  15. Remove the crankshaft.
  17. Remove the upper half of the rear main bearing oil seal from the cylinder block and the lower half from the oil seal groove in the rear main bearing cap.
  19. Install the main bearing caps and bearings on the cylinder block in their original positions.
  21. Reassemble the engine in reverse order of the above procedure.

It is possible to replace the rear main rubber seal without removing the crankshaft. The procedure is as follows:

  1. Loosen the crankshaft cap bolts and lower the crankshaft not more than 1 / 32 in. Remove the rear main bearing cap. Do not turn the crankshaft while it is loosened.
  3. Push the seal around the groove until it can be gripped and removed with a pair of pliers.
  5. Coat the new seal with clean engine oil and slide it into the groove until 3 / 8 in. protrudes from the groove. On American Motors engines push the seal around until its ends are flush with the block.
  7. Install the other half of the seal in the bearing cap with 3 / 8 in. protruding from the opposite side. This is so that the juncture of the two halves of the seal is not at the same point as the juncture of the bearing cap and the cylinder block. On American Motors engines, install the seal so that the ends are flush.
  9. Install the rear main bearing cap and tighten all the caps to the proper torque. Be sure that the caps have not fallen out of place and that they are tightened in a straight manner.