AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

Rear Main Bearing Oil Seal

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REMOVAL & INSTALLATION 4-121 Engine



See Figure 1

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Fig. Fig. 1: Common rear main oil seal assembly4-121 engine

The rear main bearing oil seal consists of a single piece of formed neoprene with a single lip. To replace the seal, proceed as follows.

  1. Remove the transmission assembly. If manual transmission, remove the pressure plate and flywheel.
  2.  
  3. Remove the crankshaft seal from its seat in the block, while exercising care not to scratch the seal contacting area of the crankshaft.
  4.  

To install:
  1. Install the seal, after lubricating the lip with engine oil, into the recess of the block, until the seal bottoms. The seal should be about 1 / 32 in. (0.79mm) below the surface of the block.
  2.  
  3. Install the flywheel and components. Install the transmission assembly, adjust as necessary, start the engine and check for oil leakage.
  4.  

4-150 Engine See Figure 2

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Fig. Fig. 2: Location of the rear main seal4-151 engines

  1. Remove the transmission.
  2.  
  3. Remove the flywheel.
  4.  
  5. Pry out the seal from around the crankshaft flange.
  6.  

To install:
  1. Coat the inner lip of the new seal with clean engine oil.
  2.  
  3. Gently tap the new seal into place, flush with the block, using a rubber or plastic mallet.
  4.  
  5. Install the flywheel.
  6.  
  7. Install the transmission.
  8.  

4-151 Engine See Figure 3

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Fig. Fig. 3: Use a prytool to remove the rear main seal from the crankshaft4-151 engine

The seal is a one-piece unit that can be removed and installed without removing the oil pan or crankshaft.

  1. Raise and support the vehicle on jackstands.
  2.  
  3. Remove the transmission and transfer case as an assembly.
  4.  
  5. Disconnect and remove the starter.
  6.  
  7. On manual transmission vehicles, remove the flywheel inspection plate, and clutch slave cylinder.
  8.  
  9. Remove the flywheel or drive plate housing.
  10.  
  11. On manual transmission, remove the clutch assembly by backing out the bolts evenly around the pressure plate.
  12.  
  13. Remove the flywheel or drive plate. It is a good idea to match mark the flywheel location for assembly.
  14.  
  15. Using a small bladed screwdriver, pry the rear seal out from around the crankshaft hub. Be careful to avoid damaging the sealing groove or hub.
  16.  

To install:
  1. With a light hammer, tap the seal into position with the lip facing the front of the engine.
  2.  
  3. Install the flywheel or drive plate.
  4.  
  5. On manual transmission, install the clutch assembly by tightening the bolts evenly around the pressure plate.
  6.  
  7. Install the flywheel or drive plate housing.
  8.  
  9. On manual transmission vehicles, install the flywheel inspection plate, and clutch slave cylinder.
  10.  
  11. Install the starter.
  12.  
  13. Install the transmission and transfer case as an assembly.
  14.  

6- and 8-Cylinder Engines See Figure 4

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Fig. Fig. 4: Coat the ends of the seal with RTV, the curved surface with soap and lip with engine oil

This seal is a two piece neoprene type with a single lip.

  1. Raise and support the vehicle on jackstands.
  2.  
  3. Remove the oil pan.
  4.  
  5. Remove the rear main bearing cap and discard the lower seal.
  6.  
  7. Loosen all remaining main bearing caps.
  8.  
  9. Using a center punch, carefully drive the upper half of the seal out of the block just far enough to graph with a pliers and pull out.
  10.  
  11. Remove the oil pan front and rear seals and the side gaskets.
  12.  

To install:
  1. Clean all gasket surfaces.
  2.  
  3. Wipe clean the sealing surface of the crankshaft and coat it lightly with engine oil.
  4.  
  5. Coat the lip of the upper seal with engine oil and install it in the block. The lip faces forward.
  6.  
  7. Coat both end tabs of the lower seal with RTV silicone sealer. Do not get any RTV sealer on the seal lip.
  8.  
  9. Coat the outer curved surface of the seal with liquid soap. Coat the seal lip with engine oil.
  10.  
  11. Install the seal into the cap, pressing firmly.
  12.  
  13. Coat both chamferred edges of the cap with RTV sealer.
  14.  


WARNING
Do not allow any RTV sealer to get on the mating surfaces of the cap or block as this will affect bearing clearance.

  1. Install the rear main cap.
  2.  
  3. Tighten all main bearing cap bolts gradually to 80 ft.lb.
  4.  
  5. Replace the oil pan.
  6.  

 
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