GM S-Series Pick-ups and SUV's 1994-1999 Repair Guide

Rear Main Oil Seal

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Replacing a rear main seal is a formidable task. Before replacing the seal, care should be taken in determining the exact source of the leak. Various manufacturers produce a fluorescent die oil additive which can be added to your crankcase. The engine is run, allowing the dyed oil to leak from the same source, then a black light is used to illuminate the leak so it can be traced.

REPLACEMENT



2.2L Engines

See Figures 1, 2, 3 and 4



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Fig. Fig. 1: View of the rear main seal-2.2L engines



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Fig. Fig. 2: Prying out the rear main seal-2.2L engines



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Fig. Fig. 3: Installing the rear main seal



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Fig. Fig. 4: The rear main seal may be installed using a suitable seal driver tool and a hammer

The following procedure requires the use of a seal installation tool such as J-34686 or equivalent.

  1. Remove the transmission assembly.
  2.  
  3. If equipped, remove the clutch.
  4.  
  5. Remove the flywheel and verify the rear main seal is leaking.
  6.  
  7. Remove the seal by inserting a small prybar through the dust lip at an angle and prying the seal out. Be careful not to score the crankshaft sealing surface.
  8.  

To install:
  1. Check the crankshaft and seal bore for nicks or damage. Repair as necessary.
  2.  
  3. Lightly coat the inner diameter of the seal with clean engine oil.
  4.  
  5. Position the seal over the mandrel of the J-34686 or an equivalent installation tool. Make sure the dust lip (back of seal) is bottomed squarely against the collar of the tool.
  6.  
  7. Lightly coat the outer diameter of the seal using clean engine oil, then position the tool to the crankshaft while aligning the tool dowel pin with the crankshaft dowel pin hole. Tighten the screws to attach the tool and assure proper seal installation.
  8.  
  9. Turn the handle of the tool until the collar is tight against the case and the seal has been completely seated.
  10.  
  11. Turn the handle of the tool out until it stops, then remove the tool and verify that the seal is seated squarely in the bore.
  12.  
  13. Install the flywheel.
  14.  
  15. If equipped, install the clutch.
  16.  
  17. Install the transmission assembly.
  18.  

4.3L Engine

See Figure 5



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Fig. Fig. 5: Installing the rear oil seal using seal installation tool J-35621

The following procedure requires the use of a seal installation tool (such as J-35621) or equivalent.

  1. Remove the transmission assembly.
  2.  
  3. If equipped, remove the clutch assembly.
  4.  
  5. Remove the flywheel and verify the rear main seal is leaking.
  6.  
  7. Remove the seal by inserting a small prybar into the notches provided in the seal retainer and pry the seal out. Be careful not to score the crankshaft sealing surface.
  8.  

To install:
  1. Check the crankshaft and seal bore for nicks or damage. Repair as necessary.
  2.  
  3. Lightly coat the inner and outer diameters of the seal with clean engine oil, then position the seal on the installation tool.
  4.  
  5. Position the tool to the crankshaft and thread the tool's screws into the tapped holes. Tighten the screws securely using a screwdriver to attach the tool and assure proper seal installation.
  6.  
  7. Turn the handle of the tool until it bottoms and the seal has been completely seated.
  8.  
  9. Turn the handle of the tool out until it stops, then remove the tool and verify that the seal is seated squarely in the bore.
  10.  
  11. Install the flywheel to the engine.
  12.  
  13. If equipped, install the clutch assembly.
  14.  
  15. Install the transmission assembly.
  16.  

 
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