GM Astro/Safari 1985-1996 Repair Guide

Rear Main Oil Seal

Print

REMOVAL & INSTALLATION



2.5L Engine

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: The rear main seal should be installed using J-34924, or an equivalent installation tool-2.5L engine

The rear main oil seal is a one piece unit. It can be removed or installed without removing the oil pan or the crankshaft.

The following procedure requires the use of the GM Oil Seal Installation tool No. J-34924 or equivalent.

  1. Disconnect the negative battery cable for safety.
  2.  
  3. Remove the transmission. For details, please refer to the Transmission, Removal and Installation procedures in Drive Train .
  4.  
  5. If equipped with a manual transmission, remove the clutch assembly.
  6.  
  7. Matchmark and remove the flexplate or flywheel, as applicable.
  8.  
  9. Using a small prybar, carefully pry the oil seal from the rear of the crankshaft.
  10.  

When removing the oil seal, be careful not to damage the crankshaft sealing surface.

  1. To install the new oil seal into the rear retainer, perform the following procedures:
    1. Using fresh engine oil, lubricate the inner and outer diameter of the seal.
    2.  
    3. Install the new seal onto the seal installation tool No. J-34924 or equivalent, then position the tool assembly against the crankshaft.
    4.  
    5. Align the dowel with the alignment hole in the crankshaft and thread the attaching screws into the tapped holes in the crankshaft.
    6.  
    7. Using a screwdriver, tighten the screws securely; this will ensure that the seal is installed squarely over the crankshaft.
    8.  
    9. Turn the handle until it bottoms and remove the installation tool.
    10.  

  2.  
  3. Align and install the flywheel or flexplate (as applicable).
  4.  
  5. If equipped with a manual transmission, install the clutch assembly.
  6.  
  7. Install the transmission.
  8.  
  9. Connect the negative battery cable.
  10.  

4.3L Engine
1985 Models

See Figures 2, 3, 4 and 5



Click image to see an enlarged view

Fig. Fig. 2: Remove the lower half of the rear main seal from the main bearing cap-1985 4.3L engines



Click image to see an enlarged view

Fig. Fig. 3: Carefully drive the upper half of the seal from the engine block



Click image to see an enlarged view

Fig. Fig. 4: You can make a rear main seal installation tool using these dimensions



Click image to see an enlarged view

Fig. Fig. 5: Apply RTV sealant to the rear main cap-to-case mounting surface

The 1985 4.3L engines covered by this guide were originally equipped with a 2-piece rear main seal.

  1. Refer to the Oil Pan, Removal and Installation procedures in this section and remove the oil pan from the engine.
  2.  
  3. Remove the oil pump and the rear main bearing cap.
  4.  
  5. Pry the oil seal from the rear main bearing cap using a small suitable prytool.
  6.  
  7. Using a small hammer and a brass pin punch, CAREFULLY drive the top half of the oil seal from the rear main bearing. Drive it out far enough, so it may be removed with a pair of pliers.
  8.  
  9. Using a non-abrasive cleaner, clean the rear main bearing cap and the crankshaft.
  10.  

To install:
  1. Fabricate an oil seal installation tool from 0.004 in. (0.01mm) shim stock, shape the end to 1 / 2 in. (12.7mm) long by 11 / 64 in. (4.4mm) wide.
  2.  
  3. Coat the new oil seal with engine oil; DO NOT coat the mating ends of the seal.
  4.  
  5. Position the fabricated tool between the crankshaft and seal seat in the cylinder case.
  6.  
  7. Position the new half seal between the crankshaft and the tip of the tool, so that the seal bead contacts the tip of the tool.
  8.  

Make sure that the seal lip is positioned toward the front of the engine.

  1. Using the fabricated tool as a shoe horn, to protect the seal's bead from the sharp edge of the seal seat surface in the cylinder case, roll the seal around the crankshaft. When the seal's ends are flush with the engine block, remove the installation tool.
  2.  
  3. Using the same manner of installation, install the lower seal half onto the lower half of the rear main bearing cap.
  4.  
  5. Apply sealant to the cap-to-case mating surfaces and install the lower rear main bearing half to the engine; keep the sealant off of the seal's mating line.
  6.  
  7. Install the rear main bearing cap bolts and tighten to specification. Using a lead hammer, tap the crankshaft forward and rearward, to align the thrust bearing surfaces.
  8.  
  9. Install the oil pan.
  10.  
  11. Refill the crankcase with clean engine oil and connect the negative battery cable.
  12.  
  13. Start the engine, allow it to reach normal operating temperatures and check for leaks.
  14.  

1986-96 Models

See Figures 6, 7 and 8



Click image to see an enlarged view

Fig. Fig. 6: Exploded view of the rear main oil seal retainer mounting-4.3L engine (NOTE the retainer does NOT have to be removed in order to replace the seal)



Click image to see an enlarged view

Fig. Fig. 7: Carefully pry the seal from the retainer using a small prytool at the notches provided in the retainer



Click image to see an enlarged view

Fig. Fig. 8: A threaded seal installation tool such as J-35621 is necessary to properly seat the new seal

Unlike the 1985 4.3L engines covered by this guide (which were equipped with a 2-piece rear main seal), the 1986-96 4.3L engines utilize a 1-piece seal which is installed to a rear seal retainer that bolts to the back of the block.

The following procedure requires the use of the GM Oil Seal Installation tool No. J-35621 or equivalent.

  1. Disconnect the negative battery cable for safety.
  2.  
  3. Remove the transmission. For details, please refer to the Transmission, Removal and Installation procedures in Drive Train .
  4.  
  5. If equipped with a manual transmission, remove the clutch assembly.
  6.  
  7. Matchmark and remove the flexplate or flywheel, as applicable.
  8.  
  9. Insert a small prytool into the notches provided in the oil seal retainer and carefully pry the oil seal from the retainer.
  10.  

When removing the oil seal from the retainer, be careful not to nick the crankshaft sealing surface.

To install:
  1. Install the new oil seal into the rear retainer:
    1. Using engine oil, lubricate the inner and outer diameter of the seal.
    2.  
    3. Install a new oil seal onto the GM Oil Seal Installation tool No. J-35621 (or equivalent), then position the tool and seal assembly against the crankshaft and thread the attaching screws into the tapped holes in the crankshaft.
    4.  
    5. Using a screwdriver, tighten the screws securely; this will ensure that the seal is installed squarely over the crankshaft.
    6.  
    7. Turn the handle until it bottoms and remove the installation tool.
    8.  

  2.  
  3. Align and install the flywheel or flexplate (as applicable).
  4.  
  5. If equipped with a manual transmission, install the clutch assembly.
  6.  
  7. Install the transmission.
  8.  
  9. Connect the negative battery cable.
  10.  

 
label.common.footer.alt.autozoneLogo