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Davo
Davo, Master technician
Category: Chevy
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Experience:  ASE Master Technician also L1 Advanced Engine Performance Specialist
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1987 chevy: 350 small block, does the seal slide over the main..crank

Customer Question

how do u install the one piece rear seal in a 1987 chevy 350 small block, does the seal slide over the main to the inside of the crank and the other piece on the out side?
Submitted: 10 years ago.
Category: Chevy
Expert:  Davo replied 10 years ago.

1986-96 vehicles

See Figures 5, 6 and 7

  1. Disconnect the negative battery cable.

  2. Remove the transmission assembly.

  3. For manual transmission vehicles, remove the clutch cover and disc assembly.

  4. Remove the flywheel bolts and remove the flywheel from the vehicle.

  5. Using the notches provided in the seal retainer and a small suitable tool, pry the old seal from the engine. Be careful not to nick the crankshaft sealing surface when removing the seal.

Click image to see an enlarged view
Fig. 5: Rear main seal removal-1986-91 vehicles, except 5.7L (VIN J) engine


To install:

Click image to see an enlarged view
Fig. 6: Exploded view of the rear main seal and related components


  1. Lubricate the inside and outside of a new seal with clean engine oil.

  2. Install the seal on tool J-35621 or equivalent rear main seal installer.

Click image to see an enlarged view
Fig. 7: Use the proper tool to install the rear main seal


  1. Thread the screws of the tool into the rear of the crankshaft and tighten the screws snugly to assure proper seal alignment and installation.

  2. Tighten the tool wingnut until it bottoms and then remove the tool.

  3. Install the flywheel and tighten the bolts to 74 ft. lbs. (100 Nm).

  4. If equipped, install the clutch cover and disc assembly.

  5. Install the transmission assembly.

  6. Lower the vehicle and connect the negative battery cable.


5.7L (VIN J) Engine

See Figure 8

  1. Disconnect the negative battery cable.

  2. Remove transmission assembly.

  3. Remove the clutch cover and disc assembly.

  4. Remove the flywheel bolts and flywheel.

  5. Remove the screws attaching the crankshaft rear main oil seal/housing assembly to the cylinder case.

  6. Remove the retaining screws, then remove the seal/housing assembly from the engine.

  7. Remove the seal from the housing.

Click image to see an enlarged view
Fig. 8: Location of the crankshaft rear main seal-5.7L (VIN J) engine


To install:

  1. Lubricate the seal lip with engine oil.

  2. Install seal into housing using crankshaft rear seal tool J-37312 or equivalent. Make sure the seal is installed 1.0-1.5mm below the housing surface.

  3. Install the housing and tighten the bolts to 89 inch lbs. (10 Nm).

  4. Apply Loctite® 242 or equivalent, to the bolts threads, then install the flywheel and tighten the bolts to 74 ft. lbs. (100 Nm).

  5. Install the clutch cover and disc assembly.

  6. Install the transmission assembly.

  7. Connect the negative battery cable.

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