Crankshaft Rear Main Oil Seal Leaks in Some 60-degree V6 GM Engines - Engine Builder Magazine

Crankshaft Rear Main Oil Seal Leaks in Some 60-degree V6 GM Engines

This information only applies to 60 degree V6 engines. It is important to verify that the following information is correct before continuing:

Models: 1986-2006 GM cars and light-duty trucks (including Saturn) with 2.8L, 3.1L, 3.4L, 3.5L, 3.9L 60 degree V6 engines (VINs D, E, F, J, K, L, M, N, R, S, T, V, W, X, Z, 1, 8, 9 – RPOs LG6, LA1, LNJ, or LN9, LG8, LL1 or LX9, L82, LL2, LB8, LH0, LG5, LB6, LE2 or LQ1, LH7, LC1, LX9, L44, LZ4, LZE, LZ9)

• Year of vehicle

• V6 engine size

• VIN code


This information only applies to above listed engines. If one or more items do not match the above list, then this information does not apply.

Note: This information does not apply to 2004-2005 Saturn VUE models with 3.5L DOHC V6 engine or 2005-2006 Cadillac CTS with 2.8L HFV6 engine (VIN T – RPO LP1).

Some engine customers may complain about external oil leaks on these engines. Before replacing the new design rear main oil seal, be sure the PCV system is operating correctly.

The new seal described below coes with a protective nylon sleeve already installed in the seal. This sleeve assures that the seal is installed in the correct direction and also protects the seal from getting damaged during installation. Do not remove the protective sleeve from the seal; if removed, the installation tool (EN-48108) will not work.

A new design crankshaft rear main oil seal and installation tool (EN-48108) has been released. This seal incorporates features that improve high mileage durability. Replace the crankshaft rear main oil seal with the new design rear main oil seal, p/n 12592195 (Canadian p/n 31022784) using the following procedures.

The rear main oil seal installation tool (EN-48108) has a unique design to allow the technician to easily install the rear main seal squarely in the correct depth and direction. Before proceeding with installation, review the above illustration to become familiar with the following components:

  • Mandrel
  • Drive Drum
  • Drive Nut
  • Washer
  • Bearing

Removal Procedure

Remove the crankshaft rear main oil seal using one of the following techniques:

  • Refer to figure 2 illustration for removing new style crankshaft rear main oil seal.
  • The seal lip faces outward. Insert a flat-bladed or similar tool between the sealing lip and outer casting of the seal at an angle.
  • Pry seal out by moving  tool towards the center of crankshaft.
  • Refer to figure 3 illustration for removing old style crankshaft rear main oil seal.

    Seal lip faces inward. Insert a flat-bladed or similar tool between the outer seal casing and the engine block casting.

  • Gently pry seal out (refer to figure 3).
  • Repeat the above steps as necessary, around the crankshaft rear oil seal, until the seal is removed.

Installation Procedure

Do not remove the protective nylon sleeve from the new rear main seal prior to installation. The EN-48108 is designed to install the rear main seal with the protective sleeve in place. Never apply or use any oil, lubricants or sealing compounds on the crankshaft rear main oil seal.

  1. Clean the crankshaft sealing surface with a clean, lint-free towel. Inspect the lead-in edge of the crankshaft for burrs or sharp edges with corcus cloth or equivalent before proceeding.
  2. Align the mandrel dowel pin to the dowel pin hole in the crankshaft (figure 4).
  3. Using a large flat blad screwdriver, tighten the two mandrel screws to the crankshaft. Ensure the mandrel is snug to the crankshaft hub (figure 5).
  4. Install the rear main seal (1), with the protective nylon sleeve attatched (2) onto the mandrel. The seal, if properly installed, will center on a step that protrudes from the center of the mandrel. As and error proof, seal will fit only one way onto the mandrel (figure 6).
  5. Install the outer drive drumonto the mandrel (EN-48108). Install the bearing,washer and the drive nut onto the threaded shaft (figure 7).
  6. Using a wrench, turn the drive nut on the mandrel, which will push the seal into the engine bore. Turn the wrench until the drive drum is snug and flush against the engine block (figure 8).
  7. Loosen and remove drive nut, washer, bearing and drive drum. Discard protective nylon sleeve.

    Verify that the seal has seated properly.

  8. Use a flat blade screwdriver to remove the two attachment screws from the mandrel and remove mandrel from crankshaft hub (figure 9).


Parts Information

Part Number                 Description

12592195 (U.S.)           Seal assembly, crankshaft rear main oil (includes nylon protective sleeve)

31022784 (Canada)     Seal kit, crankshaft rear main oil (includes nylon protective sleeve)figure 1figure 2figure 3figure 4figure 5figure 6figure 7figure 8Figure 9


Some or all of the preceding technical information was provided by the
Automotive Parts Remanufacturers Association (APRA). For more
information on technical bulletins available through APRA call
703-968-2772 or visit

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