GM Service Manual Online
For 1990-2009 cars only

Use one of the following methods in order to locate a fluid oil leak.

Finding the Leak

  1. Determine if the fluid is one of the following types:
  2. • Engine oil
    • Automatic transmission fluid
    • Power steering fluid
  3. Use the following steps in order to determine the location of the fluid leak:
  4. 2.1. Run the vehicle at normal operating temperature.
    2.2. Park the vehicle over a large sheet of paper.
    2.3. After several minutes, observe the drops of fluid that fall on the paper.

    Use the drops on the paper in order to determine the location of the leak.

  5. Visually inspect around the suspected component.
  6. Inspect around the gasket mating surfaces for leaks.

    Use a mirror in order to find leaks in areas that are difficult to reach.

  7. If you cannot locate the leak, use one of the following items in order to clean the suspected area:
  8. • A degreaser
    • Steam
    • A spray solvent
  9. Thoroughly dry the area.
  10. Operate the vehicle for several miles at normal operating temperature and varying speeds.
  11. Visually inspect the suspected component.
  12. If you still cannot locate the leak, use the powder method or the black light and dye method in order to locate the leak.

Powder Method

Perform the following steps in order to diagnose the leak:

  1. Clean the suspected area.
  2. Apply an aerosol-type powder (such as foot powder) to the suspected area.
  3. Operate the vehicle under normal operating conditions.
  4. Visually inspect the suspected component.
  5. Trace the leak path over the white powder surface to the source.

Black Light and Dye Method

Tools Required

    • J 28428-E High Intensity Black Light
    • J 28431-6 Fluorescent Oil Additive

    Important: Follow the manufacturer's instructions that are included with the J 28431-6 .

  1. Pour the specified amount of J 28431-6 into the leaking component.
  2. Refer to the manufacturer's instructions for the proper amount of oil additive.

  3. Operate the vehicle under normal operating conditions.
  4. Shine the J 28428-E onto the suspected area.
  5. The J 28431-6 fluid will appear as a yellow path leading to the source of the oil leak.

Repairing the Leak

After you find the source of the leak, determine the cause of the leak. This action will enable you to properly repair the faulty component.

Gaskets

Inspect for a bent sealing flange. Repair the surface if the sealing flange is bent. A new gasket will not repair the leak.

Inspect for the following conditions before repairing a leak:

    • An incorrect fluid level
    • High pressure
    • Malfunctions in the crankcase ventilation system
    • Improperly tightened fasteners
    • Dirty or damaged threads on the fasteners
    • Warped flanges or sealing surfaces
    • Scratches, burrs or other damage to the sealing surface
    • A damaged or worn gasket
    • Cracking or porosity of the component
    • An improper sealant

Seals

Inspect for the following conditions before repairing a leak:

    • An incorrect fluid level
    • High pressure
    • Malfunctions in the crankcase ventilation system
    • Any of the following conditions on the seal bore:
       - Scratches
       - Burrs
       - Nicks
    • A damaged or worn seal
    • Improper installation
    • A cracked component
    • Inspect the shaft surface for the following conditions:
       - Scratches
       - Nicks
       - Damage
    • A loose or worn bearing