GM Service Manual Online
For 1990-2009 cars only

Most fluid oil leaks are easily located and repaired by visually finding the leak and replacing or repairing the necessary parts. On some occasions a fluid leak may be difficult to locate or repair.

Use the following steps in order to find the leak:

Finding the Leak

  1. Identify the fluid, determine whether it is engine oil, automatic transmission fluid or power steering fluid etc.
  2. From what point is the fluid leaking? After running the vehicle at normal operating temperature, park the vehicle over a large sheet of paper. After a few minutes, one should be able to find the approximate location of the leak by the drippings on the paper.
  3. Visually check around the suspected component. Check around the gasket mating surfaces for leaks. A mirror is useful for finding leaks in areas that are hard to reach.
  4. If the leak still cannot be found, it may be necessary to clean the suspected area with a degreaser, steam or spray solvent. Clean the area well, then thoroughly dry the area. Operate the vehicle for several miles at normal operating temperature and varying speeds After operating the vehicle, visually check the suspected component. If the leak still cannot be located, try using the powder or black light and dye method.

Powder Method

Perform the following steps in order to perform the powder method:

  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. The leak path over the white powder surface to the source should be able to be traced.

Black Light and Dye Method

    • J 28428-E High Intensity Black Light or equivalent
    • J 28431-6 Fluorescent Oil Dye - 6 1 - oz

Oil leaks may be found using the J 28428-E and the J 28431-6 . For best results follow the manufacturer's instructions 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 dye.

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

Repairing the Leak

Once the origin of the leak has been pinpointed and traced back to its source, the cause of the leak must be determined in order for it to be repaired properly. If a gasket is replaced, but the sealing flange is bent, the new gasket will not repair the leak. The surface must be repaired also. Before attempting to repair a leak, ensure that the following conditions exist:

Gaskets

  1. Inspect for a fluid level that is too high.
  2. Inspect for pressure that is too high.
  3. Inspect the crankcase ventilation system for malfunctions.
  4. Inspect for improperly tightened fasteners or dirty/damaged threads.
  5. Inspect for warped flanges or sealing surfaces.
  6. Inspect for scratches, burrs or other damage to the sealing surface.
  7. Inspect for a damaged or worn gasket.
  8. Inspect for cracking or porosity of the component
  9. Inspect for use of an improper sealant (where applicable).

Seals

  1. Inspect for a fluid level that is too high.
  2. Inspect for pressure that is too high.
  3. Inspect the crankcase ventilation system for malfunctions.
  4. Inspect for a damaged seal bore (scratched, burred or nicked).
  5. Inspect for a damaged or worn seal.
  6. Inspect for improper installation.
  7. Inspect the component for cracks.
  8. Inspect the shaft surface for scratches, nicks or damage.
  9. Inspect for a loose or worn bearing, causing excessive seal wear.