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. The following procedures may help you in locating and repairing most leaks.

Finding the Leak

  1. Identify the fluid. Determine whether it is engine oil, automatic transmission fluid, power steering fluid, etc.
  2. Identify where the fluid is leaking from.
  3. 2.1. After running the vehicle at normal operating temperatures, park the vehicle over a large sheet of paper.
    2.2. Wait a few minutes.
    2.3. You should be able to find the approximate location of the leak by the drippings on the paper.
  4. Visually inspect around the suspected component. Inspect around all the gasket mating surfaces for leaks. A mirror is useful for finding leaks in areas that are hard to reach.
  5. If the leak still cannot be found, it may be necessary to clean the suspected area with a degreaser, steam, or spray solvent.
  6. 4.1. Clean the area well.
    4.2. Dry the area.
    4.3. Operate the vehicle for several miles at normal operating temperature and varying speeds.
    4.4. After operating the vehicle, visually inspect the suspected component.
    4.5. If the leak is not located, try using the powder or black light and dye method.

Powder Method

  1. Clean the suspected area.
  2. Apply the 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. You should be able to trace the leak path over the white powder surface to the source.

Black Light and Dye Method

A dye and light kit is available for finding leaks. Refer to the manufacturer's directions when using the kit.

  1. Pour the specified amount of dye into the engine oil fill tube.
  2. Operate the vehicle under normal operating conditions, as directed in the kit.
  3. Direct the light toward the suspected area. The dyed fluid will appear as a yellow path leading to the source.

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 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 bent flange must be repaired also. Before attempting to repair a leak, inspect for the following conditions and correct them as they may cause a leak:

Gaskets

    • The fluid level/pressure is too high.
    • The crankcase ventilation system is malfunctioning.
    • The fasteners are tightened improperly or the threads are dirty or damaged.
    • The flanges or the sealing surface is warped.
    • There are scratches, burrs, or other damage to the sealing surface.
    • The gasket is damaged or worn.
    • There is cracking or porosity of the component.
    • An improper seal was used.

Seals

    • The fluid level/pressure is too high.
    • The crank case ventilation system is malfunctioning.
    • The seal bore is damaged, scratched, burred, or nicked.
    • The seal is damaged or worn.
    • Improper installation is evident.
    • There are cracks in the component.
    • The shaft surface is scratched, nicked, or damaged.
    • A loose or worn bearing is causing excess seal wear.