The cause of most external leaks can generally be located
and repaired with the transmission in the vehicle.
General Method
- Verify that the leak is transmission oil.
- Thoroughly clean the suspected leak area.
- Operate the vehicle for about 15 minutes or until normal operating
temperatures are reached.
- Park the vehicle over clean paper or cardboard.
- Turn the ignition to the OFF position.
- Look for oil spots on the paper.
- Make the necessary repairs.
Powder Method
- Thoroughly clean the suspected leak area with solvent.
- Apply an aerosol type powder (foot powder) to the suspected leak
area.
- Operate the vehicle for about 15 minutes or until the normal operating
temperatures are reached.
- Turn the ignition to the OFF position.
- Inspect the suspected leak area.
- Trace the leak path through the powder in order to find the source.
- Make the necessary repairs.
Dye and Black Light Method
- Follow the manufacturer's recommendation for the amount of dye
to be used.
- Find the leak with a black light.
- Make the necessary repairs.
Gasket and Seal Checks
Once the leak has been pinpointed and traced back to the source, determine
the cause of the leak in order to repair the leak properly. If a gasket is
replaced, but the sealing flange is bent, the new gasket will not repair the
leak. Repair the bent flange before attempting to repair a leak. In order
to prevent leakage, correct any of the following conditions.
| • | Check the gasket areas for the following conditions that may cause
a leak: |
| - | The fluid level or pressure is too high |
| - | A plugged vent or drain-back holes |
| - | Improperly tightened fasteners or dirty/damaged threads |
| - | Warped flanges or warped sealing surfaces |
| - | Damaged or worn gaskets |
| - | Cracking or porosity of the component |
| - | Improper sealant used (where applicable) |
| • | Check the seal areas for the following conditions that may cause
a leak: |
| - | The oil level or pressure is too high |
| - | A plugged vent or drain-back hole |
| - | A damaged seal bore (scratched, burred, or nicked) |
| - | Cracks in the component |
| - | The manual or output shaft surface is scratched, nicked, or missing |
| - | A loose or worn bearing causing excess seal wear |
Possible Points of Oil Leaks
Oil leaks may occur in the following areas:
| • | The transmission or the transmission oil pan |
| - | Attaching bolts are not tightened to the correct specification. |
| - | A gasket is improperly installed or damaged. |
| - | The oil pan or mounting face is not flat. |
| - | The filler tube multi-lip threads are leaking. |
| - | The governor cover or O-ring is damaged or missing. |
| - | The filler tube bracket is misaligned. |
| - | The vehicle speed sensor seal is damaged. |
| - | The manual shaft seal is damaged. |
| - | The oil cooler connector fittings are loose or damaged. |
| - | The propeller shaft oil seal is worn or damaged. |
| - | The governor cover is leaking. |
| - | The line pressure pipe plug is loose. |
| - | Check the converter hub for damage. |
| - | The bushing is moved forward. |
| - | The bushing is damaged. |
| - | The garter spring is missing from the seal. |
| - | The converter leaks in the weld area. |
| - | The casting in the case of the pump is porous. |
| • | The vent pipe or the fill tube |
| - | The transmission oil level is too high. |
| - | Water or coolant is in the oil. |
| - | The oil level indicator is incorrect. |
| - | The transmission vent is plugged. |
| - | The drain back holes are plugged. |
| - | The oil pump to case gasket, if equipped, is misaligned. |
