Oil Leak Diagnosis
- Tools Required
- SA9175NE Black Light Kit
Most 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 procedure may help 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. At what point is the fluid leaking from? After running the vehicle at normal operating temperature, park the vehicle over a large sheet of paper. After a few minutes, you 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 all gasket mating surfaces for leaks. A mirror is useful for finding leaks in areas that are hard to reach.
NOTICE: Do not use solvents or degreasers to clean the area. These chemicals can cause seals to swell and make the leak difficult to locate.
4. If the leak still cannot be found, clean and dry the area with a shop towel. Operate the vehicle for several miles at normal operating temperature and varying speeds. After operating the vehicle, visually check the suspected component. If you still cannot locate the leak, try using the powder or black light and dye method.
Powder Method
1. Clean the suspected area.
2. Apply an aerosol-type powder (such as foot powder) to the suspected area.
3. Operate the car 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 Black Light Kit (SA9175NE) and Oil Dye (SA9176NE) or equivalent are available for finding leaks. Refer to the manufacturer's directions when using the kit.
1. Pour specified amount of dye into leaking component.
2. Operate the vehicle under normal operating conditions as directed in the kit.
3. Direct the light toward the suspected area. The dye fluid will appear as a yellow path leading to the source.
Repairing The Leak
Once 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 bent flange must be repaired also. Before attempting to repair a leak, check to make sure that the following conditions are correct as they may cause a leak.
Gasket Leaks
Check for:
- High fluid level or high oil pressure.
- Plugged ventilation filter or valve.
- Improperly tightened fasteners or dirty/damaged threads.
- Warped flanges or sealing surface.
- Scratches, burrs or other damage to the sealing surface.
- Damaged or scratched vibration damper retaining bolt/washer.
- Damaged or worn gasket.
Seal Leaks
Check for:
- High fluid level or high oil pressure.
- Damaged seal bore (scratched, burred or nicked).
- Damaged or worn seal.
- Improper installation.
- Cracks in component.
- Shaft surface scratched, nicked or damaged (refer to illustration).
- Loose or worn bearing causing excess seal wear.
Valve Guide O.D Leaks
Check for:
Oil leaking between the outside diameter of the valve guide and the cylinder head casting. (To help identify an oil leak between the outside diameter of the guide and the cylinder head casting, apply several drops of engine oil dye [SA8176NE] around the outside diameter of the valve guide and allow to sit for a minimum of three minutes. Use Black Light Kit [SA8175NE] to identify oil leak location.)
Oil leaking between the outside diameter of the valve guide and the cylinder head casting can be caused by a damaged cylinder head casting valve guide bore. If oil is leaking between the outside diameter of the valve guide and the cylinder head casting, install an oversize valve guide.