Info - Transmission Fluid Leak Diagnosis

This bulletin is being revised to add the 2006 model year, HUMMER H3 and Saab 9-7X vehicles. Please discard Corporate Bulletin Number 01-07-30-041A (Section 07 - Transmission/Transaxle).

The purpose of this bulletin is to provide assistance for technicians when diagnosing fluid leaks on automatic transmissions. It has been found that many of the transmissions returned to the Warranty Parts Center (WPC) for fluid leaks were determined to be no trouble found (fluid leaks could not be found). To reduce unnecessary transmission replacement, please use the following information.

If the customer concern is a leak, the source of the leak must be isolated. There are many components on a vehicle that can produce leaks:

It is important to note that leaking fluids can migrate toward the rear of the vehicle. This can make isolating the leak very difficult. Generally, the fluid path can be followed to the leaking component during a visual inspection. Once the leaking component has been identified, use the J 42220 Leak Detection Lamp and the J 28431-6 Leak Dye Kit to isolate the leak point.

If the leaking component cannot be identified, use the leak dye in components that are in the fluid path. The Service Information contains procedures for diagnosing leaks and also alternate methods for leak detection.

Most leaks at seals and gaskets can be repaired on-vehicle. These procedures are located in the appropriate sub-section of the Service Manual and use the time from the applicable Labor Time Guide (LTG). If the transmission case is leaking due to porosity, the transmission typically needs to be replaced.

All components that are diagnosed and that require replacement due to leakage must be diagnosed with the leak dye and a leak detection lamp.

Upon receipt and inspection at/by WPC, components that do not exhibit leaks will be brought to the attention of the Regional Warranty Manager for appropriate action.