Transmission Fluid Leakage in Torque Converter Area

In diagnosing and correcting transmission fluid leaks in the pump support and gear and torque converter area, use the following procedures to locate the exact cause of the leakage. Leakage between the transaxle and engine, as evidenced by fluid around the torque converter housing, may have several sources. By careful observation it is possible, in many instances, to pinpoint the source of leakage before removing the transaxle from the vehicle. The paths which the fluid takes to reach the bottom of the torque converter housing are shown in the illustration. The 5 steps following correspond with the numbers in the illustration.

Fig 1: Identifying Torque Converter Fluid Leakage Area

Courtesy of FORD MOTOR CO.

1. Transmission fluid leaking by the pump seal lip will tend to move along the impeller hub and onto the back of the impeller housing. Except in the case of a total seal failure, transmission fluid leakage by the lip of the seal will be deposited on the inside of the torque converter housing only, near the outside diameter of the housing. Transmission fluid from the vent assembly may move along the impeller hub and onto the back of the impeller housing. Transmission fluid from a converter hub weld leak will move along a path on the inside of the converter housing.
2. Transmission fluid leakage by the outside diameter of the pump seal and pump body will follow the same path that leaks by the inside diameter of the pump seal follow. Transmission fluid from a converter hub weld leak will move along a path on the inside of the converter housing.
3. Transmission fluid that leaks by a pump-to-case screw or pump gasket will be deposited on the inside of the torque converter housing only. Transmission fluid will not be deposited on the back of the torque converter.
4. Transmission fluid leakage from the converter drain plug, (model-dependent) converter seal weld or converter-to-flexplate stud weld will appear at the outside diameter of the torque converter on the back face of the flexplate, and in the converter housing only near the flexplate. Transmission fluid leaks from the torque converter will leave a ring of transmission fluid around the inside of the torque converter housing.
NOTE: White facial tissue paper may aid in determining the color (red is transmission fluid) and source of the leaking transmission fluid.
5. Engine oil leaks are sometimes incorrectly diagnosed as transaxle pump gasket leaks. The following areas of possible leakage should also be checked to determine if engine oil leakage is causing the concern.
   1. Leakage at the valve cover gasket may allow oil to flow over the torque converter housing or seep down between the torque converter housing and cylinder block causing oil to be present in or at the bottom of the torque converter housing.
   2. Oil galley plug leaks will allow oil to flow down the rear face of the cylinder block to the bottom of the torque converter housing.
   3. Leakage at the crankshaft rear oil seal will work back to the flexplate, and then into the torque converter housing.