Transmission Fluid Leakage in Torque Converter Area: Notes

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

Fig 1: Identifying Transmission Fluid Leakage In Torque Converter Area

Courtesy of FORD MOTOR CO.

1. Transmission fluid leaking by the pump seal lip tends 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 is deposited on the inside of the torque converter housing only, near the outside diameter of the housing.
2. Transmission fluid leakage by the outside diameter of the pump seal and pump body follows the same path as leaks by the inside diameter.
3. Transmission fluid leakage from the converter seal weld or converter to flexplate stud weld appears at the outside diameter of the torque converter, on the back side 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.
4. Transmission fluid that leaks by a pump to case bolt or pump gasket is deposited on the inside of the torque converter housing only. Transmission fluid is not deposited on the back of the torque converter.
NOTE: White facial tissue aids in determining the color (transmission fluid is red) and source of the leaking transmission fluid.
5. Engine oil leaks are sometimes incorrectly diagnosed as transmission pump gasket leaks. Check the following areas of possible leakage to determine if engine oil leakage is causing the concern.
   • 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.
   • Oil galley plug leaks allow oil to flow down the rear face of the cylinder block to the bottom of the torque converter housing.
   • Leakage at the crankshaft rear oil seal works back to the flexplate, and then into the torque converter housing.