2000 Chevrolet Blazer - Transmission Extension Housing Gasket/Seal

Transmission Extension Housing Seal Replacement

The automatic transmission extension housing seal, also referred to as the rear shaft seal, prevents transmission fluid from leaking out of the transmission where the output shaft extends from the transmission housing. There is typically one seal at the input shaft to prevent leaks around the torque converter, but in rear-wheel drive vehicles, there is also a transmission extension housing seal installed around the driveshaft and transmission output shaft. These extension housing seals are typically made of metal and rubber and must be press-fit to the transmission to keep them securely in place. If the extension housing seal fails or wears out, it can lead to transmission fluid leak near the back of the transmission. Any loss of transmission fluid can eventually lead to performance and shifting issues, and if not addressed, may result in transmission malfunction or damage. Symptoms of a failing extension housing seal can include visible fluid leaks underneath the vehicle, particularly where the transmission connects to the driveshaft, or low transmission fluid levels. Failing to top off transmission fluid levels due to a leaking transmission extension housing seal can also cause trouble shifting gears, hesitation when accelerating from a stop, and burnt-smelling transmission fluid. Replacing the extension housing seal often involves removing the driveshaft from the rear of the transmission to allow the old seal to be removed and the new one to be installed using an appropriate driving tool to fit around the collar of the new seal. If you notice leaks near the rear of your transmission, check your extension housing seal and replace it if it is torn, damaged, or seems to be leaking around the driveshaft. For your next transmission repair, shop O'Reilly Auto Parts for transmission extension housing seals, transmission fluid, and more for a complete repair.