Transmission Filter Replacement

Transmissions are hydraulically controlled components, and therefore use fluid to build the required pressure and to prevent overheating. Although new transmission fluid is clean, the internal components of the transmission are not. As the fluid travels throughout the transmission, it collects various deposits. The fluid is then routed to a filter, which removes those contaminants. As with any other type of filter, the filter itself eventually becomes dirty and it can no longer filter the fluid. For this reason, the transmission's filter must periodically be replaced.

Safety Considerations
A hot transmission can produce transmission fluid hot enough to easily burn skin, so allow the vehicle to sit for at least three hours while the engine is turned off to allow the fluid to cool. Raise the vehicle with a floor jack, then place a single jack stand at each corner of the vehicle underneath the vehicle's frame to safely support the vehicle's weight.

Removing the Transmission's Pan
To access the filter, the transmission's pan must be removed. However, because the transmission is full of fluid, it is necessary to first drain the fluid. Place a drain pan underneath the transmission pan, then remove the single drain bolt from the transmission's pan with a wrench and allow the fluid to drain into the drain pan. The transmission's pan is located on the bottom of the transmission. After the fluid has drained out of the transmission, install and tighten the pan's drain bolt with a wrench to avoid losing it. Remove the bolts that surround the lip of the pan with a wrench by turning each bolt in a counterclockwise direction, then pull the pan off of the transmission to reveal the transmission's filter.

Replacing the Transmission Filter
Once the transmission's pan is removed, changing the pan is simply a matter of disconnecting the old filter and bolting a new filter in its place. Remove the filter's retaining bolts with a wrench, then pull the filter out of the transmission. The filter is a large metal plate that typically has a near-rectangular shape, depending on the type of transmission. Place the replacement filter against the bottom of the transmission, ensuring that the bolt holes on the filter align with the bolt holes on the bottom of the transmission. Install and tighten the filter's retaining bolts with a wrench.

Installing the Transmission Pan
Installing the pan is fairly straightforward, but it is important that a new gasket be used. Peel the transmission's old pan gasket from the outer lip of the pan, then wipe down the lip of the pan with a clean, lint-free rag. Coat one side of the pan's gasket with gasket sealer, then place the coated side of the gasket against the lip of the transmission's pan. Coat the opposite side of the gasket with gasket sealer, then press the pan against the bottom of the transmission, ensuring that the bolt holes on the pan align with the holes on the transmission. Install and tighten the pan's retaining bolts with a wrench.

Filling the Transmission with Fluid
Consult the vehicle's owner's manual to determine how much transmission fluid should be added to the transmission, then lift the vehicle's hood and withdraw the transmission's dipstick. Place a funnel into the dipstick tube, then pour the appropriate amount of transmission fluid into the funnel. Remove the funnel and insert the dipstick back into the dipstick tube to complete the replacement.