What is a transmission filter for?

A transmission filter prevents dirt and debris from getting into the gears and other parts of the transmission system. It is positioned above the transmission pan, which collects excess fluid, and below the pickup tube that connects to the oil pump, which regulates the pressure of fluid in the transmission. The filter collects contaminants before letting fluid through to the transmission, stopping the buildup of sludge, which can cause excessive wear on the transmission’s moving parts.image of transmission filter

How does a transmission filter work?

How a transmission filter works is a relatively straightforward process with few parts involved. Sometimes a transmission filter change involves more than just replacing the filter. Oftentimes there is a fluid filter kit involved that allows for some other key filtration system parts to be replaced while the transmission is open and easily accessible. These parts include:

  • Transmission filter – The filter looks like a metal plate with slats. Inside the slats is a fibrous material that collects contaminants before the fluid goes into the transmission.
  • Gasket – A rubber gasket ensures a tight seal between the transmission filter assembly and the transmission pan. This ensures that no fluid escapes while it is moving through the filter.
  • Pickup Tube – A tube that connects the transmission filter assembly to the oil pump.
  • Seal – A rubber o-ring that seals the fit between the pickup tube and the transmission case. This ensures no loss of fluid or pressure.

When do you change the filter?

Over time, tiny bits of metal and other grit and dirt build up in a transmission filter. Although every vehicle has its own maintenance schedule that can usually be found in the owner’s manual, the transmission filter and fluid should be replaced every 30,000 to 100,000 miles. It really depends on the make, model, and age of your vehicle, but short of between 30,000 and 100,000 miles is a pretty good window to operate within. Changing the fluid and filter can be a messy and time-consuming job because few transmissions are equipped with a drain plug. That means the transmission pan must be removed in order to reach the transmission filter and allow old fluid to drain. This is often in a hard-to-reach area and requires special tools.

What are signs that the transmission filter needs to be changed?

If you experience any of the following symptoms, schedule an appointment with your locally owned and operated AAMCO Colorado transmission repair shop. We’ll do a thorough inspection and run diagnostics to find out what is wrong and what needs to be done.image - transmission fluid draining from pan under car on lift


If you hear clunking or rattling, or if the transmission shifts hard with a jarring affect, you might want to check the transmission filter. By checking the filter, you also get a look at the transmission fluid itself. If the filter or the fluid show signs of excessive dirt and wear, bring your car to AAMCO for a transmission flush. We’ll replace the fluid, filter, and inspect your car for any other potential issues.


If the transmission filter is not fitted properly or there is a malfunction in the transmission itself, it could result in leaking fluid. There are a number of seals and gaskets throughout the transmission that can develop cracks and cause a leak. If those gaskets become loose or misaligned, fluid can leak. Signs of leaks will be noticeable on the ground when you park your car for a while (overnight, for instance), then move it.


The purpose of the transmission filter is to keep contaminants out of the transmission fluid. If the filter fails to do its job properly, the transmission fluid will become too dirty to do its job efficiently. If dirt and sludge reach a critical level, it can burn and even lead to costly transmission repairs. Check the transmission fluid regularly, both for correct level and for color. If it’s not reddish in color and fairly clear or clean looking, it’s time to consider a transmission fluid flush.

Can’t Change Gears

If you’re unable to change gears easily (from park into drive, reverse, etc.), or the transmission struggles to change gears either while you are moving or parked, there might be a problem with the transmission filter. If the gears grind for no reason or the vehicle surges when the gears are changed, the problem may be a result of a dirty or malfunctioning transmission filter. This is something you want to have checked out immediately by a certified transmission technician. Schedule an appointment now.

Burning Smell or Smoke

When the filter has become blocked with particles, dirt, and sludge, it can result in a burning smell – especially if the transmission fluid itself needs to be change. In extreme cases, a clogged filter that is causing a burning smell can result in smoke coming from the engine. Contact your local AAMCO Colorado transmission shop for an appointment if you have smoke coming from your engine.

AAMCO Colorado Keeps You Informed

At AAMCO Colorado we take great care to keep you informed about your car and all its systems, as well as keep your car on the road with scheduled maintenance services and repairs, including full transmission repairs and rebuilds.

If you are experiencing any problems with your car, bring it to your local AAMCO Colorado Transmission and Total Car Care center for a complete Vehicle Courtesy Check diagnositc. We’ll help you keep your car running reliably and safely through all seasons, all weather.

If you have questions about your car’s transmission, road readiness, or about car repair and maintenance topics, AAMCO Colorado can help. You can also go online and use the AAMCO Colorado Ask a Mechanic feature to submit your auto repair questions. They will be answered by a real AAMCO Colorado mechanic as soon as possible.

Related Articles About Car Maintenance & Repair

Transmission Not Shifting Smoothly?

Take Care of Your Transmission

Common Transmission Problems that Mean Trouble

Locally Owned & Operated AAMCO Colorado Transmission Repair Shops

View AAMCO Colorado Locations in a larger map.