The object of any filter, and it doesn’t matter if it’s the filter in your automatic washing machine or the filter in your automatic transmission, is to capture contaminates; in one case it is lint, in the other case it is small shards of metal that wear from the components in the transmission. The majority of automobile manufacturers suggest automatic transmission filters be changed every couple of years. As the filter in most automatic transmissions cannot be accessed without removing the bottom pan, when the filter is changed it is an ideal time to change the fluid and pan gasket as well.
There are a few signs that indicate it is time for a filter change:
Problems changing gears:
Under normal conditions, a vehicle equipped with an automatic transmission should shift gears seamlessly. If your car begins to hesitate to shift or it will not change gears at all there is definitely a problem, and in many cases the problem is the transmission filter.
If you begin to hear odd rattling noises coming from the transmission it could be a number of things; it could be loose fasteners that are simple to deal with or it could be that the transmission filter is plugged with metal shavings and debris.
Burning smell or evidence of smoke:
Once automatic transmission filters become clogged the contaminates that it is designed to collect are not picked up, the result is usually a burning smell or smoke. This is a problem that must be corrected quickly; things can go from bad to worse in a matter of a few miles.
You might wonder how transmission fluid can become contaminated when you know it is a sealed unit. It may be sealed but there is a dip stick to check the fluid level and a fluid top-up tube. It does not take much for oil and grease from the engine to enter through these ports.