4 Signs of a Bad Transmission Pump

The gear shift of a manual transmission.

The transmission pump is an oil pump that circulates transmission fluid through the valve body, which in turn controls the clutches and the bands that control the planetary gear sets. This part is crucial to the overall functionality of your vehicle’s transmission, so when it begins to fail, your transmission itself will soon follow if you don’t get it repaired or replaced. Should the transmission pump begin to fail, it will become apparent in the following ways.

1. Check Engine Light

A telltale sign of car troubles is the illumination of the check engine light. Since this can actually indicate a multitude of issues with your car, you will have to have a machine that can read the specific error code that tells you the problem. You can get your own diagnostic machine to read the error code or you can take it into a dealership or a repair shop to have them read it for you.

2. Burning Smell

When your pump starts failing, the fluid in the pump will obviously not be circulating into the transmission like it’s supposed to. As a result, the transmission will begin to overheat and the fluid will burn. The smell will be easiest to identify when you check the fluid dipstick, and the fluid itself will be darker than normal.

This symptom can also happen when your fluid levels are too low, so make sure first that this is not the case.

3. Harsh Shifting

When transmission fluid isn’t being pushed into the transmission, the gears are not being properly lubricated, which can lead to hard shifting. An automatic transmission will jerk or hesitate when you’re accelerating.

4. Transmission Noise

When the gears and clutch packs are not being lubricated by fluid being pumped into the transmission, they will also have problems with making noise due to a lot of friction being created as the transmission operates. The noise will become more noticeable after the friction has caused premature wear on the parts, resulting in more space between the clutch pack friction plates resulting in excessive slippage.

As mentioned previously, a bad transmission pump can lead to problems with the rest of the transmission, but conversely, other problems with the transmission can be what causes the failure of the pump. Issues with low fluid, contaminated fluid, or worn parts can make your pump work that much harder and eventually fail, so be sure that you stay on top of any repairs your transmission needs to avoid problems.