5 Causes of Car Automatic Transmission Fluid Leaks

Last Updated on February 7, 2019 by themechanic

The automatic transmission is a revolutionary invention of the auto industry. It makes driving so much easier than using a manual transmission. However, there are a lot of vital components inside an automatic transmission. These are moving components which tend to rub against each other and produce heat. This is like how the engine has moving components which create friction and heat too. An engine uses oil to lubricate its components and keep them from overheating. As for the automatic transmission, it uses specially formulated transmission fluid to lubricate its components and cool them down. This fluid prevents the transmission from overheating. It also assists in sustaining the performance of the engine.

Most people never bother changing their transmission fluid. After all, you don’t need to change transmission fluid as often as you need to change engine oil. Many car manufacturers will recommend changing the transmission fluid every 100,000 miles. Since most people sell or trade their vehicles before they even reach 100,000 miles, it is never a problem for them. However, that doesn’t mean transmission fluid leaks won’t occur at some point. If they do, it can damage the transmission and cause problems with setting the right gears automatically.

5 Common Causes

To repair an automatic transmission fluid leak, you need to know where the leak is coming from. This means figuring out the cause of the leak and stopping it from leaking any more transmission fluid. The remedy may involve repairing or replacing certain components in the transmission system which carries or stores this fluid.

Below are the top 5 causes of an automatic transmission that leaks fluid.

1) Bad Transmission Seals – Hydraulic pressure must be sustained in the transmission. That is the responsibility of the transmission seals. However, there is a lot of heat generated by the transmission whenever it’s in use. After a while, this heat will tear down the transmission seals until they start to crack and get worn out. If this happens, transmission fluid will leak through the seals. Check all the seals if you notice leakage, including the output shaft seal, tail housing seal, and the plug seal.

2) Bad Transmission Pan – The transmission pan stores the transmission fluid that is used by the transmission. This pan features several small plugs and bolts which prevent leakage. Unfortunately, these plugs and bolts can wear out and get damaged as time goes on. They may even get loose too. In any of these situations, it will cause fluid to leak through the pan. You will need to inspect the pan and fix whatever is causing the leak. This may involve tightening the plugs and bolts or simply replacing them entirely.

3) Bad Transmission Fluid Line – The transmission fluid line has an important job of transferring transmission fluid within the system. For this reason, it is constructed from a durable material such as steel or aluminum. But as tough as this material is, debris and heat can wear it down. If it wears down too much, the line will form cracks in it. Then you will have a transmission fluid leak there. The fluid line will need to be replaced.

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4) Bad Torque Pump – The torque pump is what allows the transmission fluid to circulate and move through the transmission system. If your pump gets damaged or wears out, it will leak transmission fluid. This will cause an even worse problem because then the fluid won’t be able to circulate through the system. You’ll have huge gear setting difficulties once this happens.

5) Bad Transmission Pan Gasket – The transmission fluid is stored in something called a transmission pan. Any vehicle with an automatic transmission will have one of these pans in it. The transmission pan gasket is basically a mechanical seal which lies in the middle of the transmission and pan. When transmission fluid from the pan flows to the transmission, this gasket ensures the fluid does not leak out during this process. But if you have a bad gasket that has cracks or tears in it, the fluid will leak out.

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