Causes and Fixes for Transmission Leaks

Transmission leaks are one of the most common causes of problems with a car's transmission and are also one of the most common reasons for transmission repair. Repairing leaks in your transmission can range from very simple repairs such as tightening loose transmission pan bolts or a loose drain plug, to very expensive repairs where the output seal has been damaged and needs to be repaired or replaced.

Common Causes of Transmission Leaks
There are several reasons why your transmission may leak transmission fluid. One of the most common is bolts that were not properly tightened when changing the transmission fluid filter, resulting in a loose transmission pan. Sometimes, the transmission drain plug isn't securely tightened after changing the transmission fluid or flushing the transmission. In short, the failure to securely tighten bolts on the transmission often leads to many transmission leaks that can result in major damage to the transmission.

Besides loose bolts and drain plugs, another very common reason for a transmission leak is worn out seals or gaskets. Over time, gasket seals may wear out and become frayed or cracked. When this occurs, transmission fluid will begin to seep out through the transmission pan and part of the transmission where the transmission pan is attached. Replacing a bad transmission pan gasket is a relatively simple repair, and the gasket itself will usually cost less than $20.

Although not as common as leaks caused by poor maintenance or worn out gasket seals, your car's torque converter can be a source of transmission fluid leaks as well. The torque converter is a hydraulic pump that creates pressure in the transmission and sends transmission fluid throughout the transmission system. Sometimes, faulty needle bearings or cracks in the torque converter body can cause transmission leaks that can be difficult to diagnose and expensive to repair.

Other Factors Contributing to Transmission Leaks
Another common reason for transmission leaks has to do with problems encountered while driving the vehicle. If you drive your vehicle on surfaces that have large stones or rocks, the bell housing of your transmission may be struck by a large rock or stone and be cracked or damaged. This will often result in an immediate and significant loss of transmission fluid and may result in the vehicle not being able to be driven at all.

Other parts of a transmission that are commonly damaged by rocks and debris on the road are the transmission fluid lines. Transmission fluid lines are usually made out of steel or aluminum and are very durable; however, large rocks or debris that strike the fluid lines can cause cracks or punctures in lines, resulting in a leak. Damage caused to a vehicle transmission by rocks and debris may be difficult to repair and may require that the transmission be replaced.

How to Repair a Transmission Leak

If you've tried a gasket replacement and see transmission fluid is still leaking out, there may be something else going on. A simple check of everything from your repair can help you quickly locate the problem.

Transmission Pan
The transmission pan gasket mating surface could be warped. This would prevent the gasket from sealing properly, allowing fluid to escape. When replacing any gaskets, always check all surfaces for warping or other damage to the surfaces that can keep the gasket from sealing.

Transmission Bolt Torquing
Whether too tight or too loose, if the bolts that hold the transmission pan on are torqued improperly, there could be a negative effect. If the bolts are too tight, you can warp the pan. If the bolts are torqued too loosely, they won't properly hold the transmission pan in place. Check your owner's manual or a repair guide for your specific vehicle for the proper torque.

The Environmental Consequences of Transmission Leaks

Transmission leaks cause problems not only for your vehicle, they are also a significant concern for our environment. In fact, transmission fluid that has leaked from faulty transmissions is as much a concern for our environment as other petroleum based products such as gasoline or motor oil. Left unattended, transmission leaks may cause irreparable damage to an ecosystem or environment.

Good for Your Car but Not the Environment
Transmission fluid that leaks from the vehicle transmissions can cause a variety of environmental problems that are difficult to clean up or correct.

Transmission fluid contains many of the same pollutants and toxins that engine oil or gasoline contain. When these pollutants and toxins are leak, ground soil is contaminated and may result in the death of insects or animals that burrow and live in the soil. Many times, insects and animals that live in the contaminated soil will kill various types of predator insects or rodents that are needed to maintain balance in the food chain. Contaminated soil may lead to the poisoning of insects and rodents needed to control pests that can damage crops or spread disease.

Transmission Fluid Is a Danger to Our Water Supply
Leaked transmission fluid may find its way into groundwater and may eventually wind up in watering holes for livestock or even wells used for drinking water. Even if a transmission leaks fluid onto asphalt or concrete, it can find its way into water that is consumed both by animals and humans. Rains can carry toxic chemicals into reservoirs or waterholes. In short, transmission fluid leaks will almost always find its way into a water source.

How to Protect our Environment
In order to avoid the many problems that transmission fluid poses to our environment, you should always properly maintain your vehicle's transmission. Check the fluid level of your transmission often to ensure that it is full and remains that way. Check underneath your vehicle for any signs of transmission fluid leakage. Transmission fluid leaks will usually appear to be bright or dark red and are easily seen once a vehicle is moved. If your transmission is leaking, be sure to get the seals and gaskets in the transmission replaced as soon as possible.