4 Causes of Transmission Fluid Leaks in a Pickup Truck

What are some of the known causes of transmission fluid leaks you know? Here we will go through several of them. Your truck engine is the primary power source, and the transmission ensures that the engine’s speed and torque reach the wheels. It has a gearbox with gear and gear train for the above role. The transmission is made of several gears which are joined to one another. These gears are metallic, so they need proper lubrication for long life and to function effectively.

What is Transmission Fluid?

A truck has various fluids, the transmission fluid being one of the essential fluids of your truck. This fluid lubricates the transmission system’s components to operate optimally, and this function protects and cleans the metallic surfaces from wear.

The transmission fluid also functions as a coolant in trucks with automatic transmissions. As the automatic transmission functions, it generates a lot f heat which can be harmful to the entire transmission system, and it is this fluid that absorbs the excess heat from the transmission.

4 Causes of Transmission Fluid Leaks

The transmission fluid is prone to leakages, like any other fluids in your truck. Why does the transmission fluid leak? You will understand why the transmission fluids leaks in your pickup truck as soon you finish reading this guide.

Faulty Transmission Pan Gasket

Many people forget to replace the pan gasket whenever they remove the transmission pan, and instead, they install the old one, which starts to leak very fast. A leaking fuel pan gasket is the primary cause of a leaking automatic transmission.

The transmission fluid slowly eats the pan gasket, making them develop leakages quickly. Some trucks use sealer instead of a gasket, which also becomes worn and will need to be replaced.

Rusty/Cracked Transmission Pan

If your transmission pan is made of aluminum, be assured that, at some point, it will crack. It can crack when you hit a hard object under your truck while driving.

If your transmission pan is made of steel, it will become rusty with time and develop holes. It is necessary to keep inspecting your transmission pan to detect any signs of rust and replace it before the better part of it becomes eaten up.

Leakages on the Transmission Pan Drain Plug

Some automatic transmission systems have a drain plug, but some do not. If your truck has one, it is likely to leak. The drain plug has an O-ring sealing which you should replace whenever you replace your fluid. Many forget to replace the O-ring sealing, which leads to a leaking transmission.

Blocked Transmission Ventilation

The transmission system has a breather assembly that ensures an equilibrium pressure inside the transmission system. The breather lets the transmission breathe air when there is an expansion or contraction of air, and this lets the hot air out as the cool air gets into the transmission system. The ventilation gets clogged, which results in transmission fluid leaks.


The transmission fluid is essential in your transmission system. If you realize that your transmission fluid leaks, consider checking any of the above areas as the common causes. 

Posts Tagged with… ,