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Repairing a leaky transmission is often a matter of replacing the transmission pan gasket. In most cases, a visual inspection is all that’s required to diagnose the issue.



What is a Transmission Pan?

The transmission pan and gasket keeps automatic transmission fluid in the transmission, where it belongs, and off the ground. Repairing a transmission pan leak is often as easy as replacing the pan gasket, assuming the pan itself remains free of damage. Removing the transmission pan may also allow you to see and repair your transmission’s internal components as well.

The transmission pan is vulnerable to damage from several sources, including speed bumps and curbs. If damage to the pan itself is causing the transmission to leak, the old pan will need to be replaced.

How does the Transmission Pan Work?

The pan has two main roles. When it’s attached to the transmission, the pan holds automatic transmission fluid. When it’s removed, the pan allows access to the transmission’s internal components without removing the rest of the transmission.

The transmission pan may have a drain plug, or the pan may need to be removed and drained during service. The pan gasket must be replaced whenever the transmission pan is removed from the vehicle.

How is The Transmission Pan Made?

Transmission pans are made of stamped steel or cast aluminum. It’s more common to find cast aluminum transmission pans, complete with cooling fins, on European vehicles. Gaskets, including transmission pan gaskets, are often made of rubber, silicone, and steel-reinforced composite materials.

Why does the Transmission Pan Break? Why does the Transmission Pan Gasket Fail?

  • The transmission pan itself may become damaged during an accident.
  • Off-road driving without sufficient ground clearance often results in damage to the vehicle’s undercarriage, including the transmission pan.
  • Under normal driving conditions, a combination of age, heat, and vibration causes the transmission pan gasket to wear out and leak.

What are the Symptoms of Transmission Pan or Gasket Failure?

  • Automatic transmission fluid (ATF) spots or puddles underneath the vehicle.
  • The transmission may slip due to clutch wear, caused by insufficient fluid.

What are the Implications of a Leaky Transmission Pan or Gasket?

  • Fluid leaks cause damage to driveways, roads, and parking lots.
  • Excessive clutch wear due to a lack of ATF.
  • The transmission may need to be rebuilt or replaced if sufficient fluid loss occurs.

A small leak may turn into a large leak as you’re driving, and you may not notice it until it’s too late. Fluid leaks should be diagnosed, either by yourself or a professional mechanic, as soon as you notice them.

If you have questions or concerns about transmission pans, gaskets, or any of your vehicle’s components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.