Rear Main Seal

The rear main seal is a circular gasket that sits at the very back of the engine, where the crankshaft connects to the transmission. Its job is to seal the gap around the rotating crankshaft and prevent engine oil from leaking out. Even though it’s small and hidden deep in the engine assembly, a failing rear main seal can cause serious leaks and messes.

Over time, heat and wear can cause the rear main seal to dry out, crack, or lose flexibility. When that happens, you might see oil dripping from the rear of the engine or pooling underneath the car. Unfortunately, replacing it usually requires removing the transmission or engine, making it a labor-heavy job. Fun fact: some cars with manual transmissions may leak from the rear main seal more quickly due to the different motion loads from the clutch system.