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One of the worst things that can happen to a car is a failure of the rear main seal. In older vehicles, the cost of this repair is often greater than the actual value of the car. The rear main seal exists in the back of the engine, around the crankshaft. Its primary purpose is to keep oil sealed inside the back of the engine, which is where the crankshaft and the transmission meet. The reason it is such a costly repair is that replacing it often involves dismantling the transmission and even part of, or all of, the engine. If this malfunction goes unnoticed, permanent engine damage can occur, which can make the vehicle beyond repair.

Using the recommended oil for your car’s engine is a critical step to try to keep your rear main seal functioning the way it should. It is also crucial to check your oil and change it as needed, as low oil levels can cause issues with the rear main seal. Excessive heat, old age, high mileage, infrequent use, and worn bearings can also be factors contributing to rear main seal failure. Let’s examine how to spot a rear main seal malfunction, and what to do next.

How to Identify a Rear Main Seal Leak

If your car seems to be losing oil quickly but you do not see visible leakage when your car is parked, your rear main seal could be in the early stages of failure. If you are seeing oil accumulating under the car, or noticing you need to top off your oil more frequently than usual despite not using the car more than is typical, you likely have a leak. One of the most serious signs is if your oil light comes on shortly after an oil change.

Unfortunately, this part is difficult to see and find on a car, and is not designed to be replaced easily. A simple test can be executed by idling your engine for about fifteen minutes and examining the ground underneath for any oil spillage. Running the car while it is stationary over concrete makes this easiest to spot.

Make sure to check the cover gasket and valley pan for leaks. These much simpler repairs can sometimes be misdiagnosed as a rear main seal leak. Generally, maintaining the recommended oil change schedule as well as bringing your vehicle in for regular maintenance are the first steps in keeping the seals in your car in proper working order.

What Happens if the Rear Main Seal Fails

Rear main seal leaks are so dangerous because it is possible for the leak to occur at a very fast rate. Due to the location, it is subject to high oil pressure. It is also connected to the engine, which must be slick with oil to function properly. Critically low oil levels can lead to permanent damage to your engine, and if the oil light ever comes on, it is recommended you stop driving immediately.

One of the things that makes this repair difficult and costly is the hard to access location of this seal. Usually, your mechanic will have to remove the oil pan as well as either your engine or your transmission to be able to replace the seal.

If you suspect your rear main seal is failing, the best course of action is to get your vehicle to a dealer or licensed repair shop as soon as possible.

How Glenwood Foreign Car Can Help

Glenwood Foreign Car has been servicing the areas of Upper Makefield Township, Yardley, Newtown, and Morrisville, PA since 1977. We specialize in foreign car repair, and are a great choice for anyone experiencing problems with an Audi, Mercedes Benz, Volvo, BMW, Acura, Infiniti, Nissan, Lexus, or Toyota. We use the best quality Bosch parts to ensure our repairs are long-lasting.

Glenwood Foreign Car offers all standard services—multipoint inspections, oil and filter replacement, comprehensive fluid checks, engine component checks, tire rotation and inspection, Pennsylvania state inspections, and premium auto detailing. If you need it, we also have loaner cars so you don’t have to disrupt your daily schedule while we’re working on getting your car road-worthy once more.