Moving your vehicle on the driveway only to find a small puddle of oil left behind is a serious reason for concern. Considering just how important oil is for the healthy operation of the engine, any leaks need to be addressed as soon as possible.
The main symptom of the rear main seal leak is forming an oil puddle beneath the spot where transmission and engine are merged. Even though the parts won’t cost more than $100, the cost of labor is what makes the rear main seal repair very expensive. Mechanics will charge between $500 and $1800 for the labor alone, with the average total cost of repair being $1100.
The rear main seal can be found at the rear end of the engine, where it connects to the transmission. In longitudinally mounted engines, the seal is located towards the back of the engine bay, while transversely mounted engines have the seal facing the left or right wheel arch.
The seal is just like any other synthetic rubber ring and prevents the oil seal within the engine, and it’s made very durable to last as long as possible. What’s special about the rear main seal is that it’s very difficult to gain access to, and requires you to remove the transmission, and sometimes even the engine.
Oil consumption and forming of oil puddles underneath the vehicle can signal early-stage failure of the rear main seal. However, with how expensive the rear main seal is to replace, you should rule out everything else before making a conclusion.
The location of the rear main seal leak will be at the bottom of the transmission bell housing, where it comes in contact with the engine. This is not a definitive sign, as leakage from other components may drip down towards the bell housing and lead you to a false conclusion.
Valve cover gasket, intake manifold gasket, and distributor gasket should all be ruled out, especially if you find oil dripping on the top of the bell housing. The leak at the rear of the oil pan gasket is often confused with a rear main seal leak, so inspect it thoroughly to rule it out. Bottom line is, almost any other cause for oil leak is cheaper to repair than replacing the rear main seal.
Leaking oil, especially when it’s dripping in very small amounts will stick to engine parts and burn under high operating temperatures. This will cause a heavy smell of burning oil, rarely noticeable inside the cabin, but you’ll be able to tell something is wrong once you lift the hood.
The old school drivers and mechanics have taught me most of what I know about cars, and one of the first lessons was on what to do when the engine oil light comes on. If the light flashes on the dashboard, bring the vehicle to a stop as soon as possible and shut off the engine.
You don’t know whether there’s a minuscule oil drip that the sensitive sensor of your modern car has registered, or if there’s a huge gasket rupture that has drained your engine of oil in a matter of seconds. From the moment the light comes on, every rotation of the engine is critical as it may be running dry.
Check underneath the car for oily components and leaks, and if you can, inspect the road for oil spills. From this point on, how you approach the problem can determine how costly the repairs will be.
The safest thing to do is call on-road assistance and get your vehicle towed to a mechanic for inspection and repairs. If you don’t see any leaks and decide to ignore the issue, it may be nothing, or you might drive your engine into seizing and turn it into scrap metal. Ultimately, the choice is yours, but I would strongly advise spending whatever it costs to ensure your engine has a sufficient amount of oil inside it.
Unfortunately, the rear main seal repair cost is one of the more expensive jobs on the vehicle. The frustrating fact is that the seal itself costs only $10 – $100 on Amazon or Walmart, while the labor can easily cross $1,000. AutoServiceCost has created a great analysis of the costs, and you can find some of the information in the table below.
| Mechanic | Warranty | Cost |
| Midas | 1 Year | $650 – $1800 |
| NAPA | 2 Years | $700 – $1550 |
| Mr. Tire | 1 Year | $630 – $1800 |
| Your Mechanic | 1 Year | $700 – $1650 |
We sometimes forget or take for granted the skills required to be a successful mechanic. Even though the powertrain is very durable, it’s not a crude lump of metal and requires delicate hands to repair without damage. Also, take into account the investment into professional tools the mechanic has to make to be able to work on the rear main seal.
Your mechanic shouldn’t and most likely won’t trust your diagnosis, and instead check what the problem is personally. Once he’s sure the rear main seal is the cause of the leaks, he needs to remove the transmission and the flywheel/flexplate before he can access the seal housing.
The process takes hours, and every part needs to be thoroughly cleaned and carefully handled. With the rear main seal replaced, everything has to be put back into its place before another round of testing determines whether the repair was a success.
Oil leaks always have a high risk of damaging the engine if too much oil is lost. The bad rear main seal will only continue to deteriorate over time, and you cannot predict with certainty when it’s going to let more oil out and drain the engine. You can postpone the repair by adding more oil to the engine – something we’ve covered in our article titled: “Can You Add Oil To A Hot Engine? Should You Let It Cool?“.
You can not, as the seal sits between the engine and the transmission. Although rare, some cars require you to remove both the transmission and the engine to work on the rear main seal.
Provided that the mechanic has the replacement rear main seal and no other vehicles in the queue, the job can be done within an 8-hour shift. However, this is highly unlikely, as the mechanic will first have to wait for the seal to arrive, then clear his queue before he gets to your vehicle.
Replacing the rear main seal is very expensive, and unfortunately, has to be done before any damage is caused to other engine components. The only advice I can give you is to call every mechanic within your area and compare prices, warranty, and delivery date to get the best deal possible.
Find more insightful topics to read:
Transmission Fluid Leak When Parked: Causes and Fixes
What Causes a Crankshaft Seal to Leak? Symptoms And How To Fix
Why Is Gas Leaking From the Bottom of My Car?
