Rear Main Seal Leak Symptoms: Causes and Replacement Costs

The rear main seal is an essential component of a car and helps prevent oil leakage. It connects with the transmission and the engine of a vehicle to keep the engine oil secure in place. Over time, this seal can become loose, stretched, or worn out and cause leakage. 

Diagnosing the problem can be challenging as the oil leaks nearby the transmission and can fall onto surrounding components. Below is our guide to accurately identifying the problem and some common causes behind the problem.

Symptoms of a Rear Main Seal Leak

Due to its location and hidden mechanisms, especially when you don’t know much about cars. However, like other mechanical components, it drops off signs and symptoms that can help you identify the problem without unscrewing the parts. Below are some common symptoms a leaky rear main seal will have:

Oil Puddles: 

This is one of the common signs as it is related directly to a fault in the rear main seal. Where you find oil puddles may vary with different cases as it can cause oil to leak from other parts. Make sure to trace the oil puddles back to their origin so you can diagnose the problem accurately. 

Smoke from underneath: 

There is smoke from the tailpipe, and then smoke comes from under the vehicle. Differentiating between the two is very easy because of the location. A rear crankshaft seal that is continually leaking may also end up dripping on the car’s exhaust system. This will cause unneeded oil to burn up and cause smoke that comes out from the underside.

Dirt and Debris:

 Wherever there is oil, it will attract all types of dirt, dust, and grime. Simply check for dust accumulation or another form of dirt near the transmission and the engine. If you see a lot of it collecting together, it is a good indicator of the problem. 

Rear Leading Seal Leak Causes

Incompatible Engine Oil:

 Using either the wrong type of oil or one of good quality can deteriorate the seal over time. Along with this, constantly running on low oil levels can also cause the seal to go through corrosion and break down due to excessive friction. 

Worn out Main bearing:

Every engine has its main bearing that keeps the crankshaft secured in place as the engine runs. A damaged or worn-out primary approach will cause the rear crankshaft seal to hang loose, causing it to become stretched and incapable of sealing in the oil. 

Damaged Crankshaft: 

The crankshaft is an integral part of the rear crankshaft seal lip, and any friction, wear and tear or damage on it can cause a leak in the rear main seal too. In this case, you may need to install a sleeve kit to restore the surface.

Rear Main Seal Replacement Cost

Any damage to the rear main seal is usually bad news; it is expensive and can cost you at least $600 in replacement. If there is a rupture inside the car’s engine or another component attaching to it, the replacement cost for a new rear main seal and any labor cost can add up to about $600-$900.