Why Crankshaft Seal Replacements Can Be Tricky

Crankshaft seals are designed to keep fluid in and dirt or contaminants out. As the engine ages due to hours and mileage, the crankshaft seal ages as well.

There are two types of crankshaft seals

  • Front cover seal (front of crankshaft)
  • Rear main seal (rear of crankshaft)

Front cover seal

The most common seal that wears out and needs replaced is a front cover seal. This seal resides in the front housing that covers a timing chain or timing belt. This seal usually gets the most abuse due to the pressure of the timing chain or timing belt and the accessories driven by the serpentine belt or v-belt.

This seal can be tricky to replace, especially if it is in a transverse engine, meaning a front wheel drive or all wheel drive mounted engine.

On a rear wheel drive vehicle, the seal replacement can be easy or difficult depending on what needs to be removed to take the cover off of the engine. For vehicles with camshaft in the block, the cover is relatively small and usually has easy access. On the other hand, vehicles with overhead camshafts of one or more or even dual heads with overhead camshafts can be difficult when changing out a seal.

Even on a transverse mounted engine, the seal removal can be tricky due to the lack of room to access the seal. This makes it harder to remove and replace the seal with using greater efforts.

When it comes to replacing the seal, the only thing to do is see if the seal is mounted from the inside of the cover or the outside of the cover. If the seal is mounted from the inside of the cover, then the front cover must be removed to replace the seal. However, if the seal is mounted on the outside of the front cover, then using a seal remover tool and removing the harmonic balancer will allow the seal removal process to be successful in a shorter amount of time and less effort.

For some vehicles, the water pump or power steering pump may be in the way of the mounting bolts to the front cover seal. This makes the seal removal process even more time consuming due to having to remove the additional components to gain access to the mounting hardware.

If the front cover was removed to install a new front cover seal, be sure to clean the inside of the cover and the gasket flange area. Clean parts ensure the engine is to be non contaminated and kept in good condition. Cleaning the gasket flange area will prevent any oil leakage during engine operation after replacing the front cover seal.

Rear main seal

The rear main seal is the most difficult seal to replace on an engine. This seal resides on the back of the crankshaft and is between the engine and transmission. It is required to remove the transmission to replace the rear main seal.

  • Note: When changing a clutch or a torque converter, it is recommended to replace the rear main seal.

If you need to replace your front crankshaft seal or need other service performed, contact one of our YourMechanic’s automotive specialists and we’d be happy to help.


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Gregory

31 years of experience
342 reviews
Gregory
31 years of experience
Land Rover Discovery - Front Crankshaft Seal - Littleton, Colorado
My experience with Mr. Hall was great. He was both knowledgeable and personable. My vehicle was repaired quickly and all is well. There remains more work to be done and I would use YourMechanic without hesitation.
Nissan Frontier - Front Crankshaft Seal - Littleton, Colorado
Greg is an excellent mechanic that I prefer for all my auto repairs. This most recent repair visit, it was freezing outside but Greg didn't hesitate crawling under my car to make the repairs in record time. In addition, I had some questions concerning other problems I was having with my cruise control, heater, and oil pressure gauge. Greg gave me some great advice for fixing those problems myself that only an experienced mechanic would know.

Harold

32 years of experience
52 reviews
Harold
32 years of experience
GMC Terrain - Front Crankshaft Seal - Jacksonville, Florida
He was the only one who actually solved the issue rather than just continuing to put a bandaid on it, good job.
Buick Century - Front Crankshaft Seal - Orange Park, Florida
Harold was friendly, professional and very knowledgeable. He worked quickly and answered any questions we had without hesitation. Really good experience overall and will definitely use his services again!

Joel

21 years of experience
967 reviews
Joel
21 years of experience
Hyundai Sonata - Front Crankshaft Seal - Jacksonville, Florida
Quality professional work was completed well within the allotted time. Courteous and professional. Has my highest recommendation.

Nathan

17 years of experience
252 reviews
Nathan
17 years of experience
Mitsubishi Eclipse - Front Crankshaft Seal - Buda, Texas
Nathan is incredibly knowledgeable, friendly, and incredibly efficient in his work pace. He was able to diagnose my car with ease and was super flexible in coordinating the repair to make sure everything he could do got done. 10/10 will look to him for repairs in the future

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