Skip the auto shop - Our mechanics make house calls

Symptoms of a Bad or Failing Front Output Shaft Oil Seal

output shaft oil seal

The front output shaft seal is an oil seal that is installed on the front of transfer cases. As its name implies, the front output shaft seal is responsible for sealing the front output shaft of the transfer case, keeping the gear oil or transmission fluid inside of the unit. The seal is usually round in shape, and made of rubber and sometimes metal, not unlike many other automotive engine and transmission seals. Over time the rubber can dry up and the seal can wear out, which can lead to leaks and other issues. Usually a bad or failing front output shaft seal will produce a few symptoms that can alert the driver of a potential issue.

Fluid leaking from the transfer case

The most absolute most common symptom of a problem with a front output shaft seal is fluid leaking from the front of the transfer case. If the rubber transfer case seals dry out or crack they can leak gear oil or transmission fluid. A fluid leak can put the transfer case at risk of suffering internal damage due to low lubrication. Any sort of puddles, or drips of fluid found underneath the vehicle should be addressed as soon as possible to prevent the possibility of damage occurring.

Hum, whine, or growling noise coming from the transfer case

Another symptom of a problem with a front output shaft seal is a noisy transfer case. This problem usually occurs after the seal has been leaking for a while and the fluid has run low. If the fluid runs low the vehicle may produce a hum, whine, or growling sound from the transfer case, that may be especially pronounced when the four wheel drive or all wheel drive modes are engaged. A noisy transfer case can also be caused by a number of other issues, so a proper diagnosis is highly recommended.

Like most rubber automotive seals, the front output shaft seals will eventually dry or wear out as time goes on. If you find that your front transfer case seal is leaking, or perhaps having another issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the seal should be replaced.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...

Related questions

Q: can the pcm/ecu/ecm drain the alternator

No, the alternator provides voltage to the battery and other components. The PCM could possibly discharge a battery if it leaves a relay or another circuit on, but most likely is is not the cause of your alternator failure. If...

Q: my car wont go over 30mph if i press the gas it just revs up, so does this mean my transmission is gone out?

Hello there, thank you for asking about your 2002 Pontiac Firebird. It sounds like your transmission is slipping. It does not mean it needs replaced. You will need to have the transmission checked and fixed for leaks and refill transmission...

Q: White, puffy smoke from tailpipe

Hello! There may also be an internal engine issue with the valve seals, or piston rings causing the smoke; this can be verified through a compression test. To verify if the turbo is leaking, I suggest a visual inspection of...