Repairing a Crankshaft Oil Leak


crankshaft pulley leakRepairing your crankshaft oil leak may be pretty easy, or very difficult.  The crankshaft in your motor exits the crankcase on the front and back of the motor so it has the potential to leak in both of those places.  The back of the crankshaft is on the transmission side of your motor. This is where the flywheel bolts on and is housed inside the transmission bellhousing.

Due to the protection from dust and debris by the flywheel and the bellhousing, the oil seal at the back of your crankshaft rarely leaks.  It’s a good thing that this seal, also called the rear main seal, rarely leaks because it is a huge pain to change.  If you’ve got a leaky rear main seal, check out our article on rear main seal replacement costs to see why it is such a pain.

On the other hand, a crankshaft oil leak at the front of your crankshaft is much more common.  At the front of your motor, the harmonic balancer bolts to the crankshaft and has a pulley incorporated into it.  The harmonic balancer is fitted to your crankshaft to reduce vibrations and is an important part of your engine.  Another important part of your engine is the belt that transfers power to accessories like your air conditioner, alternator, and power steering pump.

A crankshaft oil leak is much more common at the front of your motor because the harmonic balancer doesn’t shield the oil seal as well as the larger flywheel and the front of the motor is usually subject to all sorts of road debris, salt, and grit that can deteriorate the seal over time.  Also, if your engine has a timing chain, this seal is housed in a large metal cover that can warm over time causing a leak.

When it comes to fixing a crankshaft oil seal leak the hardest part is getting the harmonic balancer off.

For the harmonic balancer to do its job it needs to be pressed onto the crankshaft so there is no room for play.  Press fits are always difficult to disassembly so you will need a harmonic balancer puller or universal puller to remove it.  Be careful not to pull outside of the rubber junction between the balancer and the pulley or you will damage the harmonic balancer.

Once you’ve got the harmonic balancer off it’s a quick in and out with the seal.  If you’ve got a frozen harmonic balancer, consider using BlueDevil Oil Stop leak to repair the front crankshaft oil leak in your vehicle and keep it on the road!

You can pick up BlueDevil Oil Stop leak at one of your local auto parts stores like:

  • AutoZone
  • Advance Auto Parts
  • CarQuest Auto Parts
  • NAPA Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys
  • Canadian Tire
  • Walmart

Photo by Chad Kirchoff on Unsplash

BlueDevil Products can be found on or at AutoZone, Advance Auto Parts, O’Reilly Auto Parts, NAPA, and other major auto parts retailers.

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