• Registered: 2010-04-15
  • Posts: 15

Topic: crank shaft pulley oil leak

My 1600 dp that i just rebuilt runs great 300 mile so far, another 100 and its V adjust time. BUT there is a problem. It throws oil all over rear deck lid etc, coming from the crank shaft pulley. This motor did not do this before rebuild. I didnt see anything wrong with the pulley before re installing it. I would have thought the case would be worn before the pulley, but did think about ordering a new one and seeing how it did. It used a 1/2 qt durring this first 300 miles but I'm driving it easy right now, not much over 55 to and from work again.

  • From: City of Roses
  • Registered: 2004-03-29
  • Posts: 793

Re: crank shaft pulley oil leak

Hiya ret,

Perhaps, just perhaps, the oil slinger got installed backwards?

Mike

1970 AS Bug
1970 Bus - The Ruptured Duck
  • TomB
  • Moderator
  • Offline
  • From: Austin, TX
  • Registered: 2004-03-27
  • Posts: 1,088

Re: crank shaft pulley oil leak

As Mike says - or sometimes people forget to put on the oil slinger, not understanding what it is for. There is no seal at the pulley end of the crankshaft, just the spinning "slinger" disk to throw oil outwards into the channel where it drains back into the case. I have also heard of too much sealant clogging the drain channel from this area so the oil can't drain back, and then it must go out this end of the case.
Blow-by from rings causes gas build-up in the case, and some of these gasses exit at the pulley end of the crank. Blow-by should drop quickly as the rings seat in the cylinders, but it may be time to do a cylinder leak-down test to see if there is excess leakage past the rings. A good break-in (rev immediately to 2,000 rpm for 15-20 minutes) will seat the rings quickly as well as flooding the cam / lifters with oil while they wear-in. Without that it may take a while to seat the rings.
The other major cause of oil leakage at the pulley is poor crankcase venting from the oil filler back to the aircleaner. The slight negative pressure at the aircleaner helps pull most of the blow-by to the intake, reducing the problem at the pulley. People who change to an aftermarket aircleaner with no breather hose connection often complain of oil leakage at the pulley.

  • Registered: 2010-04-15
  • Posts: 15

Re: crank shaft pulley oil leak

MUCH THANKS!!! The crank case vent hose is back in place, after mkt air breather in in the trash and my oil leak was gone on the first trip. still has only about 350 miles on it. had a rotational thump in the back when driving, so we put in new bearings seals and new cv axles.
it was a broken bearing inner race but had the cv's on hand so just replaced it all while i was in there.

  • Registered: 2010-08-10
  • Posts: 1

Re: crank shaft pulley oil leak

The same thing happened to me. I ran my motor for a few thousand miles using a paper filter coming of the breather port on the oil filler/generator stand. At some point it started slinging oil all over from the crank shaft pulley. The paper filter had become oil soaked and didnt allow proper breathing, I modified my paper air filter to accept a breather hose and the leak stopped.