oil on crank pulley (why?)

Mark B. White

Registered User
Well my sc is pretty much all stock but well maintained. I do beat it up pretty good but I'm always on time with oil changes(mobil 5/30). It has 94,000 miles on it and today I noticed there was a pretty good amount of oil on the inside of the crank pulley. Why is this oil here, could it be a bad front main seal? Could it be a bad pcv valve (it's never been changed)? The motor still seems to run good, it is still hitting the same amount of boost and keeping the same amount of vacuum and my stock oil pressure gauge still shows really good oil pressure. Whats wrong? please help!!!
 
Get on the ground and inspect that pulley much more closely.

Start with the engine running, and use a flashlight to look at the rotation of the pulley. Is it wobbling? If so, see BELOW.

Then, with the engine off, inspect the harmonic balancer retention bolt which is attached to the end of the crankshaft. Make sure it's still there, and that it's tight. If it's not tight, see BELOW.

Then check the bolts for the pulley attached to the balancer to make sure they are tight.

If the harmonic balancer is pulling away from the engine, the front seal could begin to leak as the front seal, seals against the hub of the harmonic balancer.

If everything looks o.k., I wouldn't be surprised if the oil is just running down from a valve cover.

BELOW

Our cars have what many people would consider a defective design in the harmonic balancer. It is an interference fit on the crankshaft, but is made out of sufficiently soft material that as the rubber in the balancer deteriorates engine vibrations can distort the hub. This distortion allows the unit to start to walk off the end of the crankshaft, typically breaking the retaining bolt leaving part of the bolt in the end of the crankshaft. Options are to replace with a stock unit, or the single aftermarket alternative. The stock unit is the same questionable design of what you have right now.

You can search the forum for "harmonic balancer" and find many a saga of failed units.
 
Probably the front seal. This might be a good time to check for any wobble in the balancer (and a loose balancer bolt). If you find it is the seal, it is a fairly easy fix. Just be aware that you can't reinstall the old balancer again. (if you do, it will break sometime when you least expect it, 200 miles from home, in the middle of nowhere, in the dark, when it's raining)

Another possibility is a leak from the valve covers...they are notorius for leaking. Just snug them down with a socket and swivel extentions.......
 
Yes, I can attest to the broken balancer; even after replacing the crank bolt when I did my seal. The other notorious leak in that area is not only the valve covers, but check the hoses from the power steering pump that run under the sump pan.
 
Design flaw

Mike,

Does your comment "Our cars have what many people would consider a defective design in the harmonic balancer" include the 94-95 models or just 89-93?

Thanks.
 
If you are getting oil on the INSIDE of the main pulley, it is probably coming from the keyway in the Damper. The keyway is normally sealed using a small amount of RTV, but it is behind the washer so you won't be able to see it. Replace the bolt and washer if you remove them. Clean the area real well and fill the keyway with RTV, reinstall the bolt and washer, torque to 100ft-lbs.

All years have the same basic design - junk. If you remove the damper to change the front seal, replace it or you could be sorry later on.

Aaron
 
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