57 oil on #3 cylinder

[Peter Nieuwlandt]

Hi

I'm having problems with oil getting on the # 3 cylinder spark plug of my 365 engine.
As You well know these engines have the infamous vacuum pump wich sits under the oil pump and in the oil !!!!

On this engine the one way pass valve and the tube going to the wiper motor were already removed when I got it.

I've heard and read some posts about this problem and always it refers to oil on the #3 cylinder but what I would like to know before I start tearing down my engine is HOW the oil gets up to the intake manifold in order to get to the # 3 cylinder??

Thanks

Peter

[Coupe]

The line from the auxiliary vacuum pump is tee'd into the vacuum line coming from the manifold just in front of the carburetor. If the check valve for the vacuum pump fails engine vacuum will pull oil into the runner that feeds 3 and 4. When this happened to me it was quiter surprise.  I was leaving an interesection and shut down traffic until the smoke cleared.

When you talk about the one way bypass valve are you talking about the one on the firewall? If so that is after the tee to the manifold.

[Coupe]

If oil is only showing up on #3 it could be a worn valve guide and/or o-ring.