Foam in Engine Oil

[Silly Willy]

The other day I was doing some work on my 91 Yj's 4.0 and noticed something a little strange.

There is a strange white/yellow foam that I noticed in the valve cover and the dip stick tube. I haven't noticed it before now and want to know why its there and where its from.

The biggest concern I have about it is that it is going into the tube that goes from the valve cover to the air box and getting sucked into the engine, as well as from the valve cover to the vacuum lines.

Is there anything to worry about? Anything off the top of your heads that may be causing the foam?

 

[BCGPER]

Sounds like water is getting into the oil. Any coolant loss?

 

[jackjoh]

What BCGPER said.

 

[Caleb]

Has your YJ been sitting a long time. Sometimes condensation can build from the engine sitting without use. However, the most likely explanation is what bcgper said.

 

[jswainthug]

Water x4!

 

[MikeGyver]

Condensation. Short trips will cause this because the engine won't heat up long enough to evaporate the moisture out of the system. Also check the PCV system.

 

[UNSTUCK]

I vote condensation. Drain the oil. I bet it will look okay.

 

[Silly Willy]

There is nothing in the oil, (already drainned it) nothing in the anti freeze either, its also my daily driver 45 min each way to work 5 days a week.

Any other ideas what it would be from?

 

[cheepin]

Sounds like condensation.Like said short trips will do it.

 

[lewis]

Had the exact same issue on the 92 yj I had. I took a sample into wheeler and had them analyze it to see what it was. The only thing they found was engine oil.

 

[Silly Willy]

After hearing the solution of condensation I went and checked out the engine again. It appears that my oil fill cap had a bad seal (Was leaking some oil is what brought it to my attention) I'm pretty sure that was the culprit in this situation.

I switched out the 91 valve cover (Something I have been wanting to do for a bit now) for one from a 96 4.0 and I'm pretty sure the issue will be resolved once I change the oil again.