Is this an air/oil separator problem?

[blue2000s]

I've been experiencing a SLIGHTLY bumpy idle, like +/-50RPM. Cleaned the throttle body, no change. I disconnected the hose here and found a little coating of nice, fresh smelling Royal Purple. RP has a really distinctive smell.

Is this a sign of impending AOS failure?

[1schoir]

I've been experiencing a SLIGHTLY bumpy idle, like +/-50RPM. Cleaned the throttle body, no change. I disconnected the hose here and found a little coating of nice, fresh smelling Royal Purple. RP has a really distinctive smell.

Is this a sign of impending AOS failure?

It depends on what you mean by "a little coating".

Was there any pooling of oil in the throttle body?

Run the engine at idle and unscrew the oil fill cap. If there is a very strong vacuum that makes it difficult or almost impossible to pull the cap off, that is another sign that the AOS is failing. A slight vacuum is normal.

Regards, Maurice.

Edited March 3, 2009 by 1schoir

[blue2000s]

I've been experiencing a SLIGHTLY bumpy idle, like +/-50RPM. Cleaned the throttle body, no change. I disconnected the hose here and found a little coating of nice, fresh smelling Royal Purple. RP has a really distinctive smell.

Is this a sign of impending AOS failure?

It depends on what you mean by "a little coating".

Was there any pooling of oil in the throttle body?

Run the engine at idle and unscrew the oil fill cap. If there is a very strong vacuum that makes it difficult or almost impossible to pull the cap off, that is another sign that the AOS is failing. A slight vacuum is normal.

Regards, Maurice.

The cap comes off, there's the normal vacuum when it's removed, but it's not very strong.

[1schoir]

The cap comes off, there's the normal vacuum when it's removed, but it's not very strong.

Your AOS should be okay then, as long as you don't have more significant deposits of oil where your red circles indicate and at the throttle body.

Also check the bellows part of the AOS to make sure it's still intact. Most of the time, when it rips or tears, you will also have telltale caked coating of oil and dirt in the area.

Finally, a failing AOS usually produces prodigious amounts of white smoke that will engulf most of your entire street.

Regards, Maurice.

[por911]

I found the AOS failed on our 01 base around 40k. Symptoms were:

-lumpy or rough idle

-would not rev up easily

-excessive smoke on start-up

-lots of coking or blow-by in the crankcase breather hoses

Its just a glorified pcv for the crankcase. They are not terribly expensive and cheap insurance towards avoiding oil leaks and other issues. If the car has some miles on it(50k+), you might consider replacing it.

Regards