Regarding Catch Cans

[XfireZ51]

Earlier last week I happened to be looking at the catch can I installed last year. Underneath it I noticed what looked like an oily looking area. I reached under the can and felt an oil film that looked like it originated from one of the site tube fittings. So I removed the can from the car to use some plumbing tape to seal it. The can also has a bottom lid that screws into the can and I noticed it was not torqued. At this point I was pretty certain this may also be causing a vacuum
leak to the manifold. Although the motor idles well, I had noticed some slight surging at idle. More so when freewheeling while decelerating from speed. I made sure I sealed and tightened things down reinstalling the can. Actually my catch can is an oil separator and does not use any medium to trap the oil. Oil drops out of suspension as the air cools and oil collects at the bottom. Had 1-2 tablespoons of oil after 1500 miles. I can also tell there's less oil in exhaust because tips stay much cleaner and clean up much easier than before.
Took car out yesterday to a C&C. I immediately noticed how much smoother the idle was and how much less the motor oscillated when freewheeling.
The leak wasn't enough to be OBVIOUS but once tightened down, the difference was very noticeable.

[Karl]

Same thing happened to mine. The John Guest fittings began to leak so I plugged and sealed them up.

[Paul Workman]

Hmmmmm....

Veddy Intorestink!

[bradley]

what catch can do you guys use . I want to get one

[Dynomite]

Originally Posted by bradley

what catch can do you guys use . I want to get one

Elite Engineering Oil Catch Can

[Paul Workman]

Originally Posted by bradley

what catch can do you guys use . I want to get one

I use the MOROSO, mounted in the driver's headlight well.

[Billy Mild]

What benefit does a Catch Can provide? Seems like a lot of GM guys run one.

I have never seen a catch can on a 928 or 944 Turbo unless it was a very high HP build and they were trying to prevent all sources of pre-ignition.

[Dynomite]

Originally Posted by Billy Mild

What benefit does a Catch Can provide? Seems like a lot of GM guys run one.

I have never seen a catch can on a 928 or 944 Turbo unless it was a very high HP build and they were trying to prevent all sources of pre-ignition.

Suppose to be an oil separator for the PCV system minimizing the amount of oil being sucked back into the Plenum.
The Oil Catch Can minimizes the amount of oil burned by the engine. There are other ways that oil is burned (bad valve guides, bad rings) but with the Oil Catch Can oil is not burned through the PCV system.