Alright I installed a catch can today and now I have an air leak. It drives fine boost fine but at idle its rough. I have a hose coming from the crank vent nipple on the bottom of the oil filler neck to the catch can then from the catch can I have a one way check valve then to the brake booster hose. I capped the nipple on top of the oil filler neck, put a new o-ring on the oil cap and lightly greased it. Made sure I had a seal on the oil filler neck flange.

Now I know the catch can is working, after a day of driving the catch can collected about 2-3 OZ's of fluid. But I have a ruff idle. When I took of the hose that goes to the crank on the bottom of the oil filler neck and place my finger over the hose it idles fine and there isn't any leaks. When I connected it back up and took the oil filler neck off the flange and place my hand over the hole for the oil filler neck there is a vacuum leak.

So I know the catch can and related hoses are ok the oil cap and vac nipple next to it are good. What could be leaking air? The oil filler neck where it is pressed into the motor? Or could the oil pan or something related be leaking air in???

I think it has something to do with the crank/oil pan area, but I have no idea where its coming from.

Can anybody help??

This is a Series 4 turbo...



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I've never heard of someone using the brake booster line as part of a PCV system. The filler neck not being totally sealed to the middle iron shouldnt affect idle in my experience because mine doesnt seal completely. Have you tried using different sources for vac to pull out the positive crankcase vapors?

This is how I have mine setup with no catch can.

Nipple on the side of the oil filler neck has a vac line Tee'd into a line on an intake manifold with a one way check valve (manifold vac sucking only under decel).

Bottom of the oil filler neck vac line attached going to a barbed fitting tapped into the TID (always sucking)

This PCV setup helped fixed a problem with positive crankcase in the oil pan slowing the oil drain. I dont see to get much of any blowby at all.

 

I think thats what my problem might be, tapping into the brake booster line and introducing unmetered air into the system after the throttle body.

I think I'll move the vac source to the TID like you have it and try that out.

Thanks.

 

Problem solved. Hooked up the catch can to the TID and it idles fine now.

Thanks!

 

heh, i was about to post that.....

careful where you tap into vacuum sources, im also surprised it didn't pull more oil into the can due to the vacuum.