catch cans, crankcase pressure and pcv's


May 4, 2005
Been messing with things all week. Don't know if it's just an issue with my car or if I've actually proven something. I spent all week trying to find the vehicle application for the 1162 pcv valve. Finally figured it out and purchased one through a local parts store. They had one in stock and could not get any more. Put the 1162 in and didn't notice much of a change. Decided to install a cheap catch can to see if it would help with the pcv sucking oil, it did drastically. One thing I noticed once the car was up to temp at idle, the driver side valve cover breather was still puffing some smoke?????

Decided to pull the 1162 valve and install the original gm one. Blew through both of them and noticed the original flows a lot more air to the intake side. Started the car and let it idle for a bit, no more smoke out the driver side breather. My finding is the 1162 wasn't pulling enough vacuum from the crankcase to relive the pressure. Took the car out for about 20 minutes and did 5 boost pulls (23psi) and cruised around town for a bit. Came back home and had about a 1/8 inch of oil in the small harbor freight separator I installed. Still no smoke from the breather and much less smoke on start up. I don't have a check valve installed between tb and the catch can yet, but it's good up to 150psi so it shouldn't be too big of a problem.
I also run an in line oil separater with no check valve, no smoke, my problem is finding a valve that positivly seals. I tried just running K and N breathers on both valve covers and after 2 blocks of driving in the neighborhood the smoke started. Im still waiting on the kirbans $7 pcv valve, hopefully that one seals.
I haven't figured out what I'm going to do yet. I'd like to get a check valve to start off with. Don't know if it's gonna affect the intake flow to the pcv though. The catch can is definitely a good idea. I may eventually put a good one in but this is better than nothing for now.
This is what I ended up doing. Seems like it worked. Got tired of the driver side breather dripping oil. After some investigating, I figured out what was happening. Oil was getting pushed through the tube during boost from blow by. What I ended up doing was making the hole in the breather larger and I stuffed a piece of foam through the hole, inside the breather itself. Drove it across town and back on thanksgiving, even some good boost to it, no drips. Everything is dry, the catch can is working. I get a bit of a smell once in a great while but for the most part my car doesn't stink like burnt oil anymore so I'm happy. I'm sure an angled fill tube would cure the oil dripping from the breather, but for 5 bucks this was a cheap fix. SO for about 30 dollars total I have no more oil entering the intake and no more dripping valve cover breathers. BTW, It is possible to run a large push-in breather on the passenger side like on the driver side. I wedged a small piece of pipe in the factory breather and the large breather fits onto the pipe. WIth some positioning of the original breather, the big push-in breather will sit up and not have to worry about it leaking oil. I left the baffle inside the original breather and pulled out the rest of it. It acts like a trap and doesn't allow the oil to collect in the breather.

If anyone plans on trying what I did and has any questions I'd be more than happy to post pics.
If the foam is too restrictive, it will cause an increase in crankase pressure when you have boost. Just depends upon how restrictive it is.
The foam I used was from another breather, a twist on type that was just a bit too big to fit in the valve cover. Doesn't seem to restrict flow.