silversrtman

iTrader: (20)

Hey all. My car has been smoking on decel after running it hard for a while now. I decided to put a catch can on it to try and rectify that problem yesterday and now it smokes so bad basically all the time. It almost seems like a valve seal problem but it's done it with two sets of heads now. Stock heads the car was fine...I think. Anyone with any insight please help. I'd rather not install new valve seals and find out its something else or something dumb I'm not thinking of. I just hope it's not the rings. Thanks in advance.

jrpimp00

iTrader: (17)

Could be rings. Also check your catch can routing

Darth_V8r

iTrader: (4)

if it got worse with the catch can install, you probably should check the routing of the hoses and make sure you have vacuum pulling through the crankcase and all that. you might also have it routed perfectly with a blocked hose or a gaping hole in a hose.

typically, worn rings will also show in a compression test, so you could check your compression as a quick and dirty. Test it and then put a squirt of oil in and test it again. if it comes up significantly - like 30-psi - that is telling you rings. if it's the same before and after the oil, rings are probably ok.

EnergyCC

Thats some good info there!

silversrtman

iTrader: (20)

thanks for the info guys. I have my can routed exactly like this diagram except I took out the PCV valve, I figured with the catch can I wouldnt need it. I will have to do a leakdown test I guess. I also read somewhere that oil could bleed down throught the rocker arm bolts with ported heads. However that doesnt explain why it got way worse after the can install.

Darth_V8r

iTrader: (4)

Is there a check valve between in the vacuum line between the catch can and the throttle?

jrpimp00

iTrader: (17)

What can do you have? Id do a compression and leakdown on it to be safe

silversrtman

iTrader: (20)

no, didnt think it would be able to pull oil like that and I also dont understand why there is THAT much oil in the PCV system. Its smoking bad.

its a Greddy can

scotty2000ss

iTrader: (2)

What catch can are you using?

silversrtman

iTrader: (20)

greddy, theres no check valve or insides, just an open element however I see a bunch of people on here with the same cans and no one seems to have a problem.

MIGHTYMOUSE

iTrader: (59)

you cant hook the crankcase to intake vacuum without a pcv valve or a restricted orifice.

fresh air -> in. contaminated air -> out. regulated with pcv valve to intake manifold to consume

once you can visualize this you are all set.

silversrtman

iTrader: (20)

Ok so i need to put the PCV inline like it was before. That makes sense. I was under the impression that the can would do a better job than the valve because I was smoking under decel after running it hard anyway before the can install. Another question, why is the PCV system THIS dirty? Why do I have this much blow by? I didnt realize how well the PCV valve was working before I took it out. I took the lid off last night and peeked in my intake and its definitely coated and the can grabbed some oil (that wasnt getting burned) as well. I tried to get my phone to focus inside the intake but it didnt work out too well.

silversrtman

iTrader: (20)

Another question. I mounted my catch can on the drivers side next to the headlight. When I put the PCV valve back inline, where should I put it? Closer to the can or in the stock location right next to the throttle body?

MIGHTYMOUSE

iTrader: (59)

i like the pcv valve connected to the intake manifold so that it does not restrict flow TO the can, only exiting.

with no restriction (above pics) the engine has full access to crankcase fumes (and the oil in it)

as far as something different that may be happening with your engine try a compression test to make sure.

Darth_V8r

iTrader: (4)

You should consider doing a compression and leak down test to set your mind at ease. In general, there's more blow-by than you realize, but a well functioning system evacuates it so it never builds up.

I'm telling you, I had the same thing happen - my intake filled with oil from the PCV system enough to choke the car at anything beyond partial throttle. When I took the intake out, oil poured out of it. I went to the LS6-style PCV, and it made a tremendous difference AND it got rid of a bunch of hoses. Catch can is a better solution, though

Chris25

iTrader: (1)

+1 I run the LS6 valley cover with a Mike Norris catch can almost zero oil loss. The biggest pain is notching the block for the cover but even that isnt bad if your patient and take your time.