Valve cover vent + PCV question

[CP]

Exactly, though I'm also considering the T and one-way inline valve approach mentioned above.

 

[jepherz]

Ahh, gotcha.

 

Yeah...I should have pointed out that I no longer own a PCV Valve. Instead I own a little piece of aluminum to cover up that nasty hole left whtn the PCV was removed.

 

[powerplay]

If you are going to have a PCV and a catch can, I would put the PCV on the manifold side of the catch can, unless you want to pressurize the catch can. Of course the manifold vacuum will want to suck all of the crap out of the can as it sucks air in from the VC. You could pressurize the catch can and blow all of the snot out of it, but then you would have a boost/snot leak.

 

[Polish]

Good point Scott. Not sure how well some catch cans would hold up to 15+ psi.

 

[powerplay]

Not to well, I wouldn't think. I run the two VC lines to vented catch can, no pcv, I have no problems. I think if the catch can is puking snot all over the engine bay, then there are other issues and I wouldn't want that stuff in my intake.

 

[Polish]

Thats how I had mine for a while and it worked fine but I just didn't like the idea of all those oil vapors floating around in the crank case all the time. I noticed the oil was dirty really quickly. It also sprayed a fine mist of oil out of the breather filter out of the catch can at WOT. I could tell because after a WOT run there would be a very small film of oil behind the filter on the firewall. I just didn't like that. To each his own though. /ubbthreads/images/graemlins/smile.gif

I would rather it just go in the engine and get burned up. It can't affect performance much, if at all. Besides it will eventually have WI so that will keep everything shiny clean anyway. /ubbthreads/images/graemlins/cool.gif

 

[CP]

Quote:
I run the two VC lines to vented catch can, no pcv, I have no problems. I think if the catch can is puking snot all over the engine bay, then there are other issues and I wouldn't want that stuff in my intake.



That's how I've currently got it set up and the filter on top of my catchcan spews oil mist all over that portion of the engine bay.

 

[atc250r]

Ditch the PCV valve and put a 1/8" NPT x 3/8" hose barb fitting into the hole. Then you can run that along with a hose off of the stock breather line into a catch can or dump it onto the ground under the car. When I had a catch can it was a PITA to empty it all the time so i ran two of the fittings I mentioned above off of both the VC holes and ran a pair of 3/8" fuel hoses down between the front subframe and firewall. So little comes out of there that you won't be oiling the track down or anything. Lots of cars used to use that system and it was called a "road draft vent". That'll keep your intake nice and shiny inside.

John

 

[powerplay]

I have the 3/8" fuel line running down from the bottom drain on the catch can. I never have to empty it, because I do what John said. When I am going for a drive on the highway, I open the drain and let the air running under the car suck the crap out of the can. There is so little coming out that it is much less oil than a normal car with an oil leak. I have never seen any indication of oil on the top of the catch can. I explained that to CY over as year ago to ditch the PCV valve and set it up that way. I have left it open for months at a time, because I forget to close it, and I never see anything on the garage floor under the hose. That said I have toyed with the idea of putting a little vacuum pump on there to suck the vapors out, but the ones the V8 guys use are way to expensive for something that is OK the way it is. To each his own. I have other things to worry about driving one of these cars. /ubbthreads/images/graemlins/grin.gif

 

[CP]

I'm going to try this for a little while and see if I get any oil in the intake pipe. I put a brass barb in a soft part of my intake pipe, and attached that to an inline filter that feeds from the valve cover vent elbow. So essentially it's setup like stock with a filter:



I ran a straight fitting from the PCV valve hole in the valve cover. This goes to a sealed catchcan. I blocked the opposite hole of the catchcan. Then I ran a hose from the top of the catchcan to a fitting on the intake manfold. There's an inline plastic PCV valve in that hose:



I didn't test for any intake leaks, so I'll be interested to see if that inline PCV valve can hold boost. Any comments? This is by no means permanent, and can be modified pretty easily.

 

[atc250r]

At this point you're completely not emissions compliant anyway so I don't get why you don't just vent them both as I recommended. /ubbthreads/images/graemlins/dunno.gif It'd keep the gunk out of your intake tract and your intake manifold, plus it will eliminate any unmetered air from getting into the intake system.

John

 

[CP]

I was under the impression that venting the PCV valve (with no vac pulling it open to evacuate) doesn't help draw the crap out of the valve cover. I also thought the air coming out of the valve cover breather tube was metered air that should be routed back into the system.

 

[atc250r]

If you replace the PCV valve with a fitting, and vent everything on the VC to atmosphere then you don't have to worry about any metered or unmetered air being involved with the breather system. If you put the hoses off of the VC down near the bottom of the car, the air passing under the car will pull the fumes out of the crank case. Besides, you change your oil often so sludge won't be a problem.

John

 

[CP]

Well sh*t, all that work for nothing. I'm leaving it as is for now.

I had both vented to atmosphere before, through a filter on top of the catchcan (no PCV valve) and it made a mess out the top of the filter. I also got some nice sludgy oil/coolant sperm-looking mix in my catchcan with it setup like that. I don't want that juice blowing all over the bottom of my car. The catchcan should catch anything coming via that route, and I'm hoping the inline filter will catch anything coming out of the valve cover breather before that air goes back into the intake pipe. Everything is dry right now, and I plan to monitor frequently for oil residue. If my intake is getting greased, I'll change things.

 

[CP]

Update: My valve cover breather hose spits the funk out just ahead of the steering rack down onto the road. The other hose (with PCV valve removed) goes into a catchcan with a filter on top. This setup has resulted in the least amount of spewage from the catchcan filter, and frees up a port on the intake manifold to use for something else.