I tried searching but couldn't find anything on the pcv system on here. I was looking at the service manual, and have a question about the pcv valve and system. If I remove the pcv valve, plug the hole in the manifold and just run the valvecover vents to a catch can will I be ok or is the pcv system metered and will it be venting off measured air? I already have a maf to turbo pipe with all the holes plugged. Where I live we don't have emissions testing and I would prefer not to vent air mixed with oil back into my intake manifold.

 

Thank you

Assuming you don't care about hurting the engine internals or are planning to change your oil every 500 miles it should be fine. The PCV is only indirectly related to emissions. It's primary function is to remove acidic blow-by gasses from your crankcase. Valve cover vents will not accomplish this as there is no positive flow.

 

GD

Even tho my engine is being rebuild as we speak, I figured there will still be a small amount of blowby that would force the gasses out of the head vent. Guess I was wrong. Does the ea82t even have a crankcase vent? I swear the pcv system I saw ran from the pcv valve and connected it to the drivers side valvecover vent then connected that into the maf to turbo rubber pipe.

 

Thank you for your input

there's a tree under the intake hose i believe, at least on XT's there is, it i would guess is the crankcase vent.

 

aren't the valve covers also a crank case vent? the valve covers have wide open access through the bottom of the heads to the crank case....that's how the oil gets back to the engine?

 

i never knew the PCV system had anything to do with removing acidic by products.

 

does it matters, it's an EA82T, how much longer do you give it GD?

oh, and welcome aboard Hanover, PA - i'm from Westminster, MD but actually grew up just across the line not far from the Hanover water supply reservoir, Longarm. still go back there often.

I knew the ea82 jokes would be coming soon. Well the ea82t made it 135,000 miles the first time so I would expect the same if not more. If the crankcase vents out of the valvecover vents I am still trying to figure out why I would need vacuum from the engine to pull the oily air out. The crankcase would be pressurized right?

oh, and welcome aboard Hanover, PA - i'm from Westminster, MD but actually grew up just across the line not far from the Hanover water supply reservoir, Longarm. still go back there often.

 

Thank you. I work about 3 minutes from long arm and live in New Oxford. Nice to see some local people on this board.

If the crankcase vents out of the valvecover vents I am still trying to figure out why I would need vacuum from the engine to pull the oily air out. The crankcase would be pressurized right?

do a search for kingbobdole, he went with vented valve covers like you're talking about. i can't recall why, but i don't think he liked that set up and he didn't have a turbo which would probably exacerbate things.

 

i know he posted about it on the subaruxt.com forum, not sure if he ever mentioned it here, he's not on here as much.

Found it on subaruxt.com

 

Thank you!

cool, a man who knows how to use his computer and search, i like you already.

If the crankcase vents out of the valvecover vents I am still trying to figure out why I would need vacuum from the engine to pull the oily air out. The crankcase would be pressurized right?

 

The crankcase does end up with a tiny bit of pressure - but you aren't pulling IN any fresh air - there is no POSITIVE displacement present. Acidic blow-by simply displaces the "fresh" air present in the crankcase and soon becomes the only gasses present - it is absorbed into the oil and eats bearing surfaces - it will etch metal.

 

Back before the days of PCV valves, positive displacement was accomplished with a road-draft tube but that isn't passe anymore. You need a way to pull in fresh air - the piston pumping action will not do that without a valve to stop it from sucking back on the upstroke the same amount it tried to displace on the downstroke. The PCV valve is the solution - it's clean and simple.

 

It's important to note that there will be no PCV action durring boost - when the manifold pressure goes positive the valve slams shut and for the time that the engine is under boost it does not function.

 

GD

Now I understand. Thank you for breaking it down for me. The pcv valve in boost was going to be my next question but you already nailed it.

 

Grant