PCV with check valve

dsa87gn

Member
Joined
Sep 9, 2002
Lots of threads for and against this. Here my experience so far.

My car leaks a bit of oil out through the inspection cover hole that seems to be worse if I’m driving her hard.I bought a check valve and a spoolfool drip lip and put them in recently.

Put the valve inline with pcv, no catch can. My blm’s at idle were always on the high side 142ish. Now they are much better 125-131. Not sure how this helped but works for me.

I have put different original Delco pcv valves in before, but always struggled with the high balm. The only reason I put it in the check was I figured the 23+lbs boost was getting past the pcv and aggravating the leak.
 
So, a few things:

1) Any boost above stock will leak past the PCV and pressurize the crankcase. It's not a well built valve. You can blow through it the wrong direction with your face.
2) BLM at WOT aren't a thing, with the stock ECM, you're open loop running off a table at WOT. PCV isn't in the mix, except for the crankcase pressurization that happens
3) Your BLM's improving indicates to me you fixed a leak inadvertently when you disturbed the system to install the check valve. Good job!

Surveying the threads as a democratic exercise isn't a good idea. The PCV system is needed. It should be a closed system tied back in after the MAF with no valve cover breathers. Anything else is creating excess pollution and making your car smell like a poorly maintained service station.
 
I have the pcv with check valve plus breathers on the valve covers.

The only drawback is that when on boost, there is nothing scavenging blowby ouy of the engine...blowby must work its way out the breathers...not good.
Stock valve breather works but oils up the turbo and intercooler. Next best thing is using a vac pump with a pressure switch.
 
I have breathers on both covers too. Between this, no cat converter, & egr disabled, its like Turbo6inKY says, stinks like bad service station. My wife often comments on how bad it smells after I pull into the garage.
 
@kirbans

343596
 
"The PCV system is needed. It should be a closed system tied back in after the MAF with no valve cover breathers."

Is there any advice on best the way to do this anywhere?
 
"The PCV system is needed. It should be a closed system tied back in after the MAF with no valve cover breathers."

Is there any advice on best the way to do this anywhere?
Look up catch cans. Tons written on it. You need valve cover breathers. The factory system had one that went into the Turbo intake. This coats the intercooler with oil mist. Add catch cans and it removes the oil mist.
 
"The PCV system is needed. It should be a closed system tied back in after the MAF with no valve cover breathers."

Is there any advice on best the way to do this anywhere?

Plug your valve cover breathers and let us know how that works out..
 
Any nice options to use to plug the valve cover breathers ?

I have the Oil fill breather on the driver and small pass breather.

Do not plug the valve covers. The valve cover breathers are the only means for the crank case to relieve pressure under boost. Do not listen to anyone who tells you to plug the valve covers. That is a big no-no.
 
"The PCV system is needed. It should be a closed system tied back in after the MAF with no valve cover breathers."

Is there any advice on best the way to do this anywhere?

I wrote up what I did here:
https://www.andrewdscott.com/?p=72

It's a two-circuit system with two catch cans. The regular PCV circuit is augmented with a check valve and a catch can. Capped breathers were used on the valve covers going to another catch can, then to the intake between the turbo and the MAF.

In normal operation (vacuum), the PCV functions normally, pulling from the lifter valley, which draws metered air from the intake tube through the engine, through the catch can, then into the intake manifold to be burned. When it goes into boost, the check valve closes and the circuit on the breathers reverses. Gas is drawn through the breathers into the intake tube by the turbocharger inlet.
 
I wrote up what I did here:
https://www.andrewdscott.com/?p=72

It's a two-circuit system with two catch cans. The regular PCV circuit is augmented with a check valve and a catch can. Capped breathers were used on the valve covers going to another catch can, then to the intake between the turbo and the MAF.

In normal operation (vacuum), the PCV functions normally, pulling from the lifter valley, which draws metered air from the intake tube through the engine, through the catch can, then into the intake manifold to be burned. When it goes into boost, the check valve closes and the circuit on the breathers reverses. Gas is drawn through the breathers into the intake tube by the turbocharger inlet.

I like your set up but there is some confusion when you say CAPPED BREATHERS. It vents through the hose fitting.

You have the right idea with a stock chip but aftermarket chips (like TT or BB) are configured to run with open breathers unless otherwise specified.
That has been verified. Prior to that I thought the same way with the air metering.
 
Last edited:
I like your set up but there is some confusion when you say CAPPED BREATHERS. It vents through the hose fitting.

You have the right idea with a stock chip but aftermarket chips (like TT or BB) are configured to run with open breathers unless otherwise specified.
That has been verified. Prior to that I thought the same way with the air metering.

I observed the opposite on my car with my TurboTweak 5.7 chip. With open vents to atmosphere, my BLMs would walk up into the mid 140s within about a minute of going closed loop. As soon as I implemented my system, they were down to 130-131.

Plus I could take my girlfriend out on a date in the car and we didn't smell like gasoline.
 
I observed the opposite on my car with my TurboTweak 5.7 chip. With open vents to atmosphere, my BLMs would walk up into the mid 140s within about a minute of going closed loop. As soon as I implemented my system, they were down to 130-131.

Plus I could take my girlfriend out on a date in the car and we didn't smell like gasoline.

I hate fumes in the cabin too and I LIKE your set up but you have another problem that you masked by drawing the pcv from the meter.
Ask Eric yourself.
 
IMO Turbo6 set up is the best way to do it if you don’t still have the stock breather tube from the passenger valve cover to the turbo inlet.

Just may want to specify this when ording chips.
 
Top