PCV ( Positive Crankcase Ventilation ) Question

#1
So I'm doing some general maintenance on our new car and was changing out old vacuum lines SO when I got to the pcv and removing the grommet it come out in several pieces . I started to replace the grommet and had absolutely no luck , I found I have to order one from Kirbans for the correct size . But when I looked at our other car I found I had the pvc capped off at the valve and the vac line going to the vac block . So my question is do we have the pcv valve working or can it just be capped off ? First I have to get the grommet installed and I can see that is not gonna be any fun . Thanks Keith
 
#2
I will typically always keep the PCV connected. I really dont see the reason to delete them. Just my 02. Maybe someone will convince me otherwise but I think the folks at GM are pretty smart.
We have added open air breathers for the passenger side and drivers side so im sure that doesn't help the PCV do its job but ive had them that way almost 20 years so ni biggie.

Sent from my SM-G955U using Tapatalk
 
#3
This is another debatable topic, some builders delete the pvc completely. Others will argue that you should not. Mine was deleted when it was rebuilt 8 years ago.
Haven’t had any issues or noticed anything different not running a pvc.
 

earlbrown

runs with scissors
#5
The ECM is expecting that metered vacuum leak and it sets the fueling accordingly. Plugging that up could potentially put the INT/BLMs out of range.
 
#6
The ECM is expecting that metered vacuum leak and it sets the fueling accordingly. Plugging that up could potentially put the INT/BLMs out of range.
I'm ordering the correct grommet from Kirban's , just trying this for now . My int/blm have been bouncing around , mostly running rich .
 

TurboBuRick

Moderator
Staff member
#7
There is no advantage to deleting it. The PCV deletes itself under boost. It only works in vacuum.

The pcv plays a vital role in pulling moisture and fumes out of the crankcase. Without it, the oil will get contaminated faster.
The fumes that normally get recycled through the PCV will be coming out of the valve cover breathers and roll into the cabin.
That will be your new cologne when you been out driving.

Do some research outside the board. Do a google search about PCV function.
 
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TurboBuRick

Moderator
Staff member
#8
The ECM is expecting that metered vacuum leak and it sets the fueling accordingly. Plugging that up could potentially put the INT/BLMs out of range.
Strangely enough the chip guys never ask if the tube from the valve cover to the turbo inlet is being used. You would not believe the difference that makes in idle blm's. It's crazy. With tube in place the air that the PCV pulls in is metered by the MAF. Without the tube, it's pull unmetered air from the vc breathers resulting in a huge spike in idle blm. If anything, plugging the pcv will prolly put blm's closer in range maybe even a little low.

Just my $.02
 

RUQWKNF

KEEPER OF SECRETS
Staff member
#10
Good stuff guys.
For years, we either deleted it, or ran the brass check valve with the PCV so you won't be sucking any oil into the t-body or plenum when you're in vacuum/non boost conditions. To me, using the stock rattle ball style valve without the check valve, is the best way to contaminate the upper half of the engine with oil. IE: If you're running both valve cover breathers and a fresh cleaned intercooler with a new turbo. Aka, no other source of oil contamination coating the t-body, upper plenum and intake.

I currently run a oil catch can from both valve covers and have the PCV vented to atmosphere. My INT and BLM numbers are steady with zero fumes inside the cabin when cruising.

When I first got this car and drove it home from Cincinnati, it had both valve cover breathers and the PCV vented to atmosphere. Half way into the trip, it almost killed me from the oil fumes inside the cabin. The catch can cured that issue.
Different strokes for different folks though, so YRMV.
:cool:

-Patrick-
 

earlbrown

runs with scissors
#11
Strangely enough the chip guys never ask if the tube from the valve cover to the turbo inlet is being used. You would not believe the difference that makes in idle blm's.
I kinda want to assume that chip burners assume that tube is gone. The negatives of keeping that automatic intercooler oiler is just to great.
 
#12
Different strokes for different folks though, so YRMV.
:cool:

-Patrick-
I don't think this topic is one of those that's really up for debate. Everybody can have an opinion, but the facts are pretty clear. There's no drawback to a properly functioning PCV system, only positives. And the positives are huge.
 
#17
Good stuff guys.
For years, we either deleted it, or ran the brass check valve with the PCV so you won't be sucking any oil into the t-body or plenum when you're in vacuum/non boost conditions. To me, using the stock rattle ball style valve without the check valve, is the best way to contaminate the upper half of the engine with oil. IE: If you're running both valve cover breathers and a fresh cleaned intercooler with a new turbo. Aka, no other source of oil contamination coating the t-body, upper plenum and intake.

I currently run a oil catch can from both valve covers and have the PCV vented to atmosphere. My INT and BLM numbers are steady with zero fumes inside the cabin when cruising.

When I first got this car and drove it home from Cincinnati, it had both valve cover breathers and the PCV vented to atmosphere. Half way into the trip, it almost killed me from the oil fumes inside the cabin. The catch can cured that issue.
Different strokes for different folks though, so YRMV.
:cool:

-Patrick-

Looking at going this route myself. Do you have any pictures of your setup that you don’t mind sharing?
 

cruzn57

Still plays with cars!
#18
to add some fuel to the fire.
in the old days pre 1960, cars had a road draft tube, that vented the crankcase, and allowed fumes, blow by, to exit the engine bay,
in 1961 car manufactures added PCV ( positive crankcase ventilation ) in an effort to stop oil leaks from internal pressures of the engine, also to stop nasty smells inside the cars,
your engine IS an air pump, the rings hopefully control the blow by , (all cars have blow by) oil/gas/ combustion all slip past the rings into the crank case, it has to go somewhere, a vent (breather) is ok, but PCV positively draws fumes from the crank case at idle,
at higher rpm, the blow by is to great for a pcv to correctly handle the fumes, plus the vacuum is absent, so it doesn't work then avyhow,
not having pcv , does contribute to oil leaks, as the internal pressures from blow by have to go somewhere, your engine is like a balloon , filled with fumes, yes the vents allow some but not all fumes to exit, add the weak point , gasket, seal, etc and you have oil leaks,
we all have heard of "pan evacuation " system they work on race cars, but as soon as you add an exhaust system (muffler, tail pipes, etc) they do not work, as they rely on exhaust flowing past the pan evac tube to draw fumes fumes from the engine,
in testing various systems and designs (when I worked at Hooker Headers) we found pan evac system do not work with mufflers,etc.
I'm sure someone has gotten them to work with exhaust, but how well?