Is the 'valve' on vac system a PCV valve?
09-13-2011, 03:54 PM
#16
Burning Brakes
When I rebuilt my car, I ordered everything new from the 1st posts parts picture. My car originally did not have the valve so I started to investigate why not. I searched and searched for the answer to what this valve was and why no other 951 had it here on Rennlist to no avail. BUT I came up with my own answere to this question.
I don't know if I am right or not but I have noticed how clean my motor and intercooler is.
First thing I noticed about the valve was that it opens inward to let air in. NOT OUT.
Second thing is that with the Oil/Air seporator on the 951 is nothing more than a very crude oil catch can that drains back into the motor and can pull too much oil into the intake side of the motor if the suction is too strong. Also I have noticed that the hole at the top is fairly small. Lindsey Racing has a modification for this but I do not think that it is wise to enlarge it unless you run an aftermarket catch can.
I think that Porsche in developing the 951 motor started noticing too much oil in the intake side of the motors as they aged. Their solution was to install this valve to help limit the amount of suction from the PVC line to the intake. I also noticed that they redesigned the entire hose system. See the Venturi Delete thread on this and notice how the older system would limit the vacuum to the system.
Just my input for what it is worth.
I don't know if I am right or not but I have noticed how clean my motor and intercooler is.
First thing I noticed about the valve was that it opens inward to let air in. NOT OUT.
Second thing is that with the Oil/Air seporator on the 951 is nothing more than a very crude oil catch can that drains back into the motor and can pull too much oil into the intake side of the motor if the suction is too strong. Also I have noticed that the hole at the top is fairly small. Lindsey Racing has a modification for this but I do not think that it is wise to enlarge it unless you run an aftermarket catch can.
I think that Porsche in developing the 951 motor started noticing too much oil in the intake side of the motors as they aged. Their solution was to install this valve to help limit the amount of suction from the PVC line to the intake. I also noticed that they redesigned the entire hose system. See the Venturi Delete thread on this and notice how the older system would limit the vacuum to the system.
Just my input for what it is worth.
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Dwizle (05-11-2021)
09-13-2011, 04:28 PM
#17
I would be interested to see how the valve you got looks like, as both the one I had on my stock '90 engine and the one I recently bought release pressure to the atmophere (which means letting air out) when there is pressure in the PCV line, not vacuum.
Regardless how much vacuum goes through the PCV line, it is not supposed to open, except perhaps when applying a level of vacuum high to the point of making it collapse.
Regardless how much vacuum goes through the PCV line, it is not supposed to open, except perhaps when applying a level of vacuum high to the point of making it collapse.
Last edited by Thom; 09-13-2011 at 05:45 PM.
