I'm trying to engineer a pcv system that works, and put it in the GN1 valve cover. One theory I have is that I have too much vacuum, thus causing oil to be pulled into the intake. My question is, does the stock pcv meter the amount of vacuum, or is it just open/ closed? I'm thinking a slight reduction in the amount of vacuum pulled on the valve cover might help reduce the amount of oil pulled in. Maybe 2 pcv's would create more "restriction", for lack of a better term.
Does the pcv have a metering device?
- Thread starter turbosam6
- Start date
I think you have the right idea....the PCV "needle" cracks open with very very little vacuum. I thought I might add a bit of weight to the needle but gave up that idea when I saw how little it takes to crack open.
I tried to contact an AC engineer to get an idea of basic principles etc...no luck...AC Customer Service stopped me!! I have an engineer friend at Ford....he tried to get some of their PCV designers to help me....no luck there either.
I know this...I had no oil residue in my intake for 7 years even though I had upgraded tp 50's, PT51, THDP, V4, etc)....but over last winter I ported my heads and went to TE62. 500 miles later and I found oil puddled in intake plenum...not from up-pipe...from PCV.
Can't be coming up PCV valve under boost so must be from vacuum....thought a bit more restriction at PCV valve would be OK.
But no luck so far....
Any other ideas....other than the catch can products??
Bob
5
I tried to contact an AC engineer to get an idea of basic principles etc...no luck...AC Customer Service stopped me!! I have an engineer friend at Ford....he tried to get some of their PCV designers to help me....no luck there either.
I know this...I had no oil residue in my intake for 7 years even though I had upgraded tp 50's, PT51, THDP, V4, etc)....but over last winter I ported my heads and went to TE62. 500 miles later and I found oil puddled in intake plenum...not from up-pipe...from PCV.
Can't be coming up PCV valve under boost so must be from vacuum....thought a bit more restriction at PCV valve would be OK.
But no luck so far....
Any other ideas....other than the catch can products??
Bob
5
I've spent hours searching this site and others trying to find a cure for the pcv problem. My last "built" motor never had this problem, although it had a valley pan gasket.
I did try something today. I relocated the pcv into the driver side valve cover, GN1 vc, btw, and with roller rockers, no oil really hits the hole. Just vapors. I bought a grommet for the vc, and put a pcv in there (unknown pcv, just fit the grommet), then put a clear fuel filter in line, then the stock pcv, then a hose going to the plenum. It worked way better than my last system, which was a pcv in the stock location with no valley pan, and a catch can. It fouled the plugs after a few miles, not good. I just got done driving it around to see how it worked. I still have some oil in the plenum, but the filter has no standing oil in it, just a coating on the walls from the vapor. There may be one or two "drops" of oil in it, but nothing like my last experiment. I always have blue smoke at idle, thanks to my wonderful GN1 heads and their sh!tty valve guides. But it got rid of the smoke I was getting out of the breathers with the pcv blocked. Now I have this setup, with a breather in the pass. side vc, and a breather in the stock pcv location. I may put a baffle inside the vc, but I don't think it will change anything. I'm not getting any liquid oil, since I have T&D rockers, which don't project oil upwards like stockers do. Other than oil on the backside of the throttle blade, I wouldn't notice the oil if it weren't for the power plate. It collects on there.
My next experiment is to put a breather style pcv thing in there in place of the unknown pcv I have now. It looks like the stock breather thing on the stock pass. side vc, but has a foam element inside to stop oil vapors. I found this at autozone, one end fits into the vc, the other will go to a stock pcv valve, then to the plenum. My concern is that it will become saturated with oil very fast, basically becoming clogged. Any ideas?
I did try something today. I relocated the pcv into the driver side valve cover, GN1 vc, btw, and with roller rockers, no oil really hits the hole. Just vapors. I bought a grommet for the vc, and put a pcv in there (unknown pcv, just fit the grommet), then put a clear fuel filter in line, then the stock pcv, then a hose going to the plenum. It worked way better than my last system, which was a pcv in the stock location with no valley pan, and a catch can. It fouled the plugs after a few miles, not good. I just got done driving it around to see how it worked. I still have some oil in the plenum, but the filter has no standing oil in it, just a coating on the walls from the vapor. There may be one or two "drops" of oil in it, but nothing like my last experiment. I always have blue smoke at idle, thanks to my wonderful GN1 heads and their sh!tty valve guides. But it got rid of the smoke I was getting out of the breathers with the pcv blocked. Now I have this setup, with a breather in the pass. side vc, and a breather in the stock pcv location. I may put a baffle inside the vc, but I don't think it will change anything. I'm not getting any liquid oil, since I have T&D rockers, which don't project oil upwards like stockers do. Other than oil on the backside of the throttle blade, I wouldn't notice the oil if it weren't for the power plate. It collects on there.
My next experiment is to put a breather style pcv thing in there in place of the unknown pcv I have now. It looks like the stock breather thing on the stock pass. side vc, but has a foam element inside to stop oil vapors. I found this at autozone, one end fits into the vc, the other will go to a stock pcv valve, then to the plenum. My concern is that it will become saturated with oil very fast, basically becoming clogged. Any ideas?
I think it is the increased vacuum that is the culprit. As I said, my thought was to counteract it via a bit more weight on the needle. I'm gonna check around at work and see if we have equipment that can detect the amount of vaccum it takes to lift the needle....very small amount. Might also destroy one to get needle weight...which would give me an idea of how much weight to add.
Seems like if one had a handful of various PCV's we could find one that withstands a bit more vacuum. I'd think that they are sized for different vacuum's produced by different engines.
If I find some portable equipment I could take it to AutoZone and just go thru their PCV's.
Bob
Seems like if one had a handful of various PCV's we could find one that withstands a bit more vacuum. I'd think that they are sized for different vacuum's produced by different engines.
If I find some portable equipment I could take it to AutoZone and just go thru their PCV's.
Bob
I understand what you're saying here, but with all due respect, I think you may be kinda backwards. If you make the needle heavier, it will take more vacuum to open it, correct? If increased vacuum is the cause, we need to decrease it somehow. Lets say for arguments sake your engine pulls 15 inches of hg. The stock pcv opens at next to no vacuum. Lets say you increase the needle weight until it takes 10 inches hg to open. Your engine will still pull it open, and the full 15 inches will be pulled on the crankcase. Does that make sense?
I commend your efforts, we need to have more people trying to fix this. I read an article over at ls1.com where a guy said he solved his oil ingestion problem by adding fuel filters in line. I think he's either done one of two things: Either he created such a restriction that it doesn't suck hard enough to do anything, or he has yet to clog the filters with oil, rendering them useless.
Maybe a vacuum regulator to reduce the amount of vacuum being pulled? Or maybe just some kind of separator.
I commend your efforts, we need to have more people trying to fix this. I read an article over at ls1.com where a guy said he solved his oil ingestion problem by adding fuel filters in line. I think he's either done one of two things: Either he created such a restriction that it doesn't suck hard enough to do anything, or he has yet to clog the filters with oil, rendering them useless.
Maybe a vacuum regulator to reduce the amount of vacuum being pulled? Or maybe just some kind of separator.
Well, me being kinda backwards part sure makes sense....I get called that 2-3 times per week...lol. I've always attributed it to the year I spent at Rantoul in the USAF long ago 
I work with a PhD fluid dynamicist...let me see if I have time to talk with him tomorrow.
I had already spoke with an Aeronautical Engineer (another PhD work aquaintance) who thought I was on the right track...he even suggested an orifice in the PCV line might be a solution....but we don't know how to size it.
Will advise.
Bob
I work with a PhD fluid dynamicist...let me see if I have time to talk with him tomorrow.
I had already spoke with an Aeronautical Engineer (another PhD work aquaintance) who thought I was on the right track...he even suggested an orifice in the PCV line might be a solution....but we don't know how to size it.
Will advise.
Bob
An orifice would definitely drop the vacuum, I was actually thinking about trying to splice in a smaller section of hose to acheive the same results, essentially a restriction.
A year in Rantoul?!?! You're lucky you can still read! Hope you didn't drink the water. We call it Rantucky here.
That town really went to hell after they closed the base. I went up there to do some scca solo racing, its like a ghost town on base. They sold out some of the living quarters, but theres a lot of empty hangars and medical buildings. They do a wicked haunted house up there though!
A year in Rantoul?!?! You're lucky you can still read!
Hope you didn't drink the water. We call it Rantucky here. That town really went to hell after they closed the base. I went up there to do some scca solo racing, its like a ghost town on base. They sold out some of the living quarters, but theres a lot of empty hangars and medical buildings. They do a wicked haunted house up there though!
Damn...I did drink some water while there....that explains a lot of things Visited there a couple of years ago....eerie feeling driving around, parking where ever I felt, not having a hat on outside, not driving 25MPH max, etc. Felt like it was still an AFB but with no cops Had a definite feeling of being controlled at all times...like we were while in military.
They have a pretty cool museum on "base" and even found the control tower cab outside behind it....it used to be on top of the main hanger.
If we meet, remind me to tell you about the New Year's Eve party I attended in Champaign...12/31/70. I'd never write it down so has to be face to face Too bizzare even today!!
Bob
Visited there a couple of years ago....eerie feeling driving around, parking where ever I felt, not having a hat on outside, not driving 25MPH max, etc. Felt like it was still an AFB but with no cops Had a definite feeling of being controlled at all times...like we were while in military.They have a pretty cool museum on "base" and even found the control tower cab outside behind it....it used to be on top of the main hanger.
If we meet, remind me to tell you about the New Year's Eve party I attended in Champaign...12/31/70. I'd never write it down so has to be face to face
Too bizzare even today!!Bob
Why not? Most PCV valves will leak boost through. I've tested many, and most will leak back by just blowing through it.
A pcv valve is designed to meter the air recovered from the crankcase in proportion to engine vacuum. If it didn't, more vapor would be recovered at high vacuum than it would at lower vacuum. They don't really "crack" open like a check valve would.
One suggestion would be to try different PCV valves if you are trying to find one that meters less vapor. However, I don't think that would really be productive. I really don't know how they determine the size of the valve, but it certainly has to do with the displacment of the motor/crankcase. Restricting the amount of "vaccum" that the valve sees may actually increase the amount of vapor it recovers because it will actually increase its metering size. As the vacuum drops, it opens more too keep the flow consistent. And, if you don't meter enough vapor through the PCV system it will only back up through the breather (crankcase inlet) on the other side.
The best suggestion I have is to 1) add a low cracking pressure check valve inline with the PCV. 2) use baffles to help keep the oil vapor from reaching the PCV valve itself. The valley pan did an excellent job of this originally, so maybe some sort of baffle, or baffle chamber before or after the PCV would be helpful. Some place for the vapor to expand and slow down allowing the oil to fall out of suspension and drain back. Even if it was after the PCV valve it could allow the oil to drain back through the valve when there was no flow (engine off). The valve covers are a highly oil saturated area, with oil flying off the rockers and valve springs. Even so in the valley, but the valley pan created a space for the vapor that was relatively stable.
On one end or the other is the metering orfice.
The size of it and the weight of the slug vary by application.
Take a 3/8" bolt and cut it off so it's like 3/8" long and drill a 1/8 hole in it makes for a good restriction, if you don't have much in the way of blow by but you might have to reset the min idle setting.
I have some Mopar PCV that on engine side has a 1/8" pipe thread. So it screws into my manifold. I also have a zero cracking check valve in line with it so no boost can lead past it.
Having 6" of hose running vertical out of the PCV valves sorta acts like an oil vapor/ air seperator.
The size of it and the weight of the slug vary by application.
Take a 3/8" bolt and cut it off so it's like 3/8" long and drill a 1/8 hole in it makes for a good restriction, if you don't have much in the way of blow by but you might have to reset the min idle setting.
I have some Mopar PCV that on engine side has a 1/8" pipe thread. So it screws into my manifold. I also have a zero cracking check valve in line with it so no boost can lead past it.
Having 6" of hose running vertical out of the PCV valves sorta acts like an oil vapor/ air seperator.
The Radius Kid
Active Member
- Joined
- Jan 26, 2002
We discussed this on Cotton's board a while back.
You might want to look here:
www.cottonsperformance.com/phpBB2/viewtopic.php?t=566
I think that'll work.
The topic is "Help my car stop smoking" in general tech.
You might want to look here:
www.cottonsperformance.com/phpBB2/viewtopic.php?t=566
I think that'll work.
The topic is "Help my car stop smoking" in general tech.
Oil is like Salmon. It goes everywhere you don't want it.
Sorry, right track on wrong car. Your right with that, the oil in just the intake (EDIT: UNDER BOOST) couldn't be from the PCV as was pointed out the flow is the opposite direction. My mind slipped to other PCV discussions I've had with oil coming from the breather. And just when it sounded like I knew what I was saying
My oil in the intake is coming from the PCV valve....no doubt about that....but because under boost it has 20 psi on top of it I don't think the oil is coming up the hose when under WOT/boost.
My oil in intake problem began exactly at the same time I went to ported heads and TE 62. I had already been at a TA49 and then PT51 turbo with no oiling problem, and I can't see how a turbo operation would drive oil up the PCV so I think it boils down to ported heads which means more flow/vacuum.
I think the key to fix it is with the PCV valve...as Bruce points out above ...there are different sizes for different applications. Changing the air flow characterisitcs with ported heads means a different PCV valve is required....which one is the key.
I'm going to try to contact a Ford PCV designers again...hope they know what they are doing instead of looking up air flow tables and picking the PCV.
Question: What is the result if there were no PCV valve circuit, or it was plugged...wouldn't crankcase vapors just come out at the valve cover breathers??
Bob
My oil in intake problem began exactly at the same time I went to ported heads and TE 62. I had already been at a TA49 and then PT51 turbo with no oiling problem, and I can't see how a turbo operation would drive oil up the PCV so I think it boils down to ported heads which means more flow/vacuum.
I think the key to fix it is with the PCV valve...as Bruce points out above ...there are different sizes for different applications. Changing the air flow characterisitcs with ported heads means a different PCV valve is required....which one is the key.
I'm going to try to contact a Ford PCV designers again...hope they know what they are doing instead of looking up air flow tables and picking the PCV.
Question: What is the result if there were no PCV valve circuit, or it was plugged...wouldn't crankcase vapors just come out at the valve cover breathers??
Bob
Bob, eliminating the pcv altogether is a bad idea. I've done it, and started getting rust on the underside of the fill spout cap. Yes the breathers will allow blowby to flow out but without the steady flow of air through the block the volatile vapors (water and gasoline) won't get swept out of the oil. Fair warning, though, this is a semireligious issue - lots of guys run that way and don't see any problems. I was in PA in the winter.
On another mailing list long long ago, a poster said that pcv valves are designed with a variable orifice. That way, at idle, which is basically maximum manifold vacuum (along with overrun), the flow is restricted, and at wot on a n/a engine, minimum manifold vacuum, the valve opens as far as it can so blowby is still collected and burnt. Might be interesting to scrounge up a vacuum pump, gauge, needle valve, and flow meter, and do some experiments.
On another mailing list long long ago, a poster said that pcv valves are designed with a variable orifice. That way, at idle, which is basically maximum manifold vacuum (along with overrun), the flow is restricted, and at wot on a n/a engine, minimum manifold vacuum, the valve opens as far as it can so blowby is still collected and burnt. Might be interesting to scrounge up a vacuum pump, gauge, needle valve, and flow meter, and do some experiments.
Orifice?
Hard to guess the orifice size, but think about it like this.. The PCV valve allows air from the crankcase to be sucked into the intake system. It is a "controlled" vacuum leak. If the valve is too big, it will leak too much air, and you will have a hard time getting a good idle. If it is too small, it won't let enough air flow through, and it won't purge the crankcase the way it is designed to do. Somebody, somewhere, must know the cfm, and the vacuum level, but who/where? On a car with a big cam, the idle vacuum will be low, and the valve will have to open more easily. The PCV valve must have two things, then; a spring which lets it open at the right vacuum, and an orifice which puts the flow in the right range. Should be fairly easy to make an adjustable one, but how would you know when it's the right size?
Hard to guess the orifice size, but think about it like this.. The PCV valve allows air from the crankcase to be sucked into the intake system. It is a "controlled" vacuum leak. If the valve is too big, it will leak too much air, and you will have a hard time getting a good idle. If it is too small, it won't let enough air flow through, and it won't purge the crankcase the way it is designed to do. Somebody, somewhere, must know the cfm, and the vacuum level, but who/where? On a car with a big cam, the idle vacuum will be low, and the valve will have to open more easily. The PCV valve must have two things, then; a spring which lets it open at the right vacuum, and an orifice which puts the flow in the right range. Should be fairly easy to make an adjustable one, but how would you know when it's the right size?
So far all I've seen as a "solution" is a catch can of some sort...and it seems that everybody is having the smae problem...n/a guys too.
I've had no luck at work finding low flow/pressure measuring equipment
I sure hope I can talk with a knowledgable PCV engineer in order to determine what they consider in design. I think we are on the right track but would hate to try to reinvent the wheel.
Anybody have a connection in this area??
Bob
I've had no luck at work finding low flow/pressure measuring equipment
I sure hope I can talk with a knowledgable PCV engineer in order to determine what they consider in design. I think we are on the right track but would hate to try to reinvent the wheel.
Anybody have a connection in this area??
Bob
PCV trouble
The trouble with pcv is there will always be oil going threw the valve no mater what,weather it be vapor or liquid some will go thigh the valve. now if you take a built motor it makes this worse. My experience with this has to do with blowby and valve placement as to how bad the oil moves. Americans built engines all have pcv trouble of some kind due to blowby. I once left the oil cap off of an BMW inline 6 and it would barely idle,Ive never ever seen A american car that was built that tight. The oly solution is to not run a pcv vent to the atmosphere or try to run a separator which over time will oil up.
The trouble with pcv is there will always be oil going threw the valve no mater what,weather it be vapor or liquid some will go thigh the valve. now if you take a built motor it makes this worse. My experience with this has to do with blowby and valve placement as to how bad the oil moves. Americans built engines all have pcv trouble of some kind due to blowby. I once left the oil cap off of an BMW inline 6 and it would barely idle,Ive never ever seen A american car that was built that tight. The oly solution is to not run a pcv vent to the atmosphere or try to run a separator which over time will oil up.
If your having oil in the PCV line problems,
then you need to make a small, oil vapor/ air seperator.
Take a pint paint can.
About 1/3 the way up from the bottom solder in a rt angle 3/8 hose fitting, then at about the 2/3 mark solder in a second one.
Fill the can Loosely with coarse Stainless Steel Wool.
Install cap, and route the PCV line in to the lower hose fitting, and then the top to the engine. Once in a while remove can and rinse out with brake clean or carb cleaner and blow dry thoughly.
then you need to make a small, oil vapor/ air seperator.
Take a pint paint can.
About 1/3 the way up from the bottom solder in a rt angle 3/8 hose fitting, then at about the 2/3 mark solder in a second one.
Fill the can Loosely with coarse Stainless Steel Wool.
Install cap, and route the PCV line in to the lower hose fitting, and then the top to the engine. Once in a while remove can and rinse out with brake clean or carb cleaner and blow dry thoughly.
Similar threads
