PCV Valve breather?
03-07-2006, 07:55 PM
#1
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PCV Valve breather? Would this thing replace the actual PCV valve and act like a breather at the same time?
http://www.autozone.com/servlet/UiBr...ESPE%7C%7Etrue
http://www.autozone.com/servlet/UiBr...ESPE%7C%7Etrue
03-08-2006, 09:44 AM
#2
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I made a breather for $15 by buying a new oil filler cap from Fred Beans for $5
and a universal breather filter from AutoZone for $10. Drill a 3/4" hole through the top of the cap and press the breather filter's 3/4" hose into it. The top of the breather is flat and sits about 1 3/4" above the top of the cap allowing the hood to close without hard interferance.
I'm still trying to figure if this will be worthwhile with the PCV system still hooked up, probably not good for street driving, but maybe OK for the track.
I believe the end result of all the two systems is to not build up internal pressure in the crankcase and rocker arm covers. At the track at WOT, there is not much, if any, intake manifold vacuum to pull air out of the crankcase as the pressure there increases. There's no vacuum with a breather filter either, maybe just more flow area to let the crankcase pressure vent better. When the throttle is closed at high RPM, then a high manifold vacuum is created; hence, the need for a check valve (PCV Valve), to limit the amount of air and vapors sucked into the intake. So, maybe the breather will allow more air into the system so the PCV passes more air than oil vapors,
which would condense in the intake manifold? I think it's a fairly straight rule: street cars have PCV systems, while track cars have breathers. So, what's the best setup for a street car occasionaly driven on the track? Hopefully, those with more experience and the knowledge of this matter will chime in: I'd like to learn.
and a universal breather filter from AutoZone for $10. Drill a 3/4" hole through the top of the cap and press the breather filter's 3/4" hose into it. The top of the breather is flat and sits about 1 3/4" above the top of the cap allowing the hood to close without hard interferance.
I'm still trying to figure if this will be worthwhile with the PCV system still hooked up, probably not good for street driving, but maybe OK for the track.
I believe the end result of all the two systems is to not build up internal pressure in the crankcase and rocker arm covers. At the track at WOT, there is not much, if any, intake manifold vacuum to pull air out of the crankcase as the pressure there increases. There's no vacuum with a breather filter either, maybe just more flow area to let the crankcase pressure vent better. When the throttle is closed at high RPM, then a high manifold vacuum is created; hence, the need for a check valve (PCV Valve), to limit the amount of air and vapors sucked into the intake. So, maybe the breather will allow more air into the system so the PCV passes more air than oil vapors,
which would condense in the intake manifold? I think it's a fairly straight rule: street cars have PCV systems, while track cars have breathers. So, what's the best setup for a street car occasionaly driven on the track? Hopefully, those with more experience and the knowledge of this matter will chime in: I'd like to learn.
03-08-2006, 11:08 AM
#3
Originally Posted by 2blue
I made a breather for $15 by buying a new oil filler cap from Fred Beans for $5
and a universal breather filter from AutoZone for $10. Drill a 3/4" hole through the top of the cap and press the breather filter's 3/4" hose into it. The top of the breather is flat and sits about 1 3/4" above the top of the cap allowing the hood to close without hard interferance.
I'm still trying to figure if this will be worthwhile with the PCV system still hooked up, probably not good for street driving, but maybe OK for the track.
I believe the end result of all the two systems is to not build up internal pressure in the crankcase and rocker arm covers. At the track at WOT, there is not much, if any, intake manifold vacuum to pull air out of the crankcase as the pressure there increases. There's no vacuum with a breather filter either, maybe just more flow area to let the crankcase pressure vent better. When the throttle is closed at high RPM, then a high manifold vacuum is created; hence, the need for a check valve (PCV Valve), to limit the amount of air and vapors sucked into the intake. So, maybe the breather will allow more air into the system so the PCV passes more air than oil vapors,
which would condense in the intake manifold? I think it's a fairly straight rule: street cars have PCV systems, while track cars have breathers. So, what's the best setup for a street car occasionaly driven on the track? Hopefully, those with more experience and the knowledge of this matter will chime in: I'd like to learn.
and a universal breather filter from AutoZone for $10. Drill a 3/4" hole through the top of the cap and press the breather filter's 3/4" hose into it. The top of the breather is flat and sits about 1 3/4" above the top of the cap allowing the hood to close without hard interferance.
I'm still trying to figure if this will be worthwhile with the PCV system still hooked up, probably not good for street driving, but maybe OK for the track.
I believe the end result of all the two systems is to not build up internal pressure in the crankcase and rocker arm covers. At the track at WOT, there is not much, if any, intake manifold vacuum to pull air out of the crankcase as the pressure there increases. There's no vacuum with a breather filter either, maybe just more flow area to let the crankcase pressure vent better. When the throttle is closed at high RPM, then a high manifold vacuum is created; hence, the need for a check valve (PCV Valve), to limit the amount of air and vapors sucked into the intake. So, maybe the breather will allow more air into the system so the PCV passes more air than oil vapors,
which would condense in the intake manifold? I think it's a fairly straight rule: street cars have PCV systems, while track cars have breathers. So, what's the best setup for a street car occasionaly driven on the track? Hopefully, those with more experience and the knowledge of this matter will chime in: I'd like to learn.
03-08-2006, 11:55 AM
#4
bad idea to runa breather with the pcv still on the car, think about it, you are giving air a way to get to the intake without being metered by the MAF.. this can not be a good thing. I am going to do a breather setup myself, but will be capping the entire PCV system off when I do so... removing the amw catch can and all.
03-08-2006, 02:47 PM
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Originally Posted by JL ws-6
bad idea to runa breather with the pcv still on the car, think about it, you are giving air a way to get to the intake without being metered by the MAF.. this can not be a good thing. I am going to do a breather setup myself, but will be capping the entire PCV system off when I do so... removing the amw catch can and all.
03-08-2006, 03:00 PM
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Originally Posted by GuitsBoy
Yeah, sorry forgot to mention, I capped off my intake and valve cover nipples with 5/16 caps. I also have a 5/8 breather in the back driver's side. PCV = completely removed.
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03-08-2006, 03:49 PM
#8
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Originally Posted by JL ws-6
bad idea to runa breather with the pcv still on the car, think about it, you are giving air a way to get to the intake without being metered by the MAF.. this can not be a good thing. I am going to do a breather setup myself, but will be capping the entire PCV system off when I do so... removing the amw catch can and all.
03-08-2006, 07:49 PM
#9
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So theoretically a catch can like this:
Wouldnt be a good choice because of the breather?
I wouldnt think the vacuum would be strong enough to actually pull in enough air from a small breather like that to effect anything... Any body have experiecne with this can?
Wouldnt be a good choice because of the breather?
I wouldnt think the vacuum would be strong enough to actually pull in enough air from a small breather like that to effect anything... Any body have experiecne with this can?
03-08-2006, 08:17 PM
#11
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Originally Posted by JL ws-6
If you want to use a catch can, use one like an amw, one hose goes to it from teh pcv lines, the other goes to the intake... no air breather anywhere.. the idea is for the can to catch the oil in the air that is being drawn from the engine.
03-09-2006, 02:21 AM
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Originally Posted by prostock_bigblock
Ya watch out guys , never run a breather without getting rid of the complete system, I know a guy who done that and his oil pressure is fluctuation all the time and his oil pressure dropped under 40 on idle .
That doesn't make any sense......
I understand that the PCV needs to be a closed system with a maf as the air is already metered. Any air drawn from an open breather becomes unmetered. But if you're running SD mafless that isn't an issue.
With a valve cover open air breather and closed PCV.... under normal accel. fresh air is drawn through the crank case through the valve cover breather through the PCV sys and into the intake. Under hard accels where crank case pressure rises... the flow out the open air breather can be reversed and added crankcase ventilation.
I don't see how oil pressure could fluctuate with such a system if there is a source of air from which the PCV sys can draw and not create too much vacuum in the crankcase. Now if you capped off your breathers and just ran a PCV draw, I could see the system pulling oil from the bearings.... And pushing out the dipstick under load.
03-09-2006, 03:11 AM
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That doesn't make any sense
I don't see how oil pressure could fluctuate
I beleive what I saw and what I experienced.
Thanks for the comment.
03-09-2006, 04:01 AM
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Originally Posted by prostock_bigblock
have u seen any body doin this? I did an I advised the guy to get rid of it and put the oil cap back , and everything ran normal .Asked him to put it again and the same problem appeared again , I dont know if that does make sense to u !!
I beleive what I saw and what I experienced.
Thanks for the comment.
I beleive what I saw and what I experienced.
Thanks for the comment.
One thing I did notice is when I first put a breather on the drivers side valve cover nipple (normally capped) it didn't vent and pushed up the dip stick. When I put the breather on the passenger side it vented fine under WOT and has worked for many miles. Not sure what your friend did.
Last edited by FRCstruggla; 03-09-2006 at 04:16 AM.
03-09-2006, 02:25 PM
#18
So, now i'm a little confused, I just put on a LS6 valley cover, and have the PC valve set so that under vacuum in the intake, it should close the PCV correct? Maybe I'm not udnerstanding how the vacuum works, so, when you're accelerating, it decreases because you have the throttle all the way open, so pressure is equalizing with the outside air? now the more the throttle closes, the more vacuum is being pulled because the engine now has to suck air through a small hole, which generally means less crankcase pressure, so the PCV valve closes?
Please help me if I need help!
Adrian
Please help me if I need help!
Adrian
03-09-2006, 08:16 PM
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Originally Posted by GuitsBoy
Yeah, sorry forgot to mention, I capped off my intake and valve cover nipples with 5/16 caps. I also have a 5/8 breather in the back driver's side. PCV = completely removed.
What does it take to run a breather in the drivers side cover? I have a 98. Does a 5/8 breather push right into the hole in valve cover or is there a groumet that needs to be installed first then the breather? If so where do you get this groumet and breather? On the pass. side im going to run a metco.
Thanks for any help guys.
