PCV valve is Best place to catch oil
Mar 26, 2008, 08:31 AM
#17
Good thread, there is the PVC check valve side which sends pressure, one way, into combustion only in vacuum. Then there's the ventilation side which routes the fumes into the charge downstream MAF (closed system under boost), but under vacuum pulls MAF metered air back into sump to be sent through PVC side.
I have to replace oil absorbant material on the PVC catch weekly, but the cold air side stays clean.
It's the most unusual thing, I think, is to see a layout with a catch on the ventilation side only. If you are catching oil there and the PVC check valve isn't blocked then maybe there's compression, valve, and/or blowby problems.
I have to replace oil absorbant material on the PVC catch weekly, but the cold air side stays clean.
It's the most unusual thing, I think, is to see a layout with a catch on the ventilation side only. If you are catching oil there and the PVC check valve isn't blocked then maybe there's compression, valve, and/or blowby problems.
Mar 26, 2008, 11:26 AM
#20
Account Disabled
ya ocasional oil get threw the vent side, it good idea to use a catch can to stop oil from getting into your intake tract. PCV I empty out every week. I got a really small catch can on that PCV side, thats why i empty it so often. it colect a spoon full every 3 days or so.
Mar 26, 2008, 01:40 PM
#21
Holy thread explosion.
Exactly what I was trying to tell the OP.
To the guy who said "if catch cans are so great they would have come stock":
Have you ever actually looked inside your intake pipe? If you do, see all that oil residue in there? Over time, it can get all over much more of the intake tract, including the compressor, IC pipes, and IC core. If this becomes bad enough, it can contribute to heat retention and loss of cooling efficiency, and is crap going into your engine.
Besides, how do you think the average consumer is going to react when his owners manual says "oil catch tank will fill up, this is normal. just empty it at every oil change?"
To those interested in the eBay cans, you may also want to consider this option for even less money:
https://www.evolutionm.net/forums/sh...d.php?t=255949
I KNOW the writeup doesn't address the PCV side, but it's just a reference for the can and you can use it however you please.
For a while now I kept thinking why even run pcv closed systems? We could just run two breathers and let blow by gasses vent to the atmosphere. Heck most people drive without any catalytic converters when they mod their cars, how much more damage will the pcv do...
But after doing some more searching online, I foun that it is actually pretty important in ventilating under the valve cover.
http://filtercouncil.org/techdata/tsbs/94-2R1.html
So pluging that side will stop the needed ventilation.
Here is another good read:
http://www.answers.com/topic/pcv-valve
But after doing some more searching online, I foun that it is actually pretty important in ventilating under the valve cover.
http://filtercouncil.org/techdata/tsbs/94-2R1.html
So pluging that side will stop the needed ventilation.
Here is another good read:
http://www.answers.com/topic/pcv-valve
To the guy who said "if catch cans are so great they would have come stock":
Have you ever actually looked inside your intake pipe? If you do, see all that oil residue in there? Over time, it can get all over much more of the intake tract, including the compressor, IC pipes, and IC core. If this becomes bad enough, it can contribute to heat retention and loss of cooling efficiency, and is crap going into your engine.
Besides, how do you think the average consumer is going to react when his owners manual says "oil catch tank will fill up, this is normal. just empty it at every oil change?"
To those interested in the eBay cans, you may also want to consider this option for even less money:
https://www.evolutionm.net/forums/sh...d.php?t=255949
I KNOW the writeup doesn't address the PCV side, but it's just a reference for the can and you can use it however you please.
Last edited by hokiruu; Mar 26, 2008 at 01:42 PM.
Mar 26, 2008, 03:21 PM
#23
Interesting observation about the billet aluminum ebay cans. Cold weather causes a lot of condinsation in these solid billet cans and I have found a good amount of water in them during the winter. I know it is time to drain them when suddenly there is smoke coming from my tailpipe. Scared the crap out of me the first time it happened. It turned out to be a 95% water and 5% oil being sucked right out of the can. Makes me think that I should cap the line to the intake and put a breather on the can from the valve cover instead. Someone told me to drill a whole in the top of the can and put a breather there and keep the line on the intake. Since I run a MAF I don't think that is a good idea since it would allow unmetered air into the system and potenitally lean out the tune somewhat. Probably fine for a speed density car though.
Mar 26, 2008, 03:42 PM
#24
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pcv valves do not dump back into the crankcase. they dump oil into the intake manifold. the pcv valve is closed when under heavy boost, the pcv is also closed under full vacuum. the pcv only opens when the crankcase has slight pressure to push against the internal spring, but not enough pressure to push it all the way closed. this keeps the presssure in the crankcase low so you do not push the pressure built up out all of the seals such as the front and rear main seals..... the breather will vent the crank case gases to the suction side of the turbo when there is enough pressure to block the pcv. the breather also introduces fresh air into the crankcase, so dont leave it open. use a filter or catch can
Mar 26, 2008, 03:44 PM
#25
Interesting. Good to know EvoTech, now we won't all panic and think our HGs are blown or something.
Yeah, putting a breather on the can sounds like a bad idea. Then what would be the point of having the line plumbed back into the intake tube? None that I can think of, plus the unmetered air issue you mentioned.
There were some more interesting breather setup ideas and experiences in the "discuss here" thread off of my catch tank how-to.
Yeah, putting a breather on the can sounds like a bad idea. Then what would be the point of having the line plumbed back into the intake tube? None that I can think of, plus the unmetered air issue you mentioned.
There were some more interesting breather setup ideas and experiences in the "discuss here" thread off of my catch tank how-to.
Mar 26, 2008, 03:45 PM
#26
pcv valves do not dump back into the crankcase. they dump oil into the intake manifold. the pcv valve is closed when under heavy boost, the pcv is also closed under full vacuum. the pcv only opens when the crankcase has slight pressure to push against the internal spring, but not enough pressure to push it all the way closed. this keeps the presssure in the crankcase low so you do not push the pressure built up out all of the seals such as the front and rear main seals..... the breather will vent the crank case gases to the suction side of the turbo when there is enough pressure to block the pcv. the breather also introduces fresh air into the crankcase, so dont leave it open. use a filter or catch can
Mar 26, 2008, 04:33 PM
#29
Breather on valve cover and intake pipe capped. (I think should not affect anything)
As you can see, the stock system pulls in air into the valve cover from the intake pipe. (The portion that already registered after the maf sensor) If you put a breather, then the air being pulled under the valve cover will be from the atmosphere not metered by the maf sensor. This is why it is a bad idea to run a breather, because you will be pulling unmetered air.
You want the pull in metered air to avoid idle issues, or stalling issues etc....