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Valve Cover Filter

A

acontour

CEG'er
Joined
Dec 14, 2007
Messages
245
Hello guys.

To all of you experts..

Is it bad to run a valve cover small filter?(valve cover breather) I have the original hose connected to a small k&n filter which bypasses the air intake. I'm trying to figure out if somehow affects the PCV system and if this is why excessive oil consumption takes place..More blow-by and that sort of a thing..

In the stock air box , the valve cover hose plugs into the air box under the filter.

Also wondering if the air being pushed out from the valve cover gets sucked with the air from the CAI will reduce blowby..

If nobody knows , I might have to figure out a way to run it back into my CAI before the filter or have an oil collector in the hose(noticed small amount of oil in the little filter..don't want to get that back into the engine) before it goes back into the intake(after filter)

Thanks for any ideas
 
I haven't looked at the Zetec PCV plumbing specifically, but most PCV systems these days are closed loop, meaning that the PCV flow is accounted for after the mass air sensor.

99% of the time, your engine intake manifold is running under some vacuum, so PCV flow will be from the air filter box (the fresh air supply), through the line to the valve cover, down through the engine, out the oil separator, through the PCV valve (if one is used), and into the intake manifold, usually through a line that attaches near the throttle body.

If you replace the oil fill cap with a breather element, the engine will now be drawing unmetered fresh air through the breather and into the PCV system. This may cause a long term lean condition, it may not, it might throw a code, it might not, a lot of folks do this with no ill effects - it depends. But... installing a breather won't keep from crapping up the intake manifold with PCV juice, in fact , it might make it worse. Fords of this era are known for having hyper-active PCV systems, but it's probably not contributing to excess oil consumption, just gunking-up of the intake.

If you're worried about crapping up the intake manifold with PCV gunk, you either need to completely disable the PCV system and install some passive breathers on the valve cover and oil separator ports, or you need to install an oil trap in the suction line between the PCV valve and the intake manifold, like I did here.
 
the valve cover port is a fresh air inlet most of the time, but when WOT it will pull a slight vacuum in the stock setup. if you want you can run an oil separator and then feed it back into the intake before the MAF.
 
The zetec PCV system draws fresh air from upstream of the MAF sensor, so replacing that hose and the little sponge filter with a small breather filter would be acceptable as it would not affect the fuel air mixture in any way. On engines that use metered air for the PCV system, this would NOT be acceptable.
 
You can put 50 breathers on there if you want, the PCV valve ITSELF is the metering device. It will only flow so much and as designed. The restriction of valve and ensuing leak is prefigured into the F/A map.
 
mcgarvey said:
The zetec PCV system draws fresh air from upstream of the MAF sensor, so replacing that hose and the little sponge filter with a small breather filter would be acceptable as it would not affect the fuel air mixture in any way. On engines that use metered air for the PCV system, this would NOT be acceptable.
Click to expand...

Yes, the Focus differs in this way, which is why those who buy Focus SRIs/CAIs have that little nipple for the breather hose AFTER the MAF on a Contour setup. This should be capped off and the separate hose and filter should be plumbed to the valve cover.
 
Uh, my Focus zetec setup is EXACTLY like the Contour one.
 
gmorrell said:
I haven't looked at the Zetec PCV plumbing specifically, but most PCV systems these days are closed loop, meaning that the PCV flow is accounted for after the mass air sensor.

99% of the time, your engine intake manifold is running under some vacuum, so PCV flow will be from the air filter box (the fresh air supply), through the line to the valve cover, down through the engine, out the oil separator, through the PCV valve (if one is used), and into the intake manifold, usually through a line that attaches near the throttle body.

If you replace the oil fill cap with a breather element, the engine will now be drawing unmetered fresh air through the breather and into the PCV system. This may cause a long term lean condition, it may not, it might throw a code, it might not, a lot of folks do this with no ill effects - it depends. But... installing a breather won't keep from crapping up the intake manifold with PCV juice, in fact , it might make it worse. Fords of this era are known for having hyper-active PCV systems, but it's probably not contributing to excess oil consumption, just gunking-up of the intake.

If you're worried about crapping up the intake manifold with PCV gunk, you either need to completely disable the PCV system and install some passive breathers on the valve cover and oil separator ports, or you need to install an oil trap in the suction line between the PCV valve and the intake manifold, like I did here.
Click to expand...

I thought the valve cover on the Zetec pushed air out instead of sucking it. I'll have to check again. Do you have a link or some pictures with the oil trap between the PCV valve and the manifold?
 
acontour said:
I thought the valve cover on the Zetec pushed air out instead of sucking it.
Click to expand...
nope


I'll have to check again. Do you have a link or some pictures with the oil trap between the PCV valve and the manifold?
Click to expand...

the oil separator is bolted to the side of the block behind the exhaust manifold. the PCV valve fits in a hole in the side of the separator and then there is the hard line that wraps around the block to the intake manifold.
 
striker2 said:
nope




the oil separator is bolted to the side of the block behind the exhaust manifold. the PCV valve fits in a hole in the side of the separator and then there is the hard line that wraps around the block to the intake manifold.
Click to expand...

OK , thanks. Yeah I know where the oil separator is..Had to change it to another block. SO then I guess if it sucks air then the air from the intake should force air throught the valve cover hose ..Especially under WOT like you said.
 
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