Catch Can
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Not needed. The filter to oil fill neck is the fresh air INLET to the engine. It is there to let air IN to replace what the pcv is pulling OUT. If you have oil filling that tube and the air inlet tube to the throttle body, you have a problem. The pcv may be bad or there is too much blowby for the pcv to handle. Either way, that line should be clear.
Fleet Mechanic
Joined: Aug 2015
Posts: 1,838
Likes: 364
From: Candy Mountain
It will function the same either way. Air should only move into the crankcase when the PCV valve is open, with the evacuated air being drawn into the manifold which is accounted for in the computers calibration.
In theory it is a can with two ports, the PCV valve and the breather. Vacuum on either end without a vent on the other end won't move much if any air. The air, fumes, and oil in the crankcase are irrelevant to the fuel air ratio until they are drawn into the combustion chamber via the intake manifold.
The vacuum that exists in the air inlet tubes is pulling against a brick wall unless there is a leak in the crankcase. When the PCV valve opens it will have a stronger vacuum signal than that in the tube and the air would be drawn into the intake.
Reality is that most of these engines probably have some crankcase leakage, so sure you may see some air, fumes, and oil being drawn into the air filter box or air inlet tubes.
In theory it is a can with two ports, the PCV valve and the breather. Vacuum on either end without a vent on the other end won't move much if any air. The air, fumes, and oil in the crankcase are irrelevant to the fuel air ratio until they are drawn into the combustion chamber via the intake manifold.
The vacuum that exists in the air inlet tubes is pulling against a brick wall unless there is a leak in the crankcase. When the PCV valve opens it will have a stronger vacuum signal than that in the tube and the air would be drawn into the intake.
Reality is that most of these engines probably have some crankcase leakage, so sure you may see some air, fumes, and oil being drawn into the air filter box or air inlet tubes.
Thread Starter
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
It will function the same either way. Air should only move into the crankcase when the PCV valve is open, with the evacuated air being drawn into the manifold which is accounted for in the computers calibration.
In theory it is a can with two ports, the PCV valve and the breather. Vacuum on either end without a vent on the other end won't move much if any air. The air, fumes, and oil in the crankcase are irrelevant to the fuel air ratio until they are drawn into the combustion chamber via the intake manifold.
The vacuum that exists in the air inlet tubes is pulling against a brick wall unless there is a leak in the crankcase. When the PCV valve opens it will have a stronger vacuum signal than that in the tube and the air would be drawn into the intake.
Reality is that most of these engines probably have some crankcase leakage, so sure you may see some air, fumes, and oil being drawn into the air filter box or air inlet tubes.
In theory it is a can with two ports, the PCV valve and the breather. Vacuum on either end without a vent on the other end won't move much if any air. The air, fumes, and oil in the crankcase are irrelevant to the fuel air ratio until they are drawn into the combustion chamber via the intake manifold.
The vacuum that exists in the air inlet tubes is pulling against a brick wall unless there is a leak in the crankcase. When the PCV valve opens it will have a stronger vacuum signal than that in the tube and the air would be drawn into the intake.
Reality is that most of these engines probably have some crankcase leakage, so sure you may see some air, fumes, and oil being drawn into the air filter box or air inlet tubes.
Fleet Mechanic
Joined: Aug 2015
Posts: 1,838
Likes: 364
From: Candy Mountain
It is benefit in catching oil. It is a detriment in that it is a further use of and potential leak for manifold vacuum.
The ideal would be a screen that keeps oil out of the PCV valve in the first place.
But, until someone brings that to market we will make do with what we have.
The ideal would be a screen that keeps oil out of the PCV valve in the first place.
But, until someone brings that to market we will make do with what we have.
Hotshot
Joined: Sep 2001
Posts: 11,958
Likes: 228
Some carbed vehicles did have the breather tube connected to the air cleaner.
I have seen countless trucks like ours suck oil up through that into the intake or air tube, even back when they were only a few years old with under 100k on them.
I'm not saying that the old previous way of venting to the atmosphere is the best way, I am just questioning how is it that design is not going to act like a second non valved PCV connection? It seems that the breather being open to outside air would allow the PCV to actually evacuate crank case fumes more efficiently since fresh air could be drawn in without fighting the air intake suction.
Hotshot
Joined: Sep 2001
Posts: 11,958
Likes: 228
Some vintage car friends of mine like this ME Wagner PCV valve and say it works quite well for oil being sucked up the PCV hose.This is usually on non stock mildly built hot rodded engine setups.
Dual Flow Adjustable PCV Valve ? M/E Wagner Performance Products
Dual Flow Adjustable PCV Valve ? M/E Wagner Performance Products
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