Extended highway speed = oil usage.

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Don't know what kind of PCV systems you guys have but mine works like this.

The PCV valve is connected to the intake. The PCV valve acts as a regulator only allowing so much flow into the intake and in case of a backfire a check valve to keep the backfire from entering the crankcase. Air is drawn in through the valve covers which is connected to the pre-TB intake and after the MAF. This way the extra air is measured by the MAF and does not act like a vacuum leak. The PCV valve is open and regulating anytime there is intake vacuum. At WOT when there is no vacuum the valve closes due to gravity but does not completely seal shut. If there is crankcase pressure due to blow-by it will be pushed past the partially closed PCV valve and into the intake or will also be drawn in to the TB due to the pressure difference between the pre-TB intake track and the crankcase.

In my experiments the filter will not stop anything due to the fact you are filtering a gas. Any liquid being sucked up will be stopped but this is a failure of the oil separator or it is overcome due to too much flow or too much blow-by.

I use a flow through can which condenses the gas and then drains after the car is shut off. This is a 3" x 9" aluminum tube. The small fuel filters get hot and don't condense anything. You will of course find something in them but not near what is really flowing through them. My condensation can will collect 100 ml in 200 miles. BUT this is with the PCV intake at the valve covers plugged. With the PCV intake connected normally the amount condensed is double that.

[ December 25, 2003, 05:33 PM: Message edited by: SHOZ ]
 
If you read that link posted above and look in any repair manual that expalins PCV, it states that when under vacuum, the plunger is pulled almost completely shut. Which makes perfect sense. When idling, or not under load, crankcase pressure is minimal, and there does not need to be that much flow through the system. When you mash the gas, vacuum goes to 0, and the plunger in the valve is not pulled foward, so it increases the amount of flow possible through the valve, which also makes sense, as that is when the most blow-by and need for crankase evacuation occurs. Just because there is no vacuum when under heavy load does not mean there is no airflow; on the contrary, there will be more airflow but less restricion through the valve and the intake manifold, which allows the plunger to stay open more.
 
Taken directly from that link above:


The PCV Valve
The most critical part in the PCV system is the flow control valve, commonly referred to as the PCV valve. The purpose of the PCV valve is to meter the flow of the vapor from the crankcase to the intake manifold. This is necessary in order to provide proper ventilation for the crankcase, while not upsetting the fuel/air mixture for combustion.

Blow-by gases and vapor should be removed at about the same rate they enter the crankcase. Since blow-by is minimal at idle and increases during high speed operation, the PCV valve must control the flow of vapor accordingly. The PCV valve is designed to compensate for the engine ventilation needs at varying engine speeds. It is operated by manifold vacuum which increases or decreases as engine speeds change.

For example, at low or idle engine speeds manifold vacuum is high. This pulls the plunger to the extreme forward position, or manifold end of the valve. Due to the shape of the plunger, vapor flow is reduced to a minimum. The low rate of the flow is adequate for ventilation purposes and will not upset the fuel/air mixture ratio.


At high speeds manifold vacuum is decreased. The plunger is only drawn to a point about midway in the housing. This allows a maximum flow of vapor. Since the engine needs more fuel/air mixture at high speeds, the introduction of more vapor does not affect performance. In the event of a backfire, pressure from the intake manifold forces the plunger to the closed or engine-off position. This prevents the backfire flame from reaching the crankcase and exploding the combustible vapor.
 
it isnt "bullocks" as someone said.
if you think about it logically, an air compressors oil trap has a drain valve on the bottom, so that you are suppose to drain its container ever so often, or it may have an automatic valve, like mine.

using a fuel filter which has no provision to drain its self, just leads to filling it up to the point where the oil is forced through. besides that, a fuel filter is NOTHING like an oil trap installed on an air compressor. using a fuel filter on your pcv line is foolish at best, dangerous at worst. as when the filter is full of oil and ends up going through the media anyways, this presents a decent restriction, as a fuel filter isnt designed to deal with the thickness of an oil. last i checked, gasiline was pretty thin....
 
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