breather filters effect on pcv system (info)
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From: W.A
breather filters effect on pcv system (info)
I know there has always been a debate if breather filters are good or bad i'm not here to dabate that or try to start one, just shairing something i read in my chilton's manual.
Some may already know this and some may have understood it wrong (or got only 1/2 the story) like me.
As it has been exlpained to me the pcv system draws fresh air from the intake through the hose leading to the vlave cover. Well thats only half the story.
Here's what i read....
The pcv system is designed to prevent blow-by gas from escaping to the atmosphere by drawing it directly into the intake manifold. The pcv valve containes a spring loaded plunger which is lifted in proportion to intake manifold vacuum. Under high vacuum, blow-by is returned directly to the manifold through the breather chamber and pcv valve with fresh air. When the intake manifold vacuum decreases (wide open throttle) and vacuum in the air cleaner increases, the pcv valve closes and the blow-by is returned through the cylinder head cover breather hose and into the air cleaner. The pcv valve also acts as a check valve when the engine backfires to prevent crankcase explosion...
So when at idle the blow-by exits through the crankcase into the breather chamber, through the pcv hose and through the pcv valve into the manifold, at that time fresh air is being drawn into the valve cover through the breather hose (usually connected to the intake pipe) to complete the cycle.
When under load (acceleration, with less or no vacuum or boost) the pcv valve closes (blocks that route) so the pcv hose and valve are inactive, and blow-by is "sucked" out of the valve cover by the breather hose and into the intake manifold. So air flows into the valve cover and blow-by exits through the breather hose (dual purpose).
Like I stated before it was always explained to me that ONLY fresh air was drawn into the valve cover through the breather hose thus the Possitive Crankcase Ventilation (PCV).
This also explains why my car would smoke when i had the breather filter or (for a short period) when i had my breather hose unhooked (not hooked to the intake before the turbo).....
I now have my breather hose hooked into my "intake" between the turbo and filter, and have no smoke....
Just a FYI any and all comments are welcome
Some may already know this and some may have understood it wrong (or got only 1/2 the story) like me.
As it has been exlpained to me the pcv system draws fresh air from the intake through the hose leading to the vlave cover. Well thats only half the story.
Here's what i read....
The pcv system is designed to prevent blow-by gas from escaping to the atmosphere by drawing it directly into the intake manifold. The pcv valve containes a spring loaded plunger which is lifted in proportion to intake manifold vacuum. Under high vacuum, blow-by is returned directly to the manifold through the breather chamber and pcv valve with fresh air. When the intake manifold vacuum decreases (wide open throttle) and vacuum in the air cleaner increases, the pcv valve closes and the blow-by is returned through the cylinder head cover breather hose and into the air cleaner. The pcv valve also acts as a check valve when the engine backfires to prevent crankcase explosion...
So when at idle the blow-by exits through the crankcase into the breather chamber, through the pcv hose and through the pcv valve into the manifold, at that time fresh air is being drawn into the valve cover through the breather hose (usually connected to the intake pipe) to complete the cycle.
When under load (acceleration, with less or no vacuum or boost) the pcv valve closes (blocks that route) so the pcv hose and valve are inactive, and blow-by is "sucked" out of the valve cover by the breather hose and into the intake manifold. So air flows into the valve cover and blow-by exits through the breather hose (dual purpose).
Like I stated before it was always explained to me that ONLY fresh air was drawn into the valve cover through the breather hose thus the Possitive Crankcase Ventilation (PCV).
This also explains why my car would smoke when i had the breather filter or (for a short period) when i had my breather hose unhooked (not hooked to the intake before the turbo).....
I now have my breather hose hooked into my "intake" between the turbo and filter, and have no smoke....
Just a FYI any and all comments are welcome
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