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I just noticed today that the hose coming from the PCV valve looks like it's pinched. The PCV valve was replaced 2 weeks ago and everything seems to be fine. Is this normal? I noticed that my friends's 97 accord does the same thing.
 

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can u take a pic? i dont no what u mean by pinched...it recirculates the oil from the engine...u can just put a breather filter on there but they get dirty rather quickly...
 

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Pinched as in the hose collapsing? I had this with the hose that came with my oil catch can (hooks into the PCV system) the hose wasnt up to scratch so I got some strong fuel line hose and that fixed it =)

Your car will run like ass if the pcv system isnt working and the hose "pinched" like that is not good for it!
 

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Discussion Starter #4
The car runs perfect, but it looks collapsed (pinched, whatever). So the fuel line fixed the problem? I have some extra fuel lines somewhere. I might just give it a try. Thanks very much!
 

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deiz, you mean it recirculates the air from the motor lol, not the oil.

well, sometimes it does recirculate oil hahahaha but thats obviously not what its meant for lol
 

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motoxxxman said:
deiz, you mean it recirculates the air from the motor lol, not the oil.

well, sometimes it does recirculate oil hahahaha but thats obviously not what its meant for lol
The PCV valve is for Positive Crankcase Ventalation, its used to suck gasses from the valve cover back into the intake to be re-burnt. It is an emissions system.
Of course because the valve cover has oil and stuff in it, oil vapours also get sucked up with these gasses and go into your intake system and leave a black oil sludge over everything over time.
Oil catch cans, catch this oil vapours so you dont have it going through your intake system but still get the unburnt gases through the system like its meant to =)
 

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Yup, it's the one (1) emissions control bit that actually helps the engine!

Those oil vapors condense into that same sludge in the engine, which is where the grime and gunk that builds up over time comes from.

Also, the lower the pressure inside the block the more power it'll put out.
Untill it was made illegal, the NHRA guys had big vacuum pumps hooked up to the engine, keeping the crankcase at a very solid level of vacuum.

Our PCV system, obviously, don't create a vacuum in there, but with the flow-through design it still keeps the sludge from forming nearly as fast.
 

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hmm, so what would happen if we plug the line going from the valve cover to the intake tube? i know it would cause some idle issues, but it would create vacuum in the crankcase wouldnt it? would that do anything as far as performance for us?
 

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The crankcase IS kept at a slight vacume I believe, the pcv valve opens at a certain point to let the gasses through, when it collapses its completley open and your engine will run like uber shit. (see my pcv valve thread) :]
 

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ok, so heres an idea. put a pump on the valve cover where the pcv valve normally would be, plug the hose from the valve cover to the intake tube, and have that pump suck the air out of the crankcase creating a vacuum in the crankcase, and have it blow the air into a seperate canister outside the motor. then run the pcv system to this canister, with a filtered vent so it doesnt pressurize the pcv system. that wouldnt affect the operation of the pcv system, but it would create a major vacuum in the crankcase.

think that would do anything for performance?
 

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It ought to help it, really.
I can't say how much, or even exactly why, but it would deffinitely help.

The trick of course is to make more extra hp then the pump consumes itself.

The stock pcv system doesn't keep the crankcase under any vacuum at all.
The air removed from the crankcase by the pcv-intake manifold hole is imediatly replaced by air coming through the intake hose-valve cover pipe.
 

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Bobnova said:
The stock pcv system doesn't keep the crankcase under any vacuum at all.
The air removed from the crankcase by the pcv-intake manifold hole is imediatly replaced by air coming through the intake hose-valve cover pipe.
Hmm that is what I always thought but how come when the PCV valve fails it gets stuck open and the car runs like crappp?
Hmm wait... Ahhh... maybe because with it stuck open ALOT of oil vapours etc get into the intake and screw up the fuel mixture!!
That would make sence, because on my prelude I had a PCV valve die but it didnt make much of a difference except the oil catch got a bit more stuff in it, whereas on my project lude with stock PCV system it ran like a doggg and was bogging down heaps and all sorts of things were going wrong!
 

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The PCV valve exists for two reasons.
1: if you get backfire up the intake manifold, the PCV valve closes (airflow going the wrong way through the valve) to prevent the flame front from getting into the crankcase, and causing an explosion.

2: It acts as a restrictor, to prevent the engine from sucking in too much air through the system, and having the idle raise.
 
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