i understand that the PCV's job is to let harmful vapor circulate back to the engine for burning. it uses engine vacuum to circulate these vapors in proportion to engine load. now my questions is:

if you take the pcv and the vacuum source out, will the harmful vapor come out of the oil/vapor separator box at the back of the block by itself? i would think it will come out by itself, coz from what i understand the vacuum is just to meter the amount of vapor going inside the engine depending on the load. so will the vapor come out by itself? or does it really need vacuum to pull it out from the crankcase?

 

anyone?

 

Yes, you need the vacuum! it will not just come out by its self.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 57STS &raquo;</TD></TR><TR><TD CLASS="quote">Yes, you need the vacuum! it will not just come out by its self.</TD></TR></TABLE>

if so, then how come people have been successful with open loop during the early years and close loop was invented just for emission/environmental purpose only, at least that's what i know of.

anyone with any idea on this?

 

Without a PCV vacuum source, crankcase pressures will be higher. Consequently, more blow-by will occur, which will shorten engine life somewhat. That little black box on the back of the block is a liquid/vapor separator; it allows the liquid oil to drain back into the crankcase. Blow-by vapors are routed through the PCV valve into the intake manifold for burning.

 

sorry if i wasn't clear on my question...what i'm trying to know is, if i take off the pcv and just run a hose from that oil/vapor separator from the back of the block to a catch can or just vent it to atmosphere, will the vapor escape by itself out without any vacuum source.

i know sticking a pcv in there without a vacuum source is not a good idea since there's not enough pressure to push the pcv open. so i want is to take the pcv off and just run a hose but i don't know if the vapors will come out by themselves with a pcv and vacuum.

 

Without a vacuum source, crankcase pressures will be higher, as stated above. The vapors will escape to the atmosphere, so what you propose will work, sort of.

 

So you guys are saying if were concerned about the longevity of our engines we shouldn't run the back of the block to atmosphere, correct? I'm thinking about dumping it all to atmosphere but if my rings will suffer it doesn't sound like the best idea. Does anyone have any hard evidence of this happening?

 

How many times do you have to hear the same answer? Even if you run a catch can, you're still hooked up to manifold vacuum on the other end.

 

My question had nothing to do with a catch can. I don't understand the point your trying to make by telling me there is vaccum on the other end of a catch can. Obviously there is no vaccum aiding at all if the system is disabled running to atmosphere. This is applying to FI if it makes any difference.

 

You want vacuum sucking those fumes out of the crank case. Just venting to the atmosphere will not create vacuum and you will lose power. The benefits of more vacuum are better piston ring sealing thus giving you more air in on the intake stroke. If you wanna get rid of the fumes and oil from re-entering the intake stream you can run a catch can as stated above for the oil but the fumes will still be re-cirulated or you can run a pan evac system, something the domestic guys have been using for years with good results, which basically uses vacuum created by the exhaust stream rather than the intake stream.

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<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by highmilehatch &raquo;</TD></TR><TR><TD CLASS="quote">Obviously there is no vaccum aiding at all if the system is disabled running to atmosphere</TD></TR></TABLE>

Thats what he's trying to tell you is bad

 

Cool, thanks for clearing that up.