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  #1  
Old 08-30-2003, 07:16 AM
6evil9
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PCV valve? how does it work? etc

Hi i got my oil dipstic popping up, which tells me my PCV valve is broken

ok i ve read bout replacing it..which ofcourse sounds bad for me

but what broken PCV valve can lead to and what does it actually do and how it works?
also the rubber tube going to it cracked terribly...can this one cause oil dipstic popping up? or i would have oil all around the crack? (which i dont have)

any links? or maybe someone can be kind enough to tell me bout it?

cheeeeers
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  #2  
Old 08-30-2003, 07:35 AM
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You might just have a worn o-ring on your dip-stick. Either way it's a cheap and fairly easy fix. Theres a how-to on the PCV, and the o-ring is self expanitory (get one of the same size and replace it). I'm not sure how the PCV works, though. Sorry.

edit: I read my post and realized that even though it's self explanitory, I went ahead and explained it .
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  #3  
Old 08-30-2003, 09:39 AM
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The PCV valve (positive crankcase ventilation I think) is jut a one-way check valve that lets unburned gasses out of the engine to recirculate back in with the incoming air. The hose is "outside" of the valve, so I would speculate that you are just releasing the unburned gases into the environment instead of recirculating and buring them. I don't think the hose would have anything to do with the dipstick popping out, but if the valve is stuck closed, it might.

You will probably want to replace the hose anyway, because I would guess that some of the air that should be feeding into your throttle bodies is leaking out through that broken hose, but you'll have to wait for a more educated answer on that one.
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  #4  
Old 08-30-2003, 07:22 PM
oab_au oab_au is offline
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Dipstictus erectus.

I think there is more to this than just the PCV valve. The valve is a multi function valve. At idle it is pulled right back to allow the manifold vacuum to pull fresh air down from the air box in front of the throttle bodies through the two breathers on top of the cam covers, through the crankcase, through the PCV to inlet tract, to be burnt.

At full throttle it is closed to the crankcase. The crankcase fumes are then vented back through the cam covers to the air box in front of the throttle bodies and into the inlet.

The way I see it if there is enough crankcase pressure to pump the dip stick out, then the cam cover breathers must be blocked. I don't know what is in the two black boxes on the cam covers, but there must be some kind of baffle or mesh to take the oil mist out of the fumes, may be this is blocked.

The excess pressure will then lead to oil leaking out every seal and joint in the engine.

Harvey.
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  #5  
Old 08-30-2003, 08:13 PM
6evil9
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can it be root of all my problems what so eva?

hey man what i have that yeah oil goes out every where but its not like huge leaking just abit from every seal lols what u say
plus i get problem of my engine "choking" if u know what i mean, i got another thread explaing it...

but thing is that most oil seals were changed and i still cant find why the hell my engine dont work properly and why its choking or misfiring or fuel system or air system is stuffed...

grrrrrrr i knew svx is tough but still....

anyways any further readings bout how pcv valve works and what it can cause when stuffed?
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  #6  
Old 08-30-2003, 08:21 PM
6evil9
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Lightbulb Dipstictus erectus, PCV valve phukeduptus

and yeah my PCv valve is blocked as there s no oil leak on cracked tube going to it...



and can the maniforld be dirty or stuffed ..i mean where the air goes into the engine?
and how to clean it?

i looked that taking manifold out will be such pain in one place....

thx for helpus
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  #7  
Old 08-31-2003, 07:57 AM
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If I remember right when I took off the cam covers and cleaned them up there was no screen or mesh in the breather boxes - just a baffle.
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  #8  
Old 09-03-2003, 02:14 AM
6evil9
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Cam covers?

which ones are they?

cheers
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  #9  
Old 09-03-2003, 06:49 AM
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Re: PCV valve? how does it work? etc

Quote:
Originally posted by 6evil9
Hi i got my oil dipstic popping up, which tells me my PCV valve is broken

ok i ve read bout replacing it..which ofcourse sounds bad for me

but what broken PCV valve can lead to and what does it actually do and how it works?
also the rubber tube going to it cracked terribly...can this one cause oil dipstic popping up? or i would have oil all around the crack? (which i dont have)

any links? or maybe someone can be kind enough to tell me bout it?

cheeeeers
If the tubing to the PCV valve is cracked air could be entering the manifold through the leaking tubing. In another thread I think I advised you to check all tubes going to the inlet maniflod in case any may be leaking. This is such a tube.

Put simply blow by gas collecting in the crankcase is drawn via the PCV valve and the attached hose into the manifold which is below atmospheric pressure. Therefore you will not have oil escaping from the cracks in the hose but you could have air getting in.

The arrangement provides positive crancase ventilation using " suction " derived from the inlet manifold at small throttle openings. This " suction " will also draw in outside air via a leaking hose and upset fuel mixture in the manifold. If the PCV is in fact blocked or stuck shut, ( it normally opens when under a small negative pressure ) this could make things worse as all pressure difference will be equalised via the leaks in the tubing.

However it would be expected that any effect would be more apparent at idle or near closed throttle rather than at open throttle when there is reduced vacuum ( "suction" ) and this is the reverse of what you have reported.

Even so you should replace this faulty tubing and eliminate this as a possible cause of your problem. It could be that the ECU is completely confused as a result of compensating for a lean mixture at idle and low speed.
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  #10  
Old 09-03-2003, 11:21 PM
6evil9
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got it :)

Thx Trevor

actually ill go check if i got proper hose to replace that one...
i ve got an oil capable hose which can have pressure up to few atmospheres...which is more then enough i think

well i guess i should start eliminating possible source of problems 1 by 1 and get to the actual source eventually
lols

(mite renew my engine doing that lols)
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  #11  
Old 09-04-2003, 12:00 AM
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Re: got it :)

Quote:
Originally posted by 6evil9
Thx Trevor

well i guess i should start eliminating possible source of problems 1 by 1 and get to the actual source eventually
lols

(mite renew my engine doing that lols)
" Now you are talking and you are on the right track. "

The hose is under only a small level of vacuum rather than pressure. Anything oil resistant and resonably substantial should suffice.

N. B. I am not simplifying my words in posts to you as I know you are keen to improve your English this being your second language, something others here may not appreciate.

It is good to see that you can lol in spite of you problems.

P.S. Thanks for the Thx. I must get myself in tune with this mod stuff !
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Last edited by Trevor; 09-04-2003 at 12:05 AM.
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