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#1
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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 |
#2
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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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Time for my very own long list of mods: 92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler I don't care if Subaru says it's STI...it will always be STi to me |
#3
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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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First the smiles, then the lies. Last comes gunfire. |
#4
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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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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#5
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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? |
#6
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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 |
#7
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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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Matt Locker Link 2015 BRZ Limited 6MT 92 Ebony LS-L ECUtune Stage2av1, Z32 MAF, 370cc injectors, TomsSVX intake, BontragerWorks 22mm RSB #003, HID Hi and Lo beams, OT endlink and bushing mods, PWR Aluminum radiator, Harvey's QC shift kit, 2.5" flowmaster 80 exhaust, 17" Michelin Pilot Sport A/S, Poly sway bar bushings, Slotted Bradi rotors, AFBeefcake powdercoated calipers, 97 grill, and a huge set of air horns. 300,000 miles and counting 92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles 19 Subaru Ascent Premium - -Hers !. 89 DL 4x4 little red wagon - a.k.a. The immortal suby. 275k R.I.P. |
#8
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Cam covers?
which ones are they? cheers |
#9
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Re: PCV valve? how does it work? etc
Quote:
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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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#10
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got it :)
Thx Trevor
actually ill go check if i got proper hose to replace that one... i ve got an oil capable hose which can have pressure up to few atmospheres...which is more then enough i think well i guess i should start eliminating possible source of problems 1 by 1 and get to the actual source eventually lols (mite renew my engine doing that lols) |
#11
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Re: got it :)
Quote:
The hose is under only a small level of vacuum rather than pressure. Anything oil resistant and resonably substantial should suffice. N. B. I am not simplifying my words in posts to you as I know you are keen to improve your English this being your second language, something others here may not appreciate. It is good to see that you can lol in spite of you problems. P.S. Thanks for the Thx. I must get myself in tune with this mod stuff !
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! Last edited by Trevor; 09-04-2003 at 12:05 AM. |
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