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10-04-2003, 09:37 PM
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#1 |
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Registered User
Join Date: Jan 2003
Location: Cold, Snowy High Level, Alberta Canada Eh
Posts: 394
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pcv valve?
Trying to simply figure out what a pvc valve is , where it is and what it does. thanx guys
dale
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2003 yamaha raptor. Stock, but it still hauls!!!! 2000 skiddo mxz 700. Camoplast 1.5 inch track, jaws twin pipes, b+b can, custom built and weighted clutch, wiseco piston, high comp heads. its very fast. wow. 72 c-10 longbox. Bright Orange. Brand new 350, rv cam, performer intake, qjet, headers, 2 1/2 inch exhaust into hooker areo chamber mufflers. Body work coming soon. "dont let yer mind wander, its to little to go places by itself." "Forget the herse, cause i'll never die"-ACDC Back In Black "If It's To Loud, Yer Just Too Old" "I Love Anything Fast Enough To Do Something Stupid In" "Instant idiot, just add beer!!"" |
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10-04-2003, 09:41 PM
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#2 |
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Registered User
Join Date: Nov 2002
Location: Florida
Posts: 42
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It's the valve on the valve cover.
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1968 SWB CST |
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10-04-2003, 09:41 PM
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#3 |
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Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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It's located on the valve cover and isconnected to the carb via a hose. I think it has something to do with vapors... If you take it off and shake it it should rattle. If it doesn't it can be cleaned with carb cleaner, or you can buy a new one for a few bucks. Hope this helps some.
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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10-04-2003, 11:26 PM
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#4 |
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Listening since '86
Join Date: Sep 2001
Location: Canada
Posts: 1,799
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the PCV valve basically scavenges hydrocarbons that escape past the pistons when your engine is running, and recirculates them back around into the engine to be burned.
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2007 Saturn Aura - hey it WAS a GM product |
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10-04-2003, 11:38 PM
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#5 |
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Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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See, Vapors or something
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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10-04-2003, 11:43 PM
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#6 |
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Formerly yellow72custom
Join Date: May 2001
Location: Austin, TX
Posts: 7,531
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Keeps your engine running much cleaner too.....good device
 Back in the day, crankcase vapors were vented out the bottom of the motor through a road draft tube.......
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'72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg |
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10-05-2003, 12:01 AM
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#7 |
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Firefighter
Join Date: Feb 2001
Location: Yellville, Ar, USA
Posts: 1,943
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Positive Crankcase Ventalation=PCV
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'72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA  
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10-05-2003, 01:04 AM
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#8 |
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Recovering Truck Driver
Join Date: Mar 2002
Location: Orleans, NE USA
Posts: 1,883
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also keeps the crankcase from building up pressure and blowing oil out of the fill caps and the seals and wherever else it can leak from.
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67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska |
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10-05-2003, 01:14 AM
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#9 |
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Black 72 Chevy
Join Date: May 2002
Location: Los Angeles, California
Posts: 662
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10-05-2003, 02:12 AM
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#10 |
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Registered User
Join Date: Sep 2003
Location: Mississippi
Posts: 36
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The PCV valve works in conjunction with the "breather vent" usually located on the "other" valve cover. The PCV valve allows the carb. to "suck in" air from the crankcase, while the breather vent allows "fresh air" into the crankcase. This "circulation" pulls a lot of corrosive vapors out of the crankcase, AND it helps to equalize pressure. If you get both plugged-up, your engine will leak oil at "places you wouldn't believe". Good idea to keep both the PCV valve and breather in good shape.
Orion 762 Last edited by Orion 762; 10-26-2003 at 02:09 PM. |
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10-05-2003, 07:14 PM
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#11 |
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Registered User
Join Date: Jan 2001
Location: Killingworth, CT. USA
Posts: 3,378
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All of the above and most importantly, should the engine backfire, it keeps the fire from backing tracking into the crankcase and blowing your valve covers off the engine.
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1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist. |
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10-05-2003, 07:38 PM
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#12 |
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Registered User
Join Date: Jul 2000
Location: Victoria,BC, Canada
Posts: 1,300
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I'm curious, other than the polluting effects, is it a problem to have no PCV valve and just the breather. Thats all my 402 had.
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71 GMC 1500 LWB |
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10-05-2003, 10:07 PM
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#13 |
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Registered User
Join Date: Sep 2003
Location: Mississippi
Posts: 36
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Spoof . . . that's all my 350 had on it when I bought it. Two auto mechanics who saw that "insisted" that the PCV was needed. Checking the internet on this: the PCV connection to the carb. is needed to pull-in fresh air (thru the breather) and carry-away the corrosive gases (blow-by from the rings). Without PCV and typical engine-ring blow-by going on, you often get corrosive vapors staying in the crankcase. A common "symptom" of this is carbon and "crud" deposited under your valve covers and along the oil channels back to the crankcase. Worst case, if these oil flow channels are blocked, you can get various valves without enough lubrication during operation.
I suspect that if you changed oil "often enough", the breather alone might work okay. I'd rather not chance it, though. Orion 762 |
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10-05-2003, 10:55 PM
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#14 |
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Registered User
Join Date: Jan 2003
Location: Chandler, AZ
Posts: 189
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A car that only has breathers will constantly smell like fumes, especially if you are in an open roadster, or an old truck that the floorboards, firewall, tranny area are not sealed well.
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10-06-2003, 03:27 AM
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#15 |
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Registered User
Join Date: Dec 2002
Location: Tampa
Posts: 1,191
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Rumor has it that a PCV will help the rings seal to the cylinders. I personally replace them with nice, pretty breathers myself.
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'68 Short Step LS1/T56, Hydratech, Fatman Fabrications Stage III, Baer, Hot Rods to Hell, US Body, S&W, etc |
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10-26-2003, 12:11 PM
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#16 |
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Registered User
Join Date: Jul 2002
Location: Ventura, Ca.
Posts: 87
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I have been experiencing blow by, especially when I go on long trips and the oil has time to drip down onto my headers to create a plume of blue smoke as I drive down the highway. It's only doing it on the passenger side v/c breather. It's the only breather I have, along with the PCV on the front driver valve cover. Would it be possible to pull that breather and put in another PCV? Or would the blow by oil make its way up the PCV hose into the carb. I have blow by on both sides, but no problem coming through the PCV on the driver side. I'm just getting tired of oil dripping down onto my headers. I guess I could change the valve seals, but If I do that, I will want to get started on bulding my Stroker that I plan on throwing in 6 months from now. I'm just looking for something less messy to get me by until then. Any advice would be greatly appreciated.
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Aaron Ventura, Ca. 1972 GMC Super Custom SB350/TH400 |
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10-26-2003, 09:37 PM
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#17 |
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Pennyless Fool
Join Date: Oct 2003
Location: Forney,Tx
Posts: 439
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The pcv valve is supposed to cause an airflow through the block. In through the breather and out through the pcv, circulation. On my 283 the breather is at the front of the intake (supposed to be anyway, soon will be) and pcv is at the rear so I'm guessing air flows front to back. Yours is breather on one cover and pcv on the other causing airflow from side to side. If you put a second pcv in you would have no place for air intake into the block and would also disrupt flow through the block.
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10-26-2003, 10:12 PM
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#18 |
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Registered User
Join Date: Apr 2003
Location: missouri city, tx
Posts: 4,486
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not to be confused with pvc
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70 longbed 496/th400/Ford 9" |
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10-26-2003, 11:19 PM
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#19 |
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Account Suspended
Join Date: Mar 2003
Location: ** THE FALL GUY **CHICAGO IL
Posts: 5,883
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TWO PCV'S
 THEN YOU WOULD HAVE A DOUBLE SUCKER U GOT BLOW BY U NEED RINGS |
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10-27-2003, 10:37 AM
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#20 |
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Registered User
Join Date: Jul 2002
Location: Ventura, Ca.
Posts: 87
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Could I just plug the hole that the breather is in to stop oil from dripping out of the breather and onto my headers? I know this motor needs a rebuild, but If I tear into it I might as well go all the way. I know my truck needs a ring job, etc., but unfortunately, I'm not financially prepared to throw the stroker in just yet.
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Aaron Ventura, Ca. 1972 GMC Super Custom SB350/TH400 |
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