PCV valve
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FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
PCV valve
I have a queston. Relax.. it's not a hard one.. I hope. 
My question is about the PCV valve and how they commonly operate on these trucks. I gather from a brief search online that it should restrict airflow at high vacuum(idle) and let more air pass when the engine is under load and vacuum drops. Is this right and is it how it should operate on these trucks? The one on my 5.0 right now passes a lot of air at idle.. I actually though I had a vacuum leak at first it makes so much noise, but that noise stops when I pinch the hose between the valve and intake. I should state that I have re-routed the hose to the central vacuum tree on the top of the intake instead of the short connection to the back. Anyway.. do I have a bad PCV valve?
My question is about the PCV valve and how they commonly operate on these trucks. I gather from a brief search online that it should restrict airflow at high vacuum(idle) and let more air pass when the engine is under load and vacuum drops. Is this right and is it how it should operate on these trucks? The one on my 5.0 right now passes a lot of air at idle.. I actually though I had a vacuum leak at first it makes so much noise, but that noise stops when I pinch the hose between the valve and intake. I should state that I have re-routed the hose to the central vacuum tree on the top of the intake instead of the short connection to the back. Anyway.. do I have a bad PCV valve?
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FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
Yes... I plan to pick up another asap. I'm still curious to know if anybody else has noticed anything peculiar about the Ford spec valves though, every one I have seen recently seems to be nothing more than a capsule with a ball in it, I thought there was supposed to be a spring in there too?
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FTE Legend
Joined: Jun 2006
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Likes: 1,499
From: Ottawa, Ontario
Yep.. I just found a nice cross section view of what the valve should look like, and it would certainly seem mine isn't right.. it's passing a ton of air at idle which is the complete opposite of how it should work.
Senior User
Joined: Sep 2007
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From: Iowa
Not completely certain, but as far as I know they are just a check ball, no spring. Have always just used the 'rattle' test to check them. No rattle or dull, sticky rattle, replace (or clean with carb cleaner if you are super cheap.) Free and easy rattle, good part.. Never have had one apart to say with certainty and not sure all applications are of the same type, so?????
Senior User
Joined: Nov 2008
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From: okc,oklahoma
carb cleaner if your cheap? where i live carb cleaner actually cost $2 more than the valve itself
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Posting Guru
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I like the "carb cleaner if you are super cheap" one. I never even thought of doing that. I have a friend who would love that one, he's the cheapest SOB in the world, so he's probably already doing it.
The valves are so cheap that I just replace them in both of my vehicles every two years along with ignition tune-ups. I buy them when I go to get my parts and don't even inspect the old ones, I take them out and throw them away.
The valves are so cheap that I just replace them in both of my vehicles every two years along with ignition tune-ups. I buy them when I go to get my parts and don't even inspect the old ones, I take them out and throw them away.
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Joined: Nov 2006
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Paul, It's funny that I should find this thread after yesterday. My high idle problem turned out to be a bad PCV valve. I guess over time spring gets weak & causes it to collapse too easily & like you I rerouted the hose to the vacuum tree.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
The main job of the one way check valve PCV valve is to prevent crankcase explosion.
If the engine back fires into the intake the PCV Valve will not let the fire go passed it to the crankcase..
When the engine is running the valve should be open and the vacuum restricted through a orifice hole in the orifice washer.
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If the engine back fires into the intake the PCV Valve will not let the fire go passed it to the crankcase..
When the engine is running the valve should be open and the vacuum restricted through a orifice hole in the orifice washer.
/
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