PCV problems
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Freshman User
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PCV problems
Hello,
I have a new PCV installed on my truck 1990 460 with 5 speed. My idle is 900 to 1100 rpms and when I put a finger over the pcv my rpms drop down to normal levels. It did the same with the old one too. I got the pcv from Napa.
My pcv has won serious sucking power going through it. I use a lot of oil as well.
Any ideas what or if anything I can do.
I have a new PCV installed on my truck 1990 460 with 5 speed. My idle is 900 to 1100 rpms and when I put a finger over the pcv my rpms drop down to normal levels. It did the same with the old one too. I got the pcv from Napa.
My pcv has won serious sucking power going through it. I use a lot of oil as well.
Any ideas what or if anything I can do.
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Freshman User
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My crankcase is connected to the air box. There is no oil in air cleaner. I can take the pvc out of the valve cover and put my finger on the pcv intake and the rpms will drop to normal level.
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I had my cat removed when I got a new muffler.
I don't have any scored bores or lips on the cylinders when I changed the heads. It runs well and has decent power. I get 12 to 13 mpg. But just trying to figure out things to improve my old truck. I do this because I really like my truck and my wife utterly hates it. Lol.
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The valve rattle sound does not happen all the time. Sometimes it happens when I hammer it or have a heavy load on it. But it does not happen all the time either.
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Cargo Master
Joined: Mar 2002
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From: W (BY GOD) V
I have a new PCV installed on my truck 1990 460 with 5 speed.
My idle is 900 to 1100 rpms and when I put a finger over the pcv my rpms drop down to normal levels. It did the same with the old one too. I got the pcv from Napa.
My pcv has won serious sucking power going through it. I use a lot of oil as well.
Any ideas what or if anything I can do.
If the idle drops when you block-off the valve it is indicating either the actual valve is bad/bad design/not calibrated properly for the application or is drawing outside air somewhere before the valve (bad valve grommet/major gasket and/or seal leak in the engine).
The increased RPM is as a result of a vacuum leak, leaning out mixture/fuel curve.
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Cargo Master
Joined: Mar 2002
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From: W (BY GOD) V
If the idle drops when you block-off the valve it is indicating either the actual valve is bad/bad design/not calibrated properly for the application or is drawing outside air somewhere before the valve (bad valve grommet/major gasket and/or seal leak in the engine).
That valve is a controlled orifice and the spring calibrated to the exact application. Does the valve fit tightly in the grommet?
MOTORCRAFT parts are available on the net cheap. I don't understand going to these auto stores. NAPA used to be quality. It no longer is. It's a crap shoot when you open the box.
Simply put, you have a lean fuel mixture. This will also cause the valve rattling @ load. If the valve is sucking excess fumes/oil from the crankcase, the fuel mixture will also become leaned out.
Lead Driver
Joined: May 2011
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The "valve rattle" is ping, and you don't want to allow it to occur.
The pcv system is a vacuum leak, no way around it, although the computer is designed to at the very least be aware of the metered (at least "supposed" metered) air coming through the pcv.
If you're using that much oil, you likely have bad rings, and should start with a compression test before replacing anything else. That much oil getting burned could also explain your ping, but testing for vac leaks is first and foremost.
Compression test, check for vac leaks.
The pcv system is a vacuum leak, no way around it, although the computer is designed to at the very least be aware of the metered (at least "supposed" metered) air coming through the pcv.
If you're using that much oil, you likely have bad rings, and should start with a compression test before replacing anything else. That much oil getting burned could also explain your ping, but testing for vac leaks is first and foremost.
Compression test, check for vac leaks.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
As the others have stated the PCV is a controlled vacuum leak or sorts. I believe your test is masking the real root cause.
Based on your symptoms (high idle RPM & oil consumption and pinging) I would suspect an intake manifold leak from the under side. Oil in the air/fuel mixture will cause pinging. Second on my list is leaking rings. A compression test is definitely in order and a lot easier than replacing intake manifold gaskets.
Based on your symptoms (high idle RPM & oil consumption and pinging) I would suspect an intake manifold leak from the under side. Oil in the air/fuel mixture will cause pinging. Second on my list is leaking rings. A compression test is definitely in order and a lot easier than replacing intake manifold gaskets.
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