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1979 Chevy Truck PCV Valve

Tiny
ASRNLLPS
  • MEMBER
  • 1979 CHEVROLET TRUCK
  • V8
  • 4WD
  • MANUAL
  • 121,000 MILES
How can I tell if my PCV valve is working? My truck ran good and then it seemed like it had all of a sudden lost power. It didn't want to get up to speed like normal. If I ease off the gas a little it runs a little better, but you can tell when you shift that something is not right either not enough power, too much fuel, I'm not sure. I just tuned it up but without help-plugs, wires, cap and rotor. I noticed 2 plugs that looked not right and I have to put a quart of oil in every week but I have a very, very small oil leak.
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Wednesday, June 30th, 2010 AT 6:16 PM

8 Replies

Tiny
BLUELIGHTNIN6
  • MECHANIC
  • 16,542 POSTS
Hello and thanks for donating

The PCV valve should be replaced every 50k miles or so, since this is such an old truck you may want to just replace the PCV valve instead of testing it. At the very least, just clean the PCV valve. When you said that 2 plugs didn't look right, what exactly did they look like? Black, lot of carbon build up?
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Wednesday, June 30th, 2010 AT 8:58 PM
Tiny
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The plugs were black like used oil with an oily residue. I just tuned it up a month ago. I pulled all the plugs today and changed one. The one I changed looked like the others I had pulled before but this one had some kind of chunk on it. My engine was getting warmer than normal and I changed the thermostat and it seems fine now and running better. I saw pictures of spark plugs and that's why I think I need a new PCV valve and my truck is using oil but not leaking it out. But I've never changed one or even looked in the valves. My husband says its where the hose connects to the carb. What am I getting into? Will I need to get valve gaskets when I take the valve cover off? I don't even know what the PCV valve looks like. My husband has become a truck driver so repairs have been left to me, I don't mind. Thank you for helping me.
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Wednesday, June 30th, 2010 AT 11:32 PM
Tiny
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  • MECHANIC
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It's not that bad of a job. you could just remove the valve and shake it. if you hear the valve rattling then it's still good. follow the steps below to help with removing it..the valve will look similar to the pic below..

Locate the valve cover (most often where the oil filler cap is located) and look for a plastic tube that runs from the valve cover to the intake manifold. Some vehicles may have the PCV valve located closer to the intake manifold side, but most are on the valve cover side of the tube.

Disconnect the tube from the PCV valve. The outlet connection of the valve is tapered and simply unplugs from the hose with some wiggling. Use the needle-nose pliers (gently) to assist in the wiggling motion to remove the hose from the PCV valve outlet.

Remove the PCV valve from the valve cover. The PCV valve sits into a rubber seat and can be pried out of position in the valve cover with some convincing. Often times, this can be done by hand, but use the needle-nose pliers (angled needle-nose pliers can be useful in hard-to-reach PCV valves) to wiggle it out of the rubber seat.

Clean the valve with carburetor cleaner or replace with a new one and reconnect by plugging it into the rubber seat, aligning the outlet connection, and reconnecting the rubber hose from the intake manifold.


https://www.2carpros.com/forum/automotive_pictures/261618_Noname_2413.jpg

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Wednesday, June 30th, 2010 AT 11:40 PM
Tiny
ASRNLLPS
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Sounds easy enough and I have all the tools I need. Would this cause my truck to use a quart of oil a week? That seems like a lot to me and I don't think it's because its old but it might be. What's your opinion? Thank you so much for helping me, I really appreciate it.
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Thursday, July 1st, 2010 AT 12:53 AM
Tiny
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A quart a week is a lot, is there no visible leaks of oil? A restricted PCV valve can cause excess pressure to find new avenues to vent, and an oil gasket or seal is usually "blown out" to let this pressure escape which would cause a visible oil leak.
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Thursday, July 1st, 2010 AT 1:01 PM
Tiny
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No. No oil leaks where it would be a puddle. There is a leak to the front of the motor but I can't locate it. It's very small. I'm going to clean my engine and try to find it. I can see oil dripping slowly down the water hoses in the front down onto the crossbar there and onto the ground. Its on the front passenger side, same side with the fouled plugs. No oil leaks from the oil pan or plug and the oil filter looks good too. Any ideas?
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Thursday, July 1st, 2010 AT 1:20 PM
Tiny
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Best thing to do would be what you said, clean the engine very good then inspect it closely to see exactly where the oil is coming from. There are many gaskets, seals etc. That it could be so I wouldn't want to just throw guesses at you.
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Thursday, July 1st, 2010 AT 1:31 PM
Tiny
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No problem I understand. Thank you very much for all your help and time. I appreciate it and God Bless.
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Thursday, July 1st, 2010 AT 1:34 PM

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