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#1 |
New Member
![]() Join Date: Jul 2023
Location: Los Angeles, CA
Posts: 6
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Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
I recently inherited my Dads 69 GMC Stepside, motor runs great! I’m a newbie at this so I apologize in advance for my inexperience. At the rear of the valve cover there is a hose and coming from the top, leaks oil. What’s does this do? Is this an EGR valve? Appreciate your input and advice. Where do I find replacement parts?
Thanks! |
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#2 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
That's your PCV valve.
Positive Crankcase Ventilation. The other end should go into your carburetor somewhere. It's a one-way valve. If vaporized oil is bypassing it, the valve is stuck. Replace the PCV valve and maybe the grommet, and you should notice an improvement. Unlike prior model years, when vaporized oil was let out from a vent on top of the engine, in 1967 GM was nudged by the Federal Gov't to make those vapors get recycled into the carburretor to get burned with fuel/air during ignition. On my '68 292 L6 -- which is much like yours -- fresh air is sucked into the crankcase thru the Air Cleaner and oil vapors are sucked out thru the PCV Valve at the rear, and funneled into the carbureter to be burned. I no longer run a Monojet, but the principle remains the same. The fatter hose forward goes into the side of the valve cover. A filter in the air cleaner screens the air to the snorkel under it. The rear hose comes out of the PCV valve at the back of the valve cover and into the Carb. I usually replace the PCV once a year, just before Emissions testing. They are easily available at any auto parts store.
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Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 06-25-2024 at 01:38 AM. |
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#3 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,444
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
Yup, PCV valve. The hose on the valve cover where the oil fill cap is goes to the bottom of the air cleaner housing for filtered air. It probably has a spark arrestor screen on it, inside the perimeter of the air filter. The valve could be clogged, or the engine could have a lot of blow-by, which is combusted fuel and air leaking past the rings. That's easy to check. Just remove the oil fill cap and see if smoke comes out. You can verify if the PCV valve is clogged by pulling it from the valve cover and putting thumb on it. If engine speed doesn't change it's clogged, or potentially the hose is collapsed.
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~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#4 |
New Member
![]() Join Date: Jul 2023
Location: Los Angeles, CA
Posts: 6
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
Thank you @steeveedee and @68OrangeSunshine for your prompt response and I appreciate your help! 🍻.
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#5 |
Registered User
Join Date: May 2011
Location: Northern Calif.
Posts: 3,699
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
More pics of your rig are a necessity!
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#6 |
Who Changed This?
![]() Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,444
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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#7 |
Senior Member
![]() Join Date: Jan 2012
Location: Texan, back in TX
Posts: 2,160
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
Dang! In AZ they do emissions testing on 1968 vehicles?
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#8 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
Uh-huh. Any vehicle 1967 model year or later.
The L6 292 in my '68 C/10 Stepside usually passes, but I have a set of leaner Edelbrock metering rods and jets to put in the 1404 carb and try for a second pass if it doesn't. The 350 V8 in my '71 GMC Jimmy was even worse, being looked at as a Hotrod Badboy. I got around that by getting it registered as a vintage vehicle with a Yellow [69/72] Year-Of-Manufacture 1971 AZ plate and collector car insurance.. Now it's emissions-exempt and I can register it for 2 or 5 years at a time. I went with 2 years... My '67 K/10 Suburban with a 454 BBC was a beast to get thru emissions. Now I have a White [66/68] AZ plate for it standing by, if I can ever ressurrect it. ![]() ![]()
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Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 06-25-2024 at 01:41 AM. |
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#9 |
New Member
![]() Join Date: Jul 2023
Location: Los Angeles, CA
Posts: 6
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
Here you go. Exterior Photos
Last edited by LockDoc; 06-25-2024 at 02:54 PM. |
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#10 |
New Member
![]() Join Date: Jul 2023
Location: Los Angeles, CA
Posts: 6
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
More motor pics
Last edited by LockDoc; 06-25-2024 at 02:57 PM. |
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#11 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
Long bed Stepside. Way cool. Those are rare. Keep that rear step bumper. It's a good anvil.
What's the Odometer reading, Bee?
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Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 06-25-2024 at 01:42 AM. |
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#12 |
Registered User
Join Date: May 2011
Location: Northern Calif.
Posts: 3,699
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
That's a good old truck! I agree, keep that back bumper.
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#13 |
New Member
![]() Join Date: Jul 2023
Location: Los Angeles, CA
Posts: 6
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
It’s actually a short bed and needs some good ol TLC on the body and bed. I’m thinking of just buying the steel panels from LMC Truck online to save on labor work just to make repairs on rusted panels. Cheaper to buy the panels then have the truck painted.
As far as the bed is concerned I’m leaning towards replacing the wood slats with a synthetic lumber like Trex. Last edited by LockDoc; 06-25-2024 at 02:58 PM. |
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#14 |
Senior Member
![]() Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,286
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Re: Help! 1969 GMC 250 CID, what’s leaking on my valve cover.
The Wide Angle lens shots threw me off.
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Every 25 years I like to rebuild that 292, whether it needs it or not. |
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