Pressure relief valve on door jamb - The 1947 - Present Chevrolet & GMC Truck Message Board Network

AirSpeed · 03-11-2010, 08:38 PM

I am painting my 72 GMC and when I took the relief valve off the door jamb I noticed that the steel at the bottom of the vent is slightly bent in, not flat. I dont know whether it is supposed to be that way or not, I looked at the other door as a reference and just noticed it has no relief valve on the jam. Now I have two questions, is the slight bend under the valve stock and why is there no valve on the passenger door? It seems like both should have one.
Thanks for any info! Aaron

Sammy · 03-11-2010, 08:52 PM

I never noticed mine being bent. But only 1 relief on my 71 GMC (DS) also. If I recall correctly 75 and newer had 1 per door.

71 super · 03-11-2010, 09:08 PM

71 was the first year for the valve and one of the ways to determine year of your cab, there are others as well but will not go into that. They only use the valve in the driver's side and it should be flat under the valve. The valve also gets a thin rubber oring around it as well to help seal against the "b" pillar.

GASoline71 · 03-11-2010, 09:11 PM

It's all tied in to the fuel tank vent/evap system. Nothin' to do with venting the cab.

Gary

AirSpeed · 03-11-2010, 09:17 PM

Quote:

Originally Posted by GASoline71

It's all tied in to the fuel tank vent/evap system. Nothin' to do with venting the cab.

Gary

It actually vents the pressure from the door when it closes, it makes it easier to close the door. It makes a big difference, my 69 doesnt have one ofcoarse and the door is much harder to close, specially with the windows closed.

**bignbad** · 03-11-2010, 09:18 PM

I am i missing something.I never herd of p.r. valve on the cab.what is it for?whats does it look like?Any pictures?My '72 doesn't have one.

AirSpeed · 03-11-2010, 09:19 PM

Thanks everyone! I will flatten out the area at the bottom. Aaron

AirSpeed · 03-11-2010, 09:22 PM

Quote:

Originally Posted by bignbad

I am i missing something.I never herd of p.r. valve on the cab.what is it for?whats does it look like?Any pictures?My '72 doesn't have one.

If you have a 72 it should be on the door jamb on the drivers side, it's around 6" tall, plastic and has a rubber one way flapper type valve on the inside. Its there to make the door close easier, without one it's much harder to close the door, my 69 doesnt have one and its much harder to close the door.

**leddzepp** · 03-11-2010, 11:06 PM

Quote:

Originally Posted by AirSpeed

It actually vents the pressure from the door when it closes, it makes it easier to close the door. It makes a big difference, my 69 doesnt have one ofcoarse and the door is much harder to close, specially with the windows closed.

This is correct. It is not tied into the fuel tank or EEC.

03-11-2010, 08:38 PM	#1
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Pressure relief valve on door jamb I am painting my 72 GMC and when I took the relief valve off the door jamb I noticed that the steel at the bottom of the vent is slightly bent in, not flat. I dont know whether it is supposed to be that way or not, I looked at the other door as a reference and just noticed it has no relief valve on the jam. Now I have two questions, is the slight bend under the valve stock and why is there no valve on the passenger door? It seems like both should have one. Thanks for any info! Aaron

03-11-2010, 08:52 PM	#2
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: Pressure relief valve on door jamb I never noticed mine being bent. But only 1 relief on my 71 GMC (DS) also. If I recall correctly 75 and newer had 1 per door. __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

03-11-2010, 09:08 PM	#3
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,079	Re: Pressure relief valve on door jamb 71 was the first year for the valve and one of the ways to determine year of your cab, there are others as well but will not go into that. They only use the valve in the driver's side and it should be flat under the valve. The valve also gets a thin rubber oring around it as well to help seal against the "b" pillar. __________________ 67 blue step side- bb 68 gold and white swb cst anniversary 68 custom swb hot rod Ls swap 69 swb cst 6 cylinder/ overdrive 69 black/black cst bb swb 70 orange and white cst Canada built truck swb bb 71 black and white super swb bb 71 red and white super swb 72 green and white super swb 4x4 62 nova wagon 400 series Ls swapped 68 Camaro 327/4 speed- 1 owner, original paint 66 Volkswagen bettle 69 auto stick Volkswagen Beetle

03-11-2010, 09:18 PM	#6
bignbad Registered User Join Date: Jan 2009 Location: highspire,pa Posts: 423	Re: Pressure relief valve on door jamb I am i missing something.I never herd of p.r. valve on the cab.what is it for?whats does it look like?Any pictures?My '72 doesn't have one. __________________ '72 chevy k20 '06 H-D Springer softail http://www.bluemooncruisers.com/ http://www.enginecycle.com/ ~Eric

03-11-2010, 09:19 PM	#7
AirSpeed Registered User Join Date: Jul 2007 Location: Fall River California Posts: 2,026	Re: Pressure relief valve on door jamb Thanks everyone! I will flatten out the area at the bottom. Aaron



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