Fresh air valve and vacuum diaphragm install mess!!! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crustysarge · 12-11-2004, 12:00 PM

OK, I recently discovered the fresh air plenum valve was broke and the diaphragm was ruptured. I ordered new ones and now can't get it put back in correctly. Now, the old valve was broke where it connected to the shaft so I don't know how it sit in the firewall hole.

I had to bend the crap out the bracket to get the shaft to line up, the tab that the shaft is supposed to ride on had to be bent down almost flush with the bracket. I linked a couple of pictures to see if someone can give me some advice. I left it alone before I broke it...The valve will not close all the way as it is now. I also took a shot of where the valve shaft sits when the white plastic mount is screwed on the firewall.

Think the hole is off? What about the replacement shaft hole, could it be drilled wrong?

http://img.photobucket.com/albums/v6...e/CIMG0334.jpg
http://img.photobucket.com/albums/v6...e/CIMG0335.jpg
http://img.photobucket.com/albums/v6...e/CIMG0336.jpg
http://img.photobucket.com/albums/v6...e/CIMG0337.jpg
http://img.photobucket.com/albums/v6...e/CIMG0338.jpg
http://img.photobucket.com/albums/v6...e/CIMG0339.jpg

jhow66 · 12-11-2004, 02:07 PM

See if this will help.

demi · 12-11-2004, 02:15 PM

Here are two reference pics on how mine is hooked up. Hope this helps.

demi

crustysarge · 12-12-2004, 04:29 AM

Thanks for the close up shot Demi. I wish mine looked like that! My problem is the shaft is coming out of the firewall at a downward angle, that is why I had to bend the tab down. It is now daylight here in Itlay so I am headed out to investigate.

Demi, is yours a factory air? The reason I ask is because I see the white nylon plate is appears to be perpendicular to the firewall and mine is installed at an angle (see my picture above). I am just wondering if the hole could have been drilled wrong that day on the assembly line...

demi · 12-12-2004, 01:02 PM

yea CrustySarge, it's a factory A/C truck. I just cleaned everything up to get it working better.

crustysarge · 12-12-2004, 02:23 PM

Interesting, what year Demi? Strange the holes would be so different. After much trial and tribulation (and some help from the wife) I got it lokking better. I bent the small spring loaded shaft downward just a bit and that helped get the valve out of the firewall a little straighter. Not perfect but not binding and rides on the grovved tab. I put anti sieze on everything that moves.

demi · 12-12-2004, 02:29 PM

My truck is a '69. Good to hear you got yours to work. As long as it functions properly you're good to go.

12-11-2004, 12:00 PM	#1
crustysarge Registered User Join Date: Mar 2004 Location: Aviano, Italy Posts: 221	Fresh air valve and vacuum diaphragm install mess!!! OK, I recently discovered the fresh air plenum valve was broke and the diaphragm was ruptured. I ordered new ones and now can't get it put back in correctly. Now, the old valve was broke where it connected to the shaft so I don't know how it sit in the firewall hole. I had to bend the crap out the bracket to get the shaft to line up, the tab that the shaft is supposed to ride on had to be bent down almost flush with the bracket. I linked a couple of pictures to see if someone can give me some advice. I left it alone before I broke it...The valve will not close all the way as it is now. I also took a shot of where the valve shaft sits when the white plastic mount is screwed on the firewall. Think the hole is off? What about the replacement shaft hole, could it be drilled wrong? http://img.photobucket.com/albums/v6...e/CIMG0334.jpg http://img.photobucket.com/albums/v6...e/CIMG0335.jpg http://img.photobucket.com/albums/v6...e/CIMG0336.jpg http://img.photobucket.com/albums/v6...e/CIMG0337.jpg http://img.photobucket.com/albums/v6...e/CIMG0338.jpg http://img.photobucket.com/albums/v6...e/CIMG0339.jpg Last edited by crustysarge; 12-11-2004 at 01:58 PM.

12-11-2004, 02:07 PM	#2
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	See if this will help. Attached Images __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-11-2004, 02:15 PM	#3
demi Registered User Join Date: Sep 2003 Location: Arizona Posts: 305	Here are two reference pics on how mine is hooked up. Hope this helps. demi

12-12-2004, 04:29 AM	#4
crustysarge Registered User Join Date: Mar 2004 Location: Aviano, Italy Posts: 221	Thanks for the close up shot Demi. I wish mine looked like that! My problem is the shaft is coming out of the firewall at a downward angle, that is why I had to bend the tab down. It is now daylight here in Itlay so I am headed out to investigate. Demi, is yours a factory air? The reason I ask is because I see the white nylon plate is appears to be perpendicular to the firewall and mine is installed at an angle (see my picture above). I am just wondering if the hole could have been drilled wrong that day on the assembly line...

12-12-2004, 01:02 PM	#5
demi Registered User Join Date: Sep 2003 Location: Arizona Posts: 305	yea CrustySarge, it's a factory A/C truck. I just cleaned everything up to get it working better.

12-12-2004, 02:23 PM	#6
crustysarge Registered User Join Date: Mar 2004 Location: Aviano, Italy Posts: 221	Interesting, what year Demi? Strange the holes would be so different. After much trial and tribulation (and some help from the wife) I got it lokking better. I bent the small spring loaded shaft downward just a bit and that helped get the valve out of the firewall a little straighter. Not perfect but not binding and rides on the grovved tab. I put anti sieze on everything that moves.

12-12-2004, 02:29 PM	#7
demi Registered User Join Date: Sep 2003 Location: Arizona Posts: 305	My truck is a '69. Good to hear you got yours to work. As long as it functions properly you're good to go.



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