GMCforum
For enthusiast of the Classic GMC Motorhome built from 1973 to 1978. A web-based mirror of the GMCnet mailing list.
Home » Public Forums » GMCnet » [GMCnet] Vacuum hose routing diagram
[GMCnet] Vacuum hose routing diagram [message #179314] Mon, 06 August 2012 23:07 Go to next message
RicksGMC is currently offline  RicksGMC   United States
Messages: 145
Registered: May 2012
Karma: 0
Senior Member
Is there a diagram out there that shows the correct routing and connections for the engine vacuum lines?
I was looking under the hood and noticed a vacuum "chamber" mounted to the drivers side of heater box (?) just to the right of the washer fluid container, but there are no hoses or anything attached to it ?????
Engine appears to be running fine, I don't have a vacuum gauge (yet!) so I have not checked vacuum levels.



Rick Drummond
Prior Lake MN
1974 (re-)Painted Desert 26'
TZE064V100077
Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
Email: RandTs.GMC@gmail.com
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Rick Rick&Tammy Drummond Prior Lake MN '74 (re)Painted Desert

Report message to a moderator

Re: [GMCnet] Vacuum hose routing diagram [message #179330 is a reply to message #179314] Tue, 07 August 2012 06:56 Go to previous messageGo to next message
Mr ERFisher is currently offline  Mr ERFisher   United States
Messages: 7117
Registered: August 2005
Karma: 2
Senior Member
here are a few
http://goo.gl/fubEQ

gene


On Mon, Aug 6, 2012 at 9:07 PM, Rick <randts.gmc@gmail.com> wrote:

> Is there a diagram out there that shows the correct routing and
> connections for the engine vacuum lines?
> I was looking under the hood and noticed a vacuum "chamber" mounted to the
> drivers side of heater box (?) just to the right of the washer fluid
> container, but there are no hoses or anything attached to it ?????
> Engine appears to be running fine, I don't have a vacuum gauge (yet!) so I
> have not checked vacuum levels.
>
>
>
> Rick Drummond
> Prior Lake MN
> 1974 (re-)Painted Desert 26'
> TZE064V100077
> Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
> Email: RandTs.GMC@gmail.com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>



--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Report message to a moderator

Re: [GMCnet] Vacuum hose routing diagram [message #179369 is a reply to message #179314] Tue, 07 August 2012 11:06 Go to previous messageGo to next message
A Hamilto is currently offline  A Hamilto   United States
Messages: 4508
Registered: April 2011
Karma: 39
Senior Member
RicksGMC wrote on Mon, 06 August 2012 23:07

Is there a diagram out there that shows the correct routing and connections for the engine vacuum lines?
I was looking under the hood and noticed a vacuum "chamber" mounted to the drivers side of heater box (?) just to the right of the washer fluid container, but there are no hoses or anything attached to it ?????
Engine appears to be running fine, I don't have a vacuum gauge (yet!) so I have not checked vacuum levels.



Rick Drummond
Prior Lake MN
1974 (re-)Painted Desert 26'
TZE064V100077
Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
Email: RandTs.GMC@gmail.com
That's the vacuum canister for the heater/AC actuators. If everything is working on the heater/AC, maybe a PO installed another one somewhere else. I suppose one could bypass it by just splicing the input hose to the output hose. Not sure how well the heater/AC acuators would work then?

Report message to a moderator

Re: [GMCnet] Vacuum hose routing diagram [message #180566 is a reply to message #179369] Thu, 16 August 2012 21:51 Go to previous messageGo to next message
RicksGMC is currently offline  RicksGMC   United States
Messages: 145
Registered: May 2012
Karma: 0
Senior Member
Investigated the vacuum lines and sure enough the PO had bypassed the vacuum chamber completely. Hooked up my vacuum tester and checked all the lines and none of them would hold vacuum!
Ended up replacing all the vacuum hoses (one at a time) and reconnecting the vacuum chamber, retested the lines and all held perfectly. It's amazing the thing even ran.
My AC and cruise control never have worked for me, I'm curious if this will help those issues too.

Thanks for all the photo's, suggestions, and advise!

Rick Drummond
Prior Lake MN
1974 (re-)Painted Desert 26'
TZE064V100077
Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
Email: RandTs.GMC@gmail.com

On Aug 7, 2012, at 11:06 AM, A. <markbb1@netzero.com> wrote:

>
>
> RicksGMC wrote on Mon, 06 August 2012 23:07
>> Is there a diagram out there that shows the correct routing and connections for the engine vacuum lines?
>> I was looking under the hood and noticed a vacuum "chamber" mounted to the drivers side of heater box (?) just to the right of the washer fluid container, but there are no hoses or anything attached to it ?????
>> Engine appears to be running fine, I don't have a vacuum gauge (yet!) so I have not checked vacuum levels.
>>
>>
>>
>> Rick Drummond
>> Prior Lake MN
>> 1974 (re-)Painted Desert 26'
>> TZE064V100077
>> Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
>> Email: RandTs.GMC@gmail.com
> That's the vacuum canister for the heater/AC actuators. If everything is working on the heater/AC, maybe a PO installed another one somewhere else. I suppose one could bypass it by just splicing the input hose to the output hose. Not sure how well the heater/AC acuators would work then?
> --
> '73 23' CanyonLands
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Rick Rick&Tammy Drummond Prior Lake MN '74 (re)Painted Desert

Report message to a moderator

Re: [GMCnet] Vacuum hose routing diagram [message #180574 is a reply to message #180566] Thu, 16 August 2012 22:31 Go to previous messageGo to next message
A Hamilto is currently offline  A Hamilto   United States
Messages: 4508
Registered: April 2011
Karma: 39
Senior Member
RicksGMC wrote on Thu, 16 August 2012 21:51

Investigated the vacuum lines and sure enough the PO had bypassed the vacuum chamber completely. Hooked up my vacuum tester and checked all the lines and none of them would hold vacuum!
Ended up replacing all the vacuum hoses (one at a time) and reconnecting the vacuum chamber, retested the lines and all held perfectly. It's amazing the thing even ran.
My AC and cruise control never have worked for me, I'm curious if this will help those issues too.

Thanks for all the photo's, suggestions, and advise!

Rick Drummond
Prior Lake MN
1974 (re-)Painted Desert 26'
TZE064V100077
Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
I think the '74s have a recirculate door that changes the mix from 100% outside air to 20% outside air and 80% recirculated. If connecting that canister enables the recirc door to function (assuming it wasn't working before), you might get a little better AC performance. Also, you might need to add some refrigerant to the system. Some say you shouldn't have high expectations of the dash AC on a '74 no matter what. Don't know if what you did will affect the cruise control.

Report message to a moderator

Re: [GMCnet] Vacuum hose routing diagram [message #180608 is a reply to message #180566] Fri, 17 August 2012 07:56 Go to previous message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
Chances are your cruise and AC may now work fine !! Good find Rick !!

Ray


Ray & Lisa
78 Royale "Great Lakes Eagle"
Center Kitchen TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Rick <randts.gmc@gmail.com>
To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
Sent: Thu, August 16, 2012 9:51:13 PM
Subject: Re: [GMCnet] Vacuum hose routing diagram

Investigated the vacuum lines and sure enough the PO had bypassed the vacuum
chamber completely. Hooked up my vacuum tester and checked all the lines and
none of them would hold vacuum!
Ended up replacing all the vacuum hoses (one at a time) and reconnecting the
vacuum chamber, retested the lines and all held perfectly. It's amazing the
thing even ran.
My AC and cruise control never have worked for me, I'm curious if this will help
those issues too.

Thanks for all the photo's, suggestions, and advise!

Rick Drummond
Prior Lake MN
1974 (re-)Painted Desert 26'
TZE064V100077
Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
Email: RandTs.GMC@gmail.com

On Aug 7, 2012, at 11:06 AM, A. <markbb1@netzero.com> wrote:

>
>
> RicksGMC wrote on Mon, 06 August 2012 23:07
>> Is there a diagram out there that shows the correct routing and connections for
>>the engine vacuum lines?
>> I was looking under the hood and noticed a vacuum "chamber" mounted to the
>>drivers side of heater box (?) just to the right of the washer fluid container,
>>but there are no hoses or anything attached to it ?????
>> Engine appears to be running fine, I don't have a vacuum gauge (yet!) so I have
>>not checked vacuum levels.
>>
>>
>>
>> Rick Drummond
>> Prior Lake MN
>> 1974 (re-)Painted Desert 26'
>> TZE064V100077
>> Photos: http://www.gmcmhphotos.com/photos/u18085-r-drummond.html
>> Email: RandTs.GMC@gmail.com
> That's the vacuum canister for the heater/AC actuators. If everything is
>working on the heater/AC, maybe a PO installed another one somewhere else. I
>suppose one could bypass it by just splicing the input hose to the output hose.
>Not sure how well the heater/AC acuators would work then?
> --
> '73 23' CanyonLands
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431

Report message to a moderator

Previous Topic: EFI for Onan?
Next Topic: Re: [GMCnet] EFI for Onan?
Goto Forum:
  


Current Time: Tue Mar 18 00:02:05 CDT 2025

Total time taken to generate the page: 0.00844 seconds
.:: Contact :: Home ::.

Powered by: FUDforum 3.1.1.
Copyright ©2001-2021 FUDforum Bulletin Board Software