Home » Public Forums » GMCnet » Heater Shut Off Valves Revisited
| Heater Shut Off Valves Revisited [message #258580] |
Tue, 12 August 2014 10:34  |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
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I'm getting ready to install a set of ball valves to stop coolant flow to and from my heater.
After thinking about it for a bit - I wonder - doesn't the dashboard controlled valve in the heater lines do the same thing ??
(I'm referring to the temperature control lever on the AC / heater / defrost control box.)
Thanks for your thoughts and comments.
Steve W
1973 23'
Southern California
Steve W
1973 : 23'
Southern California
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| Re: Heater Shut Off Valves Revisited [message #258582 is a reply to message #258580] |
Tue, 12 August 2014 10:44  |
C Boyd
Messages: 2629
Registered: April 2006
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Yes Sir it sure does.
SteveW wrote on Tue, 12 August 2014 11:34I'm getting ready to install a set of ball valves to stop coolant flow to and from my heater.
After thinking about it for a bit - I wonder - doesn't the dashboard controlled valve in the heater lines do the same thing ??
(I'm referring to the temperature control lever on the AC / heater / defrost control box.)
Thanks for your thoughts and comments.
Steve W
1973 23'
Southern California
C. Boyd
76 Crestmont
East Tennessee
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| Re: Heater Shut Off Valves Revisited [message #258583 is a reply to message #258580] |
Tue, 12 August 2014 11:04 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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SteveW wrote on Tue, 12 August 2014 08:34I'm getting ready to install a set of ball valves to stop coolant flow to and from my heater.
After thinking about it for a bit - I wonder - doesn't the dashboard controlled valve in the heater lines do the same thing ??
(I'm referring to the temperature control lever on the AC / heater / defrost control box.)
Thanks for your thoughts and comments.
Steve W
1973 23'
Southern California
Yes it does but they can leak a bit as they age.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258589 is a reply to message #258580] |
Tue, 12 August 2014 12:39 |
powerjon
Messages: 2446
Registered: January 2004
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Yes, the heater valve does control the flow to the heater but it can and does leak and that is why we add the shutoff valve for positive shutoff. You only need to install ONE valve and not TWO. Pick a hose either in or out and put in your valve, once you shut it there is no flow thru the heater.
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
On Aug 12, 2014, at 11:34 AM, Steve Weinstock wrote:
> I'm getting ready to install a set of ball valves to stop coolant flow to and from my heater.
>
> After thinking about it for a bit - I wonder - doesn't the dashboard controlled valve in the heater lines do the same thing ??
>
> (I'm referring to the temperature control lever on the AC / heater / defrost control box.)
>
> Thanks for your thoughts and comments.
>
> Steve W
> 1973 23'
> Southern California
>
>
> _______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Shut Off Valves Revisited [message #258594 is a reply to message #258588] |
Tue, 12 August 2014 13:34 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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USAussie wrote on Tue, 12 August 2014 12:36Yes they do.
Go take a look at is and you'll notice it is probably a plastic body and has a metal butterfly to control the flow. In all
probability it doesn't stop the flow of hot water from the engine 100%. The GMC dash air system in your '73 is lame at best (77-78
are the only years that are decent) and having warm air in the A/C "box" doesn't help.
Plus if you should suffer a heater core failure you have a problem because you can't shut off the water to both the inlet and outlet
of the heater.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: Steve Weinstock
I'm getting ready to install a set of ball valves to stop coolant flow to and from my heater.
After thinking about it for a bit - I wonder - doesn't the dashboard controlled valve in the heater lines do the same thing ??
(I'm referring to the temperature control lever on the AC / heater / defrost control box.)
Thanks for your thoughts and comments.
Steve
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also when there is no vacuum, i.e. engine stopped or at WOT the valve will open.
A ball valve will stay closed
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258640 is a reply to message #258582] |
Tue, 12 August 2014 20:44 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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Steve,
Which heater, hot water or the front cab heater?
On Tue, Aug 12, 2014 at 9:45 AM, Charles Boyd
wrote:
> Yes Sir it sure does.
>
>
>
>
> SteveW wrote on Tue, 12 August 2014 11:34
>> I'm getting ready to install a set of ball valves to stop coolant flow
> to and from my heater.
>>
>> After thinking about it for a bit - I wonder - doesn't the dashboard
> controlled valve in the heater lines do the same thing ??
>>
>> (I'm referring to the temperature control lever on the AC / heater /
> defrost control box.)
>>
>> Thanks for your thoughts and comments.
>>
>> Steve W
>> 1973 23'
>> Southern California
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: Heater Shut Off Valves Revisited [message #258643 is a reply to message #258580] |
Tue, 12 August 2014 21:08 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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SteveW wrote on Tue, 12 August 2014 09:34I'm getting ready to install a set of ball valves to stop coolant flow to and from my heater.
After thinking about it for a bit - I wonder - doesn't the dashboard controlled valve in the heater lines do the same thing ??
(I'm referring to the temperature control lever on the AC / heater / defrost control box.)
Thanks for your thoughts and comments.
Steve W
1973 23'
Southern California
It does and works very well without having to screw around and get into and out of your coach and forget in what position you left it. If yours isn't working, they are easy to find and will last you for another 20 years.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Heater Shut Off Valves Revisited [message #258653 is a reply to message #258643] |
Tue, 12 August 2014 21:58 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Early on in my ownership of the coach, I replaced all the hoses and the vacuum operated valve to the heater core. The PO had installed a ball valve and I left it in as well. In my experience, the AC blows colder if I shut off the manual ball valve, leading me to believe that the vacuum operated valve does NOT completely cut off the flow of hot water to the heater core.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Heater Shut Off Valves Revisited [message #258663 is a reply to message #258580] |
Wed, 13 August 2014 02:32 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I do not know why you need a "set" of ball valves. One will do the trick. If you take a look inside of the standard heater control valve used by GM you will see that is never turns off all the way. The is a hole in the butterfly and the butterfly does not touch the sides. I have both installed in series in mine. I turn the ball valve off in the spring and back on in the fall. Only once ever have I had to stop along the road to turn it back on.
That complex bypass valve on ebay seems like over kill to me since heater core failures are rare. Heater hose failures at connections are probably more common. If you install a bypass on the heater you add more connections. How about a bypass on the trans oil cooler or the engine oil cooler. I suggest that they probably fail at the same rate as the heater core.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258676 is a reply to message #258640] |
Wed, 13 August 2014 08:26 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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G'day,
Double Trouble and The Blue Streak both have two valves on the dash heater and two valves on the hoses that go back to the Atwood
electric water heater. I installed two on the dash heater in case the heater core failed and two on the water heater in case the
hoses failed.
I AM PEDANTIC!
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Bruce Hart
Sent: Tuesday, August 12, 2014 8:44 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Heater Shut Off Valves Revisited
Steve,
Which heater, hot water or the front cab heater?
On Tue, Aug 12, 2014 at 9:45 AM, Charles Boyd
wrote:
> Yes Sir it sure does.
>
>
>
>
> SteveW wrote on Tue, 12 August 2014 11:34
>> I'm getting ready to install a set of ball valves to stop coolant flow
> to and from my heater.
>>
>> After thinking about it for a bit - I wonder - doesn't the dashboard
> controlled valve in the heater lines do the same thing ??
>>
>> (I'm referring to the temperature control lever on the AC / heater /
> defrost control box.)
>>
>> Thanks for your thoughts and comments.
>>
>> Steve W
>> 1973 23'
>> Southern California
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Bruce Hart
1976 Palm Beach
Milliken, Co
GMC=Got More Class
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258678 is a reply to message #258663] |
Wed, 13 August 2014 08:20 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Steve,
I am also with Ken on this on using the bypass style valve. Don’t make it any more complicated as KISS is best! You can get replacements at most auto part stores. If you want an almost factory like unit get the O’Reilly unit which is like the original Z78 parts book PN 494192.
or
http://goo.gl/kFQihY
You can also use these part numbers that are more inexpensive.
Advance Auto PN 74612
or
http://goo.gl/SRhLBz
AutoZone PN 74612
O’Reilly PN74612
You can also get the GMC Chevy dealer replacement AC Delco PN 12515169 at about $30 too.
JR Wright
78 Buskirk Stretch
75 Avion
Michigan
On Aug 13, 2014, at 3:33 AM, Ken Burton wrote:
> I do not know why you need a "set" of ball valves. One will do the trick. If you take a look inside of the standard heater control valve used by GM
> you will see that is never turns off all the way. The is a hole in the butterfly and the butterfly does not touch the sides. I have both installed
> in series in mine. I turn the ball valve off in the spring and back on in the fall. Only once ever have I had to stop along the road to turn it back
> on.
>
> That complex bypass valve on ebay seems like over kill to me since heater core failures are rare. Heater hose failures at connections are probably
> more common. If you install a bypass on the heater you add more connections. How about a bypass on the trans oil cooler or the engine oil cooler. I
> suggest that they probably fail at the same rate as the heater core.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258710 is a reply to message #258678] |
Wed, 13 August 2014 11:57 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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The OEM valve, as has been reported, does not completely stop hot water flow
to the heater core -- a bad thing with marginal air conditioning. "Back
When" I had a new 40' Safari, we had a similar setup. It was easily
corrected by installing one of those "H" valves, which directs the flow
back to the engine, bypassing the heater core.
Because I'd lost my known source for "H" valves, when I found the GMC's
setup one-sided, I also added a manual ball valve. Were I going to refresh
my hoses again, I'd install one of those H valves.
JWID,
Ken H.
On Wed, Aug 13, 2014 at 9:20 AM, John Wright wrote:
> Steve,
> I am also with Ken on this on using the bypass style valve. Don’t make it
> any more complicated as KISS is best! You can get replacements at most
> auto part stores. If you want an almost factory like unit get the O’Reilly
> unit which is like the original Z78 parts book PN 494192.
>
> http://www.oreillyauto.com/site/c/detail/MOT0/YG136.oap?ck=Search_yg136_-1_3436&keyword=yg136
>>
> or
> http://goo.gl/kFQihY
>
> ...
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Heater Shut Off Valves Revisited [message #258732 is a reply to message #258653] |
Wed, 13 August 2014 14:43 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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Carl S. wrote on Tue, 12 August 2014 20:58Early on in my ownership of the coach, I replaced all the hoses and the vacuum operated valve to the heater core. The PO had installed a ball valve and I left it in as well. In my experience, the AC blows colder if I shut off the manual ball valve, leading me to believe that the vacuum operated valve does NOT completely cut off the flow of hot water to the heater core.
They may be all over the map. I put a new one in and I think it was for a Ford since all I cared about where the fittings. Many times in the fall, even in AZ there are times when I need heat in the morning and then full AC just a few hours later, so I wanted to keep it "automatic"
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258734 is a reply to message #258710] |
Wed, 13 August 2014 15:10 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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Ken Henderson wrote on Wed, 13 August 2014 10:57The OEM valve, as has been reported, does not completely stop hot water flow
to the heater core -- a bad thing with marginal air conditioning. "Back
When" I had a new 40' Safari, we had a similar setup. It was easily
corrected by installing one of those "H" valves, which directs the flow
back to the engine, bypassing the heater core.
Because I'd lost my known source for "H" valves, when I found the GMC's
setup one-sided, I also added a manual ball valve. Were I going to refresh
my hoses again, I'd install one of those H valves.
JWID,
Ken H.
On Wed, Aug 13, 2014 at 9:20 AM, John Wright wrote:
> Steve,
> I am also with Ken on this on using the bypass style valve. Don't make it
> any more complicated as KISS is best! You can get replacements at most
> auto part stores. If you want an almost factory like unit get the O'Reilly
> unit which is like the original Z78 parts book PN 494192.
>
> http://www.oreillyauto.com/site/c/detail/MOT0/YG136.oap?ck=Search_yg136_-1_3436&keyword=yg136
>>
> or
> http://goo.gl/kFQihY
>
> ...
>
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Ken, I'm curious about the fact that they don't close all the way. I figure if anyone has ever tested one it would be you. Originally I just put my hand on the hose and it was warm with the valve closed. I put in a new one and the hose was cold after that. That's the amount of testing I have done.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Heater Shut Off Valves Revisited [message #258761 is a reply to message #258734] |
Wed, 13 August 2014 19:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Bob,
No, I have not opened a GMC OEM valve to see its configuration. But I
have, over these many years seen the insides of a lot of similar ones. All
of those had a butterfly valve with no precision seat; most didn't even
have a "seat", they just rested against the inside of the tube and were not
tightly fitted -- they just restricted flow, not eliminated it. Some of
them, as someone else recently mentioned, even had a hole in the butterfly,
for what reason I don't know and can only speculate. I do know that my GMC
OEM allowed some flow when I tested by hand as you did. Not expecting any
of them to eliminate flow, I just put in the ball valve. It's rare that I
have to turn its handle. Frankly, if I ever need to turn it OPEN, I should
be headed south anyway. :-)
Ken H.
On Wed, Aug 13, 2014 at 4:11 PM, Bob de Kruyff wrote:
> Ken, I'm curious about the fact that they don't close all the way. I
> figure if anyone has ever tested one it would be you. Originally I just put
> my
> hand on the hose and it was warm with the valve closed. I put in a new
> one and the hose was cold after that. That's the amount of testing I have
> done.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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