Heater core shut off valve - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SCOTI · 04-06-2021, 11:48 AM

Quote:

Originally Posted by RichardJ

The first image below from Summit looks very close to the cross-over used with 60's 289 fnords. The other images, also on Summit are from 4 Seasons that have internal valves. 4 seasons has a variety of manual cross-over styles, also shown in Summit.

That's the early version of it. Thanks for adding that to the info.

The unit I've seen is a billet piece. Very clean unit. I'll post up the info as soon as I can access it but it's basically just a higher-end (and more expensive) version of the early variations in your provided link/s.

pwdcougar · 04-06-2021, 12:51 PM

Quote:

Originally Posted by SCOTI

Apparently some later model vehicles require flow on the path to the heater core or suffer cavitation issues. I recently learned this & was not aware. These set-ups actually have a bypass that stops flow to the heater core (similar to these cut-off valves) yet allows for the loop to still circulate.

I learned about them on various LS swaps I've seen on the web.

Yes I found this out when I bypassed the heater core on a 97 Buick Century. The heater core is an integral part of the cooling system. I installed a bypass valve that was for a Ford Ranger

SCOTI · 04-06-2021, 01:52 PM

Quote:

Originally Posted by pwdcougar

Yes I found this out when I bypassed the heater core on a 97 Buick Century. The heater core is an integral part of the cooling system. I installed a bypass valve that was for a Ford Ranger

I never gave these much thought.

I had a primitive bypass set-up (as in using what I had available for free vs spending money for something that may not impact my issue) for my 74swb @ one point. I was struggling w/heat soak on the a/c & wanted to see if blocking the hot-water flow to the heater core helped. I built a similar, simple hand valve set-up as it's what I had available for testing.

I knew there were early OE versions of a vacuum/temp actuated bypass valve (from GM) available but wasn't going to spend the money for one just to find out it didn't make a difference for my needs.

Killer Bee · 04-06-2021, 02:06 PM

wait... what?? there's a valve that does this?

**Richard** · 04-06-2021, 02:21 PM

I believe the two types of vacuum operated valves for 67-72 trucks are different. If I recall correctly the early one without bracket is normally closed and later one with bracket is normally open. Both could be used together to create a bypass.

Andy4639 · 04-06-2021, 08:09 PM

I had a hard time getting mine to burb when I installed it. I finally had the front end jacked up and took the 2 small steam ports loose on the front of the engine. That seemed to do it. Haven't had any more issues since. That was back in 2014. That I know of any way the truck runs cool even with the AC on.

Mav · 11-09-2023, 01:26 AM

My 70 K10 is non a/c so I installed valve like Grumpy showed pic of. There is a vacuum operated valve for a/c trucks, but cant find a valve for mine, they dont make one? Or does heat lever control something other than a valve? thanks!

**70STOVEBOLT** · 11-09-2023, 02:19 PM

Heat lever only controls a blend door on non-a/c trucks.

**Rust_never_sleeps** · 11-09-2023, 05:03 PM

If I paint my vise-grips silver, does that count as billet?

Mav · 11-09-2023, 05:07 PM

Thanks, I wont pull box off firewall just to see whats there. The other problem is keeping fan switch adjusted, will get it right, but in a few hundred miles it gets finicky again, blue loctite on screws? Thanks again for reply!

ZEKE68 · 11-09-2023, 08:15 PM

I screwed a stainless steel body, teflon seat ball valve into the intake manifold, and run the hose from it, with an elbow.

Mav · 11-09-2023, 08:36 PM

Anytime you can replace a gate valve with a ball, good idea.

04-06-2021, 02:06 PM	#29
Killer Bee Registered User Join Date: Jan 2016 Location: Barber City, CA Posts: 4,728	Re: Heater core shut off valve wait... what?? there's a valve that does this? __________________ *I started out with nothing - and I still have most of it*

04-06-2021, 02:21 PM	#30
Richard Senior Member Join Date: Dec 1999 Location: Southern California Posts: 2,696	Re: Heater core shut off valve I believe the two types of vacuum operated valves for 67-72 trucks are different. If I recall correctly the early one without bracket is normally closed and later one with bracket is normally open. Both could be used together to create a bypass. __________________ Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746

04-06-2021, 08:09 PM	#31
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,936	Re: Heater core shut off valve I had a hard time getting mine to burb when I installed it. I finally had the front end jacked up and took the 2 small steam ports loose on the front of the engine. That seemed to do it. Haven't had any more issues since. That was back in 2014. That I know of any way the truck runs cool even with the AC on. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

11-09-2023, 01:26 AM	#32
Mav Registered User Join Date: Jun 2016 Location: Richland Or. Posts: 101	Re: Heater core shut off valve My 70 K10 is non a/c so I installed valve like Grumpy showed pic of. There is a vacuum operated valve for a/c trucks, but cant find a valve for mine, they dont make one? Or does heat lever control something other than a valve? thanks!

11-09-2023, 02:19 PM	#33
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 6,212	Re: Heater core shut off valve Heat lever only controls a blend door on non-a/c trucks. __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Power windows Power Locks Coming soon: EFI 2015 Silverado 1500 LS 4.3/6L80/3.23

11-09-2023, 05:03 PM	#34
Rust_never_sleeps Senior Member Join Date: Jun 2022 Location: San Ramon,CA Posts: 398	Re: Heater core shut off valve If I paint my vise-grips silver, does that count as billet?

11-09-2023, 05:07 PM	#35
Mav Registered User Join Date: Jun 2016 Location: Richland Or. Posts: 101	Re: Heater core shut off valve Thanks, I wont pull box off firewall just to see whats there. The other problem is keeping fan switch adjusted, will get it right, but in a few hundred miles it gets finicky again, blue loctite on screws? Thanks again for reply!

11-09-2023, 08:15 PM	#36
ZEKE68 Registered User Join Date: Jul 2012 Location: Space Coast, Florida Posts: 403	Re: Heater core shut off valve I screwed a stainless steel body, teflon seat ball valve into the intake manifold, and run the hose from it, with an elbow. __________________ 1968 SWB Step Side, Big Block, 4L80E , Running!

11-09-2023, 08:36 PM	#37
Mav Registered User Join Date: Jun 2016 Location: Richland Or. Posts: 101	Re: Heater core shut off valve Anytime you can replace a gate valve with a ball, good idea.



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