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Old 04-03-2021, 09:45 PM   #1
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Heater core shut off valve

Hey everyone!
I read somewhere on here that someone had put a valve on their heater core inlet hose. So that the hot water would not circulate in the heater core.
I'm interested in this fix as summer approaches.
My heater shut off is worn out and allows hot air into the cab all the time.

My question: Will adding a valve in my system cause any problems?
Any advice is much appreciated.
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Old 04-03-2021, 09:51 PM   #2
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Thumbs up Re: Heater core shut off valve

I have run them for years with no problems. If you have AC in the truck it's worth every penny. When I installed the one in my 71 C 10 I got 5* more out of my AC.

Pictures are of the one in my Ramp truck.
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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.
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Old 04-03-2021, 09:59 PM   #3
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Re: Heater core shut off valve

I've had one on my 69 Cougar for 20 years with no problems. I used a solder connection type brass ball valve and soldered on a couple inches of copper pipe and put two clamps on each side.
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Old 04-03-2021, 10:08 PM   #4
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Re: Heater core shut off valve

https://www.autozone.com/cooling-hea...E&gclsrc=aw.ds
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Old 04-03-2021, 10:44 PM   #5
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Re: Heater core shut off valve

So which line to you put it on, from the block or the Radiator?

I ask since the A/C shop put one on for me but it shuts off from the Radiator. Seems it would work better from the block side, in front of the vacuum control shut off valve.
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Old 04-04-2021, 12:18 AM   #6
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Re: Heater core shut off valve

Put the valve on the hose from the engine -- that is the heat source. The hose to the radiator is for water exiting the heater core.
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Old 04-04-2021, 02:03 AM   #7
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Re: Heater core shut off valve

The vacuum shut off valve should be standard on an A/C truck. Basically does not matter what hose it is installed in, will stop the flow, in the heat side does make make sense.
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Old 04-04-2021, 03:57 AM   #8
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Re: Heater core shut off valve

Ok, laugh at me...
This is to reduce hotness in the cab in the summer? I've seen them in a few trucks and wondered...
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Old 04-04-2021, 07:08 AM   #9
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Re: Heater core shut off valve

Quote:
Originally Posted by Stocker View Post
Put the valve on the hose from the engine -- that is the heat source. The hose to the radiator is for water exiting the heater core.
That is what I was thinking too, it would make more sense for the shut off to be on source side. I'd just figured the A/C guy knew something different.

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The vacuum shut off valve should be standard on an A/C truck. Basically does not matter what hose it is installed in, will stop the flow, in the heat side does make make sense.
Yes, understand it is standard and I do have a new one but my understanding they kind of suck - so that is why I asked for a manual shut off value when the A/C was being fixed & upgraded.

Now I need to decide when/if to move it over to the inlet/engine source side. It's one of those things I look at and scratch my head about .... "is that right?". At some point I suppose I'll just do it because it will get on my nerves LOL

Edit: NM my hoses are actually correct.

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Originally Posted by franken View Post
Ok, laugh at me...
This is to reduce hotness in the cab in the summer? I've seen them in a few trucks and wondered...
That pretty much it, to 100% stop hot water flow in the cab. If any hot water flow gets to the coil it affects the efficiency of the A/C (and I'd image any cool air you are trying to get if you haven't A/C).
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Old 04-04-2021, 07:18 AM   #10
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Re: Heater core shut off valve

Quote:
Originally Posted by Grumpy old man View Post
Grumpy, I assume that is more like a OEM cut off?
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Old 04-04-2021, 08:05 AM   #11
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Re: Heater core shut off valve

Quote:
Originally Posted by Rich72C10 View Post
Grumpy, I assume that is more like a OEM cut off?
They've been around forever , it's inexpensive at around $10.00 at your local parts house and installed in minutes .

And they look good , Not like you stole the plumbing off your grandmothers water heater !
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Old 04-04-2021, 08:30 AM   #12
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Re: Heater core shut off valve

ya, I am pretty sure you (or someone else) commented on one of my post where the A/C guy installed a setup much like Andy's. Which is exactly the same cut off valve I installed on my water heater LOL!
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Old 04-04-2021, 08:46 AM   #13
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Re: Heater core shut off valve

Hey , it's your truck use whatever makes you happy .
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Old 04-04-2021, 09:36 AM   #14
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Re: Heater core shut off valve

Well, I didnít do it and I can say I was all that happy. But now I am, since I just changed it.
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Old 04-04-2021, 10:07 AM   #15
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Re: Heater core shut off valve

Really appreciate the posts, stories, and replies.
Always learning from you all here.
Happy Easter!
Now I'm going to go shut off the hot water flow!
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Old 04-04-2021, 10:36 AM   #16
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Re: Heater core shut off valve

Your post helped me as much as you External - got me motivated to sort mine out! I even did a bit more rerouting and the inlet line isn't touching any of the A/C lines now. I also cut down the water reserve line as it was like a mile long - so it's nice and tidy all around on that side with water lines.

Have fun - the more you visit these forums the more you learn you need to do to your truck LOL!
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Old 04-04-2021, 12:38 PM   #17
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Re: Heater core shut off valve

If your looking for original GM look, early 60's AC cars ( I would start with Cadillac or Buick or Olds) had a vacuum shut off valve.
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Old 04-04-2021, 01:41 PM   #18
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Re: Heater core shut off valve

I installed Vortec heads, which are lacking a coolant hole that older heads have for recirculation before the thermostat opens. I am relying on my heater core for recirculation, so installing a manual shutoff valve to the heater core would be a bad move in my case. I would have to install a thermostat bypass hose between the water pump and front of the intake manifold. I really don't like how those bypass hoses look. I will have to do that eventually though if I add AC to my truck.
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Old 04-04-2021, 08:23 PM   #19
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Re: Heater core shut off valve

Well I was going to post something but I want since it's Easter Sunday.
Both my trucks perform well and I'll just leave it at that.
There is always someone.
Good luck with it. I hope you figure it out.
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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.
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Old 04-04-2021, 09:49 PM   #20
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Re: Heater core shut off valve

I hope I didn't say anything that upset you. I was talking about the little hose people have to add to the front of the intake manifold when running Vortec heads on trucks with AC.
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Old 04-06-2021, 10:02 AM   #21
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Re: Heater core shut off valve

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.
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Old 04-06-2021, 10:27 AM   #22
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Re: Heater core shut off valve

Can this be done on a non-ac truck ?
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Old 04-06-2021, 10:46 AM   #23
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Question Re: Heater core shut off valve

Quote:
Originally Posted by 71longbed-brew View Post
Can this be done on a non-ac truck ?
My Ramp truck isn't AC truck and it cuts the heat off totally in the summer which helps a lot.

SCOTI,
I have the valve in my 71 C 10 with the vacuum valve in the other line with the LS 6.0 and not had any problems before. Can you share some links on the problems are symptoms of it.
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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.

Last edited by Andy4639; 04-06-2021 at 10:52 AM.
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Old 04-06-2021, 10:52 AM   #24
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Re: Heater core shut off valve

Quote:
Originally Posted by Andy4639 View Post
My Ramp truck isn't AC truck and it cuts the heat off totally in the summer which helps a lot.

SCOTI,
I have the valve in my 71 C 10 with the vacuum valve in the other line with the LS 6.0 and not had any problems before. Can you share some links on the problems are symptoms of it.
I actually tried to copy & post the link/info here but apparently the site where it is (where I learned of it) is having issues. I'll post up the info once I can access it. Apparently some LS cooling systems are harder than others to properly purge air & a contributing factor can be the coolant to heater core loop.
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.
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Old 04-06-2021, 11:19 AM   #25
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Re: Heater core shut off valve

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.
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