1972 Heat is always on!

[72rookie]

My 1972 LWB is always blowing heat out the vents. I got the truck this winter so it wasnt a big deal when I was cruising around but now that it is summer it is not fun to stick to the vinyl seats. Any suggestions form any body would be a great help.

[dznucks]

is your fan constantly blowing? or is it just hot air coming out.
either way it sounds like the flap inside the heater is stuck in the hot air position and or the linkage from the control lever to the flap is not connected. it should be pretty simple and inexpensive to fix.

[WorkinLonghorn]

Also,(and I realize this is kinda lame), on my trucks there always seems to be heat leaking through somehow so I either put a valve on the heater hose or just loop the hose back,bypassing the heater entirely.That way there in ZERO heat coming into the cab.
Temperature today where I'm going; 107 degrees in Woodland Hills Ca.

Next project;AC!

[ChevLoRay]

Go to an auto parts store (I got one from NAPA) and ask for a shut-off valve for your heater system. It won't be factory, but it will fit into the heater hose that supplies your core. Screw down the valve and the water is shut off, and heat is, too.

It's what I did when my heater control valve (in the same hose) began to leak. It's vacuum controlled, so take a look under the hood, on the passenger inner fender....if it is there, you'll see it. It may have gone bad and been by-passed, too.

[Longhorn Man]

count me in for a shut off valve too.

[70C10Toejam]

I had one of the shutoff valves from the parts store. Not so good. Only time it didn't leak was when fully opened, fully closed or when no coolant was present. Was a piece of junk.

I now have 2 ballvalves on it. The upper one is a regular 3/4 in. with hose barbs and the lower one is a 3/4 inch PEX valve, and is just the right size. Might think 2 is overkill, but 2 weeks after putting in the second one, the heater core did a sieve impression when I was at Menards. Shut both and away I went.

Did end up having the old valve, thats the second pic.

[ChevLoRay]

Good call. Any screw-type valve, as the lower one depicts, will leak if the valve is not seated all the way one way or the other. Still, ain't no guarantee that they won't leak if they are. It's a common problem. Ball valve is the way to go, but you don't really need but one to prevent the flow, still having one in each hose will stop the heat transfer a little bit better, than will just one of them.

Ball valves are our friends.

[72rookie]

First off thaks for all the help. After looking into this weekend I noticed that I have no shut off valve at all. Apparently somebody didn't see the need for it and treplaced it with a simple heater hose. Know I can manually turn it off thanks to yalls suggestions.

[jhow66]

To cure problem without the valve you need to clean out the heater box so the air door will close. It is blocked will leaves and such so that it will not close and shut off the airflow thru heater core. Either way will work tho.

[PICKMUP]

AC trucks had a vac actuated shutoff valve...others did not.

[jondancer]

So if I wanted to install a valve, does it go on the inlet hose or out let hose ? Or doesn't it matter?
Thanks

[Custom/Ten]

Originally Posted by jhow66

To cure problem without the valve you need to clean out the heater box so the air door will close. It is blocked will leaves and such so that it will not close and shut off the airflow thru heater core. Either way will work tho.

This was my problem

[KEL]

!!

[slikside]

Yup, this came from waaaaaaaaaaay back!

But to answer the last question, put the valve on the inlet to the heater core, that way it never gets hot. Should be the hose from the water pump.

[jondancer]

Thanks .
Man you guys ***** if we start a new thread and don't use the "search" option . Then if we do use the search option and find what we're looking for but bring up an old thread with good info , everyone makes a big deal if it. Can't win around here .

[KEL]

I was just kidding around.
Don't take offense.
I got caught offguard when I saw Andy's vehicle in one of the responses !

[Custom/Ten]

Originally Posted by jondancer

Thanks .
Man you guys ***** if we start a new thread and don't use the "search" option . Then if we do use the search option and find what we're looking for but bring up an old thread with good info , everyone makes a big deal if it. Can't win around here .

I feel ya man but who cares, those complainers are a bunch of beaches, let them waste there breath. Use the forum however you please, you have my written permission! plus that batman stuff was pretty funny, actually made me laugh out loud, a little anyway.

[89AKurt]

~bumpity bump~

I searched and looked at a few threads about this. 3/4" ball valves, two is better, dependent on state?

[mike16]

at least your heater works. mine is filled with leaves and rats nests. kind of exciting every season when you first turn it on.

[Wrenchbender Ret]

The inlet hose comes off the top of the intake manifold on a V-8 & the therm. housing on a 6. It is the 5/8 hose. You need to put the shutoff valve on this hose.

[89AKurt]

I know why people are putting the shutoff valve in-line, much easier than this way! Had to unbolt the a/c compressor mount. I just didn't want the valve bouncing around.



I know it looks like the belt will hit the valve handle, but over an inch clearance.

[Andy4639]

Doesn't matter which hose the valve goes in. Once you shut the valve the water flow is stopped! The heat can't get to the cab if the water flow is stopped.
Remember the heat comes off the cools from hot water. No flow = no heat so put it wherever you want. I have mine right against the fire wall.

[Wrenchbender Ret]

If you put the heater valve in the return line you have pressure from the water pump on the heater core all the time. It can split the seams of the core & any leak will be a gusher . You will never find a factory valve on the return side.

[89AKurt]

Originally Posted by Wrenchbender Ret

If you put the heater valve in the return line you have pressure from the water pump on the heater core all the time. It can split the seams of the core & any leak will be a gusher . You will never find a factory valve on the return side.

Adding another valve to the intake manifold should solve that?

[Andy4639]

Originally Posted by Wrenchbender Ret

If you put the heater valve in the return line you have pressure from the water pump on the heater core all the time. It can split the seams of the core & any leak will be a gusher . You will never find a factory valve on the return side.

Ok then, why doesn't it split in normal use when running also. It has the same amount of pressure on it then.

System pressure is the same no matter what. The water is going to the least amount of resistance in the system.