Heater control valve disassembly

[Arnoldsat]

Dear friends,
10 years ago my heater control valve started leaking coolant. The Newport is from 1971 with manual AC and finding the correct part was not easy and pricey but I bought a NOS one. Last month I needed the heater but the car stayed cold. After much searching I found two problems: the heater control valve did not get all the vacuum.
The Service Bible said 14 in/Hg but it got about 9. Sorry about the rainy picture.

The lever in the dashboard was a bit wonky and after some tinkering I got it to put 14 to the heater control valve.
Still the car would not get warm. I replaced the thermostat just to be sure but that did not help.
To test the heater under the dashboard and internal vacuum doors I bypassed the heater control valve altogether

This brought desert temperatures in the car, I almost burnt my leg. So that part was working. That led me to the second problem.
With the vacuum pump I found out that the second heater control valve was leaking vacuum. I could pump but it would not hold vacuum.
So one heater control valve leaked coolant, and one leaked vacuum air.
I figured I could try to make one good one of the two broken ones. They go about 150 dollars on evilbay and with shipping and taxes I would be set back well over 200 dollars so I should try at least.

I bent a piece of thread years ago with a metal bar on top to keep the pressure of the top and bottom together.
Top middle and bottom were 'glued' together with liquid gasket. Also called that RTV sealant I think?

The first attempt was okay for heating, the Newport was comfy again. But coolant started leaking from the weep hole.
I was ready to cease my efforts but I gave it one more try.
Disassembly revealed that somewhere in the top, the weep hole was air connected to one of the screw holes.
I plugged that screw hole, the weep hole needs to stay because of the vacuum operation. Can't plug that.
My bent piece of thread with a metal bar on top were handy, I could do without the screws altogether if I wanted.
The screws are probably the main reason the plastic (Bakelite?) starts cracking because that's where the cracks are.

So this is it. The heater works as it should now, and the heater control valve does not leak anymore.
The main reason for this post is to show my MOPAR friends that there is some stuff you can try yourself with those pesky heater control valves, although it's not much.
Arnold.

 

[saforwardlook]

This topic has been discussed in detail in this previous link:

Heater Control Valve Idea

 

[Arnoldsat]

I'm aware of that thread, but nobody talked about disassembling the HCV.

 

[ImperialLeBaron1969]

Dear friends,
10 years ago my heater control valve started leaking coolant. The Newport is from 1971 with manual AC and finding the correct part was not easy and pricey but I bought a NOS one. Last month I needed the heater but the car stayed cold. After much searching I found two problems: the heater control valve did not get all the vacuum.
The Service Bible said 14 in/Hg but it got about 9. Sorry about the rainy picture.
View attachment 627080
The lever in the dashboard was a bit wonky and after some tinkering I got it to put 14 to the heater control valve.
Still the car would not get warm. I replaced the thermostat just to be sure but that did not help.
To test the heater under the dashboard and internal vacuum doors I bypassed the heater control valve altogether
View attachment 627081
This brought desert temperatures in the car, I almost burnt my leg. So that part was working. That led me to the second problem.
With the vacuum pump I found out that the second heater control valve was leaking vacuum. I could pump but it would not hold vacuum.
So one heater control valve leaked coolant, and one leaked vacuum air.
I figured I could try to make one good one of the two broken ones. They go about 150 dollars on evilbay and with shipping and taxes I would be set back well over 200 dollars so I should try at least.
View attachment 627082
View attachment 627085
View attachment 627086
I bent a piece of thread years ago with a metal bar on top to keep the pressure of the top and bottom together.
Top middle and bottom were 'glued' together with liquid gasket. Also called that RTV sealant I think?
View attachment 627094
The first attempt was okay for heating, the Newport was comfy again. But coolant started leaking from the weep hole.
I was ready to cease my efforts but I gave it one more try.
Disassembly revealed that somewhere in the top, the weep hole was air connected to one of the screw holes.
I plugged that screw hole, the weep hole needs to stay because of the vacuum operation. Can't plug that.
My bent piece of thread with a metal bar on top were handy, I could do without the screws altogether if I wanted.
The screws are probably the main reason the plastic (Bakelite?) starts cracking because that's where the cracks are.
View attachment 627105
So this is it. The heater works as it should now, and the heater control valve does not leak anymore.
The main reason for this post is to show my MOPAR friends that there is some stuff you can try yourself with those pesky heater control valves, although it's not much.
Arnold.

fantstic! I love posts like this.

 

[3175375]

Good work!

Your efforts are good to know.
I did some similar disassembly/repair/assembly with limited success on a vacuum controlled heater actuator for my 1969 Plymouth Fury III vert.
I still have the bad actuators (3 I believe) and will revisit repairing them in the future.

You are correct using RTV as a description for the silicone sealant.

Just a note for you: A fancier method to clamp the two halves of the heater valve, maybe be more effective and less damaging to the case.

 

[GOLDMYN]

I have a question, On many pix of 1971 Newport I see 2 different types of HCV anyone have comment? My car is 1971 Newport w/ac

 

[Arnoldsat]

What a beautiful Newport! Love the color & fender skirts

Your heater control valve pictures look like this EVERCO H1949

Here is where I found the picture: NORS Mopar Heater Control Valve 1969-71 B & C Body W/ A/C - Hiltop Auto Parts

Cheers

 

[GOLDMYN]

Thank-you, mine works. just wondering if there was always (2) different style, was one better?

 

[saforwardlook]

What a beautiful Newport! Love the color & fender skirts

Your heater control valve pictures look like this EVERCO H1949
View attachment 627331
Here is where I found the picture: NORS Mopar Heater Control Valve 1969-71 B & C Body W/ A/C - Hiltop Auto Parts

Cheers

I fail to understand why anyone would put fender skirts on those models - the rear end ride height was borderline without them but with them it just looks like the car is overloaded in the trunk and is constipated, having difficulty taking a dump..........

 

[Big_John]

Thank-you, mine works. just wondering if there was always (2) different style, was one better?

From everything I've read and seen personally, the original heater valve was junk and would often fail within a couple years. The "fix" was the replacement Everco (or similar brand) valve which functions exactly the same as the original, but lasts much longer. In fact, I can't even remember seeing a car being driven regularly that still has the original heater valve.

Somewhere, in the dusty corners of my brain, I seem to remember something about even Chrysler dealers using the Everco valve as the warranty replacement, but that might be completely wrong. It would be worth looking at service bulletins from those years. I do think that a lot of the dealers did use these as replacements for non-warranty work.

 

[Big_John]

I fail to understand why anyone would put fender skirts on those models - the rear end ride height was borderline without them but with them it just looks like the car is overloaded in the trunk and is constipated, having difficulty taking a dump..........

I dunno... I kind of like them.

 

[saforwardlook]

fantstic! I love posts like this.

I also took apart one of the factory heater control valves an sent the unit to a friend of mine here in California that also makes/fabricates the Autotemp II control units to see if he could also fabricate a replacement out of aluminum for the standard heater valve and he told me it would not be feasible at any reasonable price. I was actually very surprised at how complex it was inside and I wonder how Ranco (I think the original supplier for that part) was able to even design and fabricate the part. That part should have never been made of bakelite plastic that cracks so easily.

 

[3175375]

I also took apart one of the factory heater control valves an sent the unit to a friend of mine here in California that also makes/fabricates the Autotemp II control units to see if he could also fabricate a replacement out of aluminum for the standard heater valve and he told me it would not be feasible at any reasonable price. I was actually very surprised at how complex it was inside and I wonder how Ranco (I think the original supplier for that part) was able to even design and fabricate the part. That part should have never been made of bakelite plastic that cracks so easily.

I’m surprised that your contact said it’s too hard to make. With 6 axis milling machines, wow.

 

[Big_John]

I also took apart one of the factory heater control valves an sent the unit to a friend of mine here in California that also makes/fabricates the Autotemp II control units to see if he could also fabricate a replacement out of aluminum for the standard heater valve and he told me it would not be feasible at any reasonable price. I was actually very surprised at how complex it was inside and I wonder how Ranco (I think the original supplier for that part) was able to even design and fabricate the part. That part should have never been made of bakelite plastic that cracks so easily.

I’m surprised that your contact said it’s too hard to make. With 6 axis milling machines, wow.

The bakelite body would have been cast with minimal, if any secondary machine work.

The mold might have been a little complicated to build, but you would be really surprised what a good moldmaker can do. I've never seen the inside of one, so I can't make too much of a guess and honestly, my casting experience is pretty limited.

Probably the way to do it is to cut one up and figure out how to investment cast the part if you really want to duplicate it.

If it were me, I'd look at making the exterior to camouflage an existing valve that works... But that's just an idea.

 

[Just Carbs]

I fail to understand why anyone would put fender skirts on those models - the rear end ride height was borderline without them but with them it just looks like the car is overloaded in the trunk and is constipated, having difficulty taking a dump..........

It's for MPG.

 

[saforwardlook]

It's for MPG.

If you are driving one of these cars in the first place, you obviously do not have mpg as a serious concern. I would easily give up mpg to avoid the ugliness of such a styling turn off. The rest of the styling on those models was just excellent. The styling of the flat faced/straight up front ends of the formals really hurt mpg by comparison. Probably one of the best styled vehicles ever were the 1966/7 Buick Rivieras and whose large wheel openings were well worth any claimed mpg by covering them up.......................

I do not find myself thinking that a stray dog taking a dump on my front lawn is a beautiful sight.....................

 

[saforwardlook]

There are different valves for regular AC and Autotemp AC

Why are you making this point? In either case, both were subject to cracking after about 2 years of normal use due to the use of bakelite plastic housings.

 

[Arnoldsat]

I've never seen the inside of one, so I can't make too much of a guess and honestly, my casting experience is pretty limited.

That was a good reason for me to take more photographs

Top↓ You can see clearly the cracks are on the outside of the screw holes

Top with rubber seal in place↓

Middle↓

Middle↓

Filthy but with the valve in place ↓

With rubber seal↓. The black circular plastic in the center (with gap) is the actual heater control valve,
The rubber valve with 19 stamped on it is for warm coolant to return to the engine if the heater is off or low.
There is always coolant flowing, whether the car is being heated or not.
That is a fundamental difference to the replacements I've seen. When they are off, no coolant flows back to the engine.

Bottom↓

The top (with the vacuum diaphragm) I can't take apart without destroying it.
Maybe I will because it's leaking anyway.
Cheers Arnold.

 

[Big_John]

That was a good reason for me to take more photographs

Top↓ You can see clearly the cracks are on the outside of the screw holes
View attachment 628105
Top with rubber seal in place↓
View attachment 628106
Middle↓
View attachment 628107
View attachment 628108
Middle↓
View attachment 628109
View attachment 628110
Filthy but with the valve in place ↓
View attachment 628111
With rubber seal↓. The black circular plastic in the center (with gap) is the actual heater control valve,
The rubber valve with 19 stamped on it is for warm coolant to return to the engine if the heater is off or low.
There is always coolant flowing, whether the car is being heated or not.
That is a fundamental difference to the replacements I've seen. When they are off, no coolant flows back to the engine.
View attachment 628114

Bottom↓
View attachment 628115

View attachment 628113

The top (with the vacuum diaphragm) I can't take apart without destroying it.
Maybe I will because it's leaking anyway.
Cheers Arnold.

While it looks a little complicated, I could see that it's molded and possibly a little secondary machine work for the mating faces. I've been in mold making shops where more complicated parts were being made, and knew a few of those guys years ago. To tool up for this one would be expen$ive and amortizing that cost would be tough, so I don't see that happening.

That is a fundamental difference to the replacements I've seen. When they are off, no coolant flows back to the engine.

I didn't know that... Interesting.

You can see clearly the cracks are on the outside of the screw holes

If careful, a little epoxy in the right places and Heli-Coil inserts could repair that pretty easily.

 

[glennb49]

I think the skirts look great on your Newport, Especially being a coupe with those long quarters! They look the same as what came standard on 72-73 Imperials!