Will someone explain the operation of a 1970 heater control valve?

[XH29N0G]

My heat is stuck on.  I do not know if it is related to the adjustment of the cable (inside) or the vacuum pot on the outside of the heater control valve.  The FSM states that the vacuum pot is for a water shut off.  I think that is what I want to control. 

The vacuum hoses have been removed, so there is no hose on that vacuum pot.  If I connect a hose, will it shut off the hot water to the heater core?

[Ghoste]

It needs vacuum to operate.

[Ghoste]

Meaning yes, hook it back up.  I don't know it'll solve your problem but its hard to diagnose with only a partial system operating.

[hawkeye]

Unless you have had your valve rebuilt, there is a good chance it will not seat properly even with vacuum.  Best to plumb a shut off valve in your heater hose.

[Ghoste]

That would be kind of a hassle for when you do want heat though, no?

[hawkeye]

Most people only drive their cars in the warm weather.  I guess I would rather have to open the hood to turn the heat on than have the heater blasting out hot air all summer.

[Ghoste]

Fair enough.  I use mine in the cool but not snowing seasons too and the odd summer emergency where I flip the heat on for a little help to the radiator so I was thinking about those things.

[Dino]

The little plastic shut off valve in the copper tube is likely worn.  You can order a new one on ebay.  Your problem is that you cannot shut off the water flow, same thing happened in my 69 in the middle of August.  Damn that was fun!   

The cable also controls the amount of movement the plunger makes so check the cable first.  Maybe all you need to do is tighten it although it's still a good idea to replace the plunger head and the rubber seal that prevents water running on your carpet.

[Ghoste]

Would it be safe to say that some heater core issues are misdiagnosed and repairing this would be cheaper?  (I'm thinking of the leak part here not the heat on all the time portion)

[XH29N0G]

The little plastic shut off valve in the copper tube is likely worn.  You can order a new one on ebay.  Your problem is that you cannot shut off the water flow, same thing happened in my 69 in the middle of August.  Damn that was fun!   

The cable also controls the amount of movement the plunger makes so check the cable first.  Maybe all you need to do is tighten it although it's still a good idea to replace the plunger head and the rubber seal that prevents water running on your carpet.

I have several additional questions that I do not seem to be able to sort out from what I can find in the FSM: 

        Will you point me to what 'little plastic shut off valve' I should order?
         Is the valve removed by loosening the bolts that hold it, and pulling it into the engine bay?
         Is there anywhere I can find a diagram of the internal workings of the valve itself?

Thanks.

[Dino]

The little plastic shut off valve in the copper tube is likely worn.  You can order a new one on ebay.  Your problem is that you cannot shut off the water flow, same thing happened in my 69 in the middle of August.  Damn that was fun!   

The cable also controls the amount of movement the plunger makes so check the cable first.  Maybe all you need to do is tighten it although it's still a good idea to replace the plunger head and the rubber seal that prevents water running on your carpet.

I have several additional questions that I do not seem to be able to sort out from what I can find in the FSM: 

        Will you point me to what 'little plastic shut off valve' I should order?
         Is the valve removed by loosening the bolts that hold it, and pulling it into the engine bay?
         Is there anywhere I can find a diagram of the internal workings of the valve itself?

Thanks.

This is the seal (larger item) and plastic plunger.  The former keeps water out of the cabin, the latter shuts off the water flow, ie shuts off the heater.
http://www.ebay.com/itm/DMT-68-69-B-Body-AC-A-C-RANCO-Heater-Water-Control-Valve-Repair-Kit-Seal-/291001034925?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3ADodge%7CModel%3ACharger&hash=item43c10368ad&vxp=mtr

Remove the three screws holding the valve to the firewall and pull it out.  Undo the retainer holding the temp cable to remove it completely.

Same brand valve with same method of operation:
http://www.packardinfo.com/xoops/html/downloads/HOW-TO%20Ranco%20Valve%20Seal%20Replacement.pdf

Also do a search for heater or water valve to find a few posts, some by me.

[Ghoste]

Is there an easy way to tell if its failing or are you pretty much looking at yanking it and dismantling to know?  ( a lot of questions I know but there is a slight coolant smell inside my car without evidence of a core failure- wet carpet etc.)

[hawkeye]

The 70's are different (don't ask how I know).   If your plunger is good, all you need to rebuild a 70 valve is a couple of O-rings.  If your plunger is bad you might have to have it professionally rebuilt.  I don't know of anyone who sells the plungers.  Call  http://www.classicautoair.com/  or http://www.heatercontrolvalve.com/index.html.  You can tell if the plunger is bad by shutting the heat off and disconnecting the heater hoses.  If you can blow though it  the plunger is bad.  If it is leaking the O-rings are bad.

[Dino]

The 70's are different (don't ask how I know).   If your plunger is good, all you need to rebuild a 70 valve is a couple of O-rings.  If your plunger is bad you might have to have it professionally rebuilt.  I don't know of anyone who sells the plungers.  Call  http://www.classicautoair.com/  or http://www.heatercontrolvalve.com/index.html.  You can tell if the plunger is bad by shutting the heat off and disconnecting the heater hoses.  If you can blow though it  the plunger is bad.  If it is leaking the O-rings are bad.

One quick note on that.  My plunger turned out to be just fine.  The copper tube however was no longer 'round' to make the seal so a good fitting wooden dowel and a small hammer fixed that issue.

Is there an easy way to tell if its failing or are you pretty much looking at yanking it and dismantling to know?  ( a lot of questions I know but there is a slight coolant smell inside my car without evidence of a core failure- wet carpet etc.)

If the firewall seal is busted you should find a trace on the firewall (check both sides).  The smell can also originate in the heater box itself though.  In these cases I would rebuilt the whole thing.

[Ghoste]

No matter what though, if there is even a slight smell of it inside the car, there is a leak in that heater someplace.

[Dino]

No matter what though, if there is even a slight smell of it inside the car, there is a leak in that heater someplace.

I think that is a reasonable assessment yes.

[Ghoste]

Thats okay, make a nice winter project. 

[Dino]

Thats okay, make a nice winter project. 

Are you thinking 'I should've bought that heater box rebuilt kit at the swap meet?  Because that's what I thought two years ago.      I was happy to find out the heater still works as it should though so no need just yet but it's only a matter of time.

Did you go to the meet btw?

[XH29N0G]

Thanks for the information.