Heat water valve questions

C Sickness

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My '70 300 has the four port red plastic vacuum operated water valve. I understand that the theory of operation is that it's controlled by vacuum. Varying the amount of vacuum with the slide control changes the valve from closed at "cool" to open at "hot".

When mine is all the way at cool, i still feel warm water in the hoses on the heater core side of the valve. The engine side is hot. I think the valve may be leaking. I would expect the heater side to be cold.

Can the valve be disassembled and "cleaned", or "repaired", or is it just time......?
 
My '70 300 has the four port red plastic vacuum operated water valve. I understand that the theory of operation is that it's controlled by vacuum. Varying the amount of vacuum with the slide control changes the valve from closed at "cool" to open at "hot".

When mine is all the way at cool, i still feel warm water in the hoses on the heater core side of the valve. The engine side is hot. I think the valve may be leaking. I would expect the heater side to be cold.

Can the valve be disassembled and "cleaned", or "repaired", or is it just time......?

Odds are the internal diaphragm is leaking and causing the valve to be stuck in place. If you have access to one of those small hand held vacuum pumps with the gauge on it that is used for checking vacuum advances, you can use that to check the heater control valve. If you do not have one of those, you can use a piece of clean vacuum hose hooked to the primary vacuum port and suck on it lightly to see if it holds vacuum, be careful doing this as if the valve has an internal leak you can suck up antifreeze. If the valve holds vacuum, check the various hoses under the dash that are hooked to the vacuum control running to it for leaks. With ATC there numerous possible places for vacuum leaks that will cause the valve to be nonfunctional. The seat that is supposed to shut off the hot water could also be plugged with sludge or other crud. You can try removing the valve from the car to see if the valve can be flushed out with a garden hose. I do not recommend trying to disassemble the valve.

Dave
 
There are replacements, but they don't look the same.

I replaced mine with a 4 seasons unit (original was long gone anyway) and it works OK, but I added a small valve in the line too so that there is no hot water circulating to warm my cooling breezes. Once I need heat (spring and fall), the valve gets opened and it stays closed the rest of the time.

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I guess i could put the valve on the workbench, and operate it with the Mighty Vac. Maybe try to flow some water through and see if it's leaking. Too bad there is no "kit" to renew the plungers and seats, or whatever is in there.

Mine is just standard A/C, no exotic ATC.

I like John's manual valve. We haven't had winter here in Florida the last few years. I could probably just turn it off and leave it. A/C is my main interest.
 
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See here for a link to two threads and a thorough discussion. The Everco 1949 HCV that I bought last year continues to work well.
 
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