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940 heater valve

J

jambo

Member
Joined
May 15, 2005
The 940 has become the rarely used, second car (the first being a 240 wagon). Of course I still love it, even with peeling paint. A drip is showing from the lower heater hose, can't trace it yet, but it may be around the heater valve. For sure I don't want to spend a hundred plus for a valve. Even the cheaper Motorcraft one makes no sense if all it affects is the A/C I never use. Can I really just bypass it, and that's that?
 
Sure, you can bypass it but then you'd have hot water flowing continuously through the heater core.

I've had two heater control valves fail on our 940, each of them had the plastic portion rot out and fail.

I recently replaced one with a Motorcraft YG136 Heater Valve .

31YDPSR5H4L.jpg
 
The super cheap route is to replace it with a manual valve from the hardware store, open it in winter and close it in summer.
 
I bypassed mine and do not see any difference in temp control function. I think the valve is only completely closed on Max AC setting and that drops just couple of degrees F.
 
It should be closed on AC and with the temp control at full cold. Makes a big difference on mine if it is stuck open during the summer, around 10-15* at the vents when cruising.
 
fix for now

The inside diameter of the inlet hose is 5/8ths" so I put a piece of half-inch copper pipe at 5 and an eighth inches (an inch and a half for the removed valve, and the rest, the longest it could be without encroaching on the bends in the rubber), which seems to work out well, rounding the outside of the copper at the edge so it won't cut the rubber. Then, all happy-----then not-- after a few minutes of running it noticed a pinhole leak in the hose. This was probably the whole problem with leaking all along, and it never was the valve or the hose at the valve. So I ordered a fresh hose and while waiting for it used a hair dryer, super glue, duct tape and a hose clamp to repair the leak. A couple of hundred miles on, some of them highway, the reservoir is staying steady. My mechanic says the hose installation is not a cakewalk for a garage hack, and good luck with it. In the meantime, I do not miss the valve in nearly ninety degree Connecticut weather, driving with a couple of windows cracked, no A/C. I'm not even sure about re-installing the valve when I get around to changing the hose. The way I read it above in gsellstr's link @ "Some good info in here as well...
http://forums.turbobricks.com/showthread.php?t=246617," sending coolant through the heater core at all times means there is more "coolant flow around the backside of the head." This, to me, sounds like a good thing, so why really have a shut-off valve in the absence of A/C and if a little extra heat at the firewall is not a personal issue? I doubt this car will ever see California, though my brother's out in Guerneville . . . guess I'll keep the valve, just in case.
 
Just be careful working around the heater core, you don?t want to have to change that. You?ll need it in Connecticut winters.
 
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