Leaking heat control valve

[Steve Meltzer]

The heater control valve (near the firewall) on my GTC is leaking (it's always something with these cars). I removed the four little bolts and pulled the cable controlled top off the reservoir and replaced the old, corroded rubber seal with a new one, but it still leaked. So, I thoroughly cleaned all of the surfaces, and used black silicone on the seal...no better, still leaks. Maybe I need to remove or at least loosen, the control cable so that it's not putting any undue stress on the repair, but am I missing something here?
I installed it with the "bubble" up (convexity up). Is it in back asswards? Sad day for the list, when 20% or more of the posts are mine! thanx into perpetuity for your patience. steve

[Steve Meltzer]

OH yeah, it's leaking coolant from the center of the valve, where the cable operates, not from the sides nor bolt holes. steve

[Jim Wickstead]

Steve,
Had the same problem with mine. Replacement diaphrams are readily available and easy to install. Partsource carries them among others. Not expensive. I think this will fix the problem. Need to be careful of the two hose connections on the housing. They tend to corrode and are easily broken. New castings are hard and costly to come by.

Jim W.

[Steve Meltzer]

Jim, thanx for the info. I don't think i did a good job of explaining my problem. The diaphragm is new. (I called it a seal.) Where did I go wrong? s

[John Vardanian]

Hi Steve, I presume the leak is coming from the operating shaft. Here's the thing, the valve is made up of two chamber, lower and upper. The lower chamber is always wet, while the upper one is always dry. If you are getting water in the upper chamber that means you diaphragm is no good. I'd suggest removing the new rubber you just put in and checking it again for holes.

john

[Steve Meltzer]

oooh, oooh you mean it may not be my fault???! I'm fixin' (this is correct English in Texas) to adjust the valves and while I have the carb linkage return spring out of the way, I'll pull it once again. thanx. s

[tyang]

Hi Steve,

This is going to sound stupid, but i have to make sure the seal is oriented correctly. The seal should be stretched over the plate the moves up and down when the cable is operated. I can't imagine you would have installed the seal upside down, but I'm just making sure.

Tom

[tyang]

Although this picture is not great showing it, but the seal at the bottom of this picture has a space that slides over the disk the arrow is pointing to.

Tom

[Steve Meltzer]

thanx for the picture, Tom. I think I had it right, but when I pull it to check the diaphragm, i'll be more certain. did you use any black silicon? thanx again. s

[tyang]

I only put a little silicone on the edges.

Tom

[Yale]

Wouldn't it be great if someone remade this ridiculous thing in a way that looked the same BUT worked!

[Steve Meltzer]

Just before I left town this AM, I took the top (the part to which the operating cable attaches) off the coolant res. I think my "new" diaphragm may have a hole in it, but maybe only heated pressure conditions. At any rate, I'm also not sure the guts of mine look like Tom's picture as there's no loose disc on the inside. I'll revisit this when I return from vacation and perhaps post pictures at that time. thanx again. steve

[Steve Meltzer]

Just back from a short vacation and looked carefully, again, at the control valve. There's no disc, like Tom's arrow shows. I can't imagine that I lost it, and suspect it was never there in the first place. Since I live in Houston, I've never touched the heater in the 8+ years of my stewardship. I'm sure I'd need it to make the heater work, but it doesn't look like it's required to seal the unit, as I suspect it was sealed before it began leaking. Is this correct or should I start looking for the disc or ??. thanx again. steve

[DWR46]

Steve: I have never seen a separate disc in a heater valve. I noticed it in Tom's photo and do not know what it is for.

[tyang]

The picture is misleading because it was meant to illustrate a post I had written a while ago. The valve has a disc riveted to the shaft that is operated by the control cable. As the cable is pulled, the shaft moves up and down opening and closing the valve. The disc sits inside the rubber valve so when the shaft moves up, it pulls the valve open.

Tom