Put coolant in my car today. Fortunately no leaks so far with the exception of my new heater valve. I understand that the original seal may not be available any longer. I used a single "O" ring which I thought would do the job but it obviously has not. I did not use any type of sealant between the mounting face on the heater box and the valve. Perhaps I should have?

I would appreciate any suggestions or tips on how to deal with this issue. Thank you!

Lin

 

There's supposed to be two "O" rings in there of the same size.
And as far as I know, there were always O-Rings on there.
So I'm not sure what you mean by "original seal".

 

There is only 1 "O" ring not 2 Jeff as far as I know, part no C9928.

It is available from SNG, if you have the correct "O" ring and it still leaks, I would assume there is an issue with the casting/machining of the heater valve, I will put a micrometer on the "O" ring and check the dimensions if you like, and I can also check the seat size in the heater valve.

When I assembled mine the valve was a good fit into the "O" ring not tight, but definitely not slack, and then the "O" ring is compressed slightly when the valve is tightened onto the heater box, this should squeeze up the "O" ring and create the seal. If this is too slack going into the "O" ring when assembled it will not seal when compressed, or if the seat in the valve is too deep it won't compress the "O" ring and again no proper seal. If the seat is too deep, you could machine a little off the heater valve flange so the seat is not as deep.

 

Odd why the parts manual only shows one O-ring.
On my car there are two female fittings on either side where the O-ring(s) go.
It's indented (concave taper if you like) in the heater box side as well as the tap side.
My car takes two O-rings to fill the void.
If were to use only one O-ring, it would leak for sure.

 

It does have the 2 concave faces, you are absolutely right, but the "O" ring is pretty fat, probably about 1/8" thick, my car only had one fitted.

As a general rule one would never fit 2 "O" rings in the same point as you can't determine how they will seal against each other when compressed, that's not to say I haven't done it when I haven't got the correct "O" ring t hand !

 

Maybe that's the problem that the OP is having.
The original fat O-ring isn't available any more ???
Even tough SNG lists it, it's probably the wrong one.

When I first bought the car, it had two rings it, but never leaked.
I replaced the tap quite a few years later because the diaphragm inside started leaking and put in two new rings.
Now here I am years later again with a new matrix and it still isn't leaking, so I'm just going to leave it _ even if it isn't correct.

 

Jon,
I ordered a few new "O" rings with the proper part number. I will report back on my experience after installation. Thanks.
Lin

 

Got the proper "O" ring from Terry's Jaguar. Fit like a charm and no more leaking. I can't explain why the one I had was undersized but I am pleased that I now have the proper one in place! Thank you to respondents.
Lin