In the summer I had bypassed the heater valve in my '85 XJ6- bad enough no cooling, but heat always on was worse.

Now I'm ready to reconnect it and am debating whether to get a new one or use the original.

It doesn't leak coolant, it holds vacuum, and when I apply vacuum the plunger retracts and the valve part turns, at least as far as I can see from the outside.

Does this mean it's fine, or can that valve turn and yet still allow hot water to flow through the valve?

Thanks,

-mB

 

as long as the diaphragm inside is not torn, it should be good.

 

Not common, but everything can be operational on the outside but the actual gate on inside is broken off from the external actuating mechanism

You could remove the valve and operate the lever arm while looking inside the valve. Do you see the gate open and close?

Cheers
DD