Heater control valve

[Sixt8Chrgr]

I tested the above with air, and it appears that when the valve is closed there is a little air getting by. So if a little air is getting by then hot water will get by. Is this normal? Or should it seal off 100%?

Thanks guys!

[Gold Rush]

I believe there is a small bypass port that does allow water to circulated but not through the heater core.  What I saw is more like a small bypass from input back to output connections.

[Sixt8Chrgr]

I believe there is a small bypass port that does allow water to circulated but not through the heater core.  What I saw is more like a small bypass from input back to output connections.

Thanks Gold Rush

[Dino]

It has to seal 100% or you won't be able to turn the heater off. Mine leaked as well. I got a new seal kit and bent the operating arm a bit so that the plunger would retract just a smidge more. Works like a charm now.

[john108]

Air (gas) can get through places where water (liquid) can't.
Depending on the size and configuration of the leak path.