View single post by Frank Schwartz
 Posted: 03-31-2014 05:20 am
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Frank Schwartz


Joined: 02-18-2011
Posts: 279
Yes, that is partially correct...however I have seen some early Jensen Healeys that did not have that mysterious little valve at all.... One line from the vacuum goes to the magic plunger switch..the other goes to the water valve, vacuum operated. The valve works like this: with the heater turned off, the vacuum coming into the switch is actually going to the vacuum operated water valve. When the switch is turned off, the vacuum going to the water valve is on...kinda wierd. Bruce Madden in Atlanta told me he had some new old stock of this water valve...

So..when the engine is running there is vacuum to the valve via the magic gimmick and when you shut the engine down you can actually see the valve open as the vacuum is gone. Then when you start it up, the vacuum closes the valve and you get no heat...turn on the heat and the vacuum is released and the valve would think it should be the other way around..but it is not.
Many JHs have this water valve and it is often rusted so bad that it is useless...I should add.