2.3L ('83-'97) Basic thermostat question

[iPandaBar]

I bought a new thermostat and a new thermostat housing. First time I've had both new in my hands so I placed the thermostat inside it's housing and blew through it...
Yes I'm sure the thermostat was in correctly.
Air passed straight around the thermostat.
Then I blew directly through the thermostat by itself, the flow was more restricted but still easy to blow through.
Then I thought, maybe it needs to have that clamping pressure of being bolted in to be airtight.
So I installed it and rigged up a hose and I could still blow right through it.
So now the question...
Did I get a faulty thermostat? Or are thermostats not airtight and merely restrict flow so it mostly goes the other way?
I took it back off and I'm kind of scared to install it now!

 

[Josh B]

That's not something I've heard before sir. The only way I've ever known to test a thermostat was to drop it in some boiling water and see if it opens.
Some have an air relief valve that allows it to pass through even if it's closed, maybe that's directional

 

[91stranger]

Does it have a jiggle valve on the t-stat?

 

[Curious Hound]

You, sir, may be the very first person in history to test a thermostat that way. We have no baseline data for comparison.

I would venture to guess that it doesn't have to be perfectly airtight to function, especially considering that there is often a bypass hole there anyway, as others have mentioned.

If in doubt, test it the conventional way in a pot of hot water and a thermometer to see what temperature it opens at.

 

[Uncle Gump]

I wouldn't say a thermostat creates a positive seal... more like a major restriction.

 

[bilbo]

I think the stat has a jiggle valve in it. That would allow air through. When I replaced mine there were issues with how the aftermarket housing was cast, so there ended up being a large bypass where coolant (or air in this case?) was able to run around it and the truck would never warm up. Could you try it with the factory housing?