Thermostat housing issue???

[ellisjay2]

I flushed my cooling system and pulled the thermostat out, but broke a round cap shaped tube that was screwed into the top of thermostat. Only a section broke off, and the rest is still screwed in. It has some kind of valve needle sticking out of the screwed in piece that looks like to me would rise when thermo opened and then coming out of the round piece that broke were two small ports, pointing towards the carb. I've been trying to find this exact fitting to replace or replace the whole thermo, but the only ones I've found dont have the attachment just solid pieces. I looked on lmc trucking and 32-0160 under thermostat looks to be the exact one. The issue im having now is that when the motor has cooled after running, when I open radiator cap, some coolant comes out under pressure, as if the part were some kind of pressure release valve or something????

[Axle]

That part is a thermal vacuum switch. When the coolant gets to a certain temp the valve opens up allowing vacuum to whatever device is further down the line.

Ie:EFE valve in the exhaust, in this case, it allows vacuum to pass until temperature reaches a certain point and then it closes the passage in the switch.

If nothing is currently attached to those ports, you can get a regular thermostat housing without any holes in it.

Alex.


Alex.

[ellisjay2]

No nothing is attached to the ports or was before it broke off, I kind of figured it provided vacuum to something, but what threw me of was the coolant splurging when taking the cap off after the engine is completely cold???? I took alot of vaccum line off since I dont need emissions, do any vaccum lines help with fuel/air mixture for better fuel economy?

[Dead Parrot]

If you can unscrew the broken gizmo, a standard pipe plug, either 1/2 or 3/8 depending, should fit.

You might have some air trapped in the heater core causing the coolant to come out when opened.

As for vacuum lines, my non-emissions 75 has the following:
Distributor vacuum advance to manifold vacuum port on carb (Many threads discuss why)
Thermac system on stock air cleaner housing to manifold vacuum if aftermarket carb or to special port on a Qjet.
Other Thermac lines on the air cleaner housing.
PVC valve to port on carb.
A larger hose from valve cover to air cleaner PVC filter. (Not really a vacuum line but..)

[Desert1957]

JEGS

Chevrolet Performance#809-10108470
Thermostat Housing
Small and Big Block Chevy V8
Cast Aluminum
1/pkg
Fits Applications:
1966-1995CHEVROLET1968-1995GMC
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