Thermostat housing 2 ports what are they?

[Lorenblazerk5]

Hi new to this site, I am super impressed at the deep knowledge shared Thank you!

Can anyone tell me what this is? How to test or replace. 2 port in thermostat housing left one has an electrical 2 prong sensor and the right has this what look like it attaches to vacuum hoses. Any help would be appreciated.

1985 Chevy K5 Blazer 350 5.7 4x4 original.

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[Ricko1966]

What's pictured looks like the temperature switch for a dual capacity accelerator pump. Does your carbureator have a plastic electrical connector on the passenger side top front corner? You should provide a pic of the thermo vacuum switch in question,preferably in position on the truck.

 

[Lorenblazerk5]

Yes the Carb does have carburetor has a plastic electrical connector. CA truck so every possible smog junk. I will shoot a pic tomorrow Thx.

 

[Turbo4whl]

That is a temperature controlled vacuum switch. In your picture it is missing the plastic hose connection.

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This picture shows a different mounting, best I could find. The vacuum switch is part of the Trapped Vacuum Spark control that your truck had when new. Keeps full distributor vacuum advance when the engine is cold. There would be a second thermal vacuum switch that controlled vacuum to the EGR valve.

 

[Ricko1966]

Yes the Carb does have carburetor has a plastic electrical connector. CA truck so every possible smog junk. I will shoot a pic tomorrow Thx.

CA. Truck may change a lot of things. Does the carbureator have a second electrical connector bottom drivers side front.

 

[Ricko1966]

Why is this the exact same pic from another thread on a different vehicle?

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[Lorenblazerk5]

Thanks for the help here is the pics

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[Lorenblazerk5]

Thank you for the help. pic above

 

[Ricko1966]

Okay so that's a computer controlled quadrajet. CA only on these trucks. Not a dual capacity accelerator pump quadrajet like all the other states. If you can get me a good shot of the vacuum routing sticker I may be able to figure out how to test the thermo vacuum switch. But I do not know what the temperature switch controls or how to test it. If I were in question of whether it worked,I'd unplug the wires and run continuity cold. Then I plug the wires back on get the engine hot,turn it off pull the wires and check continuity again. It most likely is simply an on/off temperature switch. In which case it will read open at.one temperature extreme and it will read zero resistance at the other temperature extreme. When I say hot I don't mean warm. I mean cold and operating temperature.

 

[Radiohead]

Looks like the one I broke the other day doing the fuel line up to the carb. Mine is the egr vs engine temp sensor. I know these things are brittle at this age, but ffs.

 

[Lorenblazerk5]

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[Lorenblazerk5]

The person that painted this truck had some overspray on the sticker hopefully you and see it clear enough.
I will take the resistance readings as stated above. Thank you

 

[Ricko1966]

The person that painted this truck had some overspray on the sticker hopefully you and see it clear enough.
I will take the resistance readings as stated above. Thank you

That one is simple there should be 2 ports on that switch if you put a vacuum hose on 1 port and nothing on the other,you should be able to blow air through the hose and out the open port,when the engine is cold, should not be able to or not as able to when the engine is hot. 1 port goes to a valve at the passenger side exhaust manifold,the other port to carburetor. It closes the valve when the engine is cold to help warm the intake manifold. Looking at that temperature switch. It may just use 1 wire or 1 wire has been pulled out. The way I told I'd check it with an ohm meter? I still would,but would also check continuity between the 1 pin that is being used and the brass base of the switch.It may be a temperature based ground and the base I'd the ground.

 

[Turbo4whl]

Loren, your first picture thew me off. Looking at the vacuum diagram, your truck should only have one TVS, (Temperature Vacuum Switch) mounted in the cooling system. As Rick stated, it operates the heat riser at the exhaust.

Just for clarification, the other TVS mounted on the air cleaner controls the flap valve in the air cleaner. Also looking at the diagram, your truck does not have Trapped Vacuum Spark. What also does not look right, the wire connector on the second temperature switch has room for two wires, only one wire on one side.

Originally you asked about vacuum hoses, do you have hoses not hooked to anything?

 

[WFO]

Thanks for the help here is the pics

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I broke the hose nipple off one of those while changing the thermostat on my 79 Vette.
It looked just like yours. The one I bought looks a little different, but works the same.

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