I need to replace the temp sensor on my 71 GS 350. I tested the gauge (grounded the wire) and it works. I was looking at replacement sensors, and some look like the one that's on the vehicle, but they say they are the " for light" sensor. I have a temp gauge, looking at those sensors they look different from what I have. The gauge sensors look similar to the unknown part in the picture. What is the correct sensor I need, and what is that part on the other side of the manifold? All help is appreciated.
I might be mistaken but i believe the thing you have squared off in red on the right side of your picture is the bottom part of what used to be a tree looking vacuum tube assembly. From what i have seen they screw in on that side and direct the vacuum to the distributor to help up the idle when the car was cold and then close off when the car got warmer. Or it could be as simple as a after market secondary temp sensor?? Pull it out and see what it looks like. Im sure a better more correct answer will be posted by an a more experienced member. I am still learning the Buick engines.
This site never fails to teach me. I read that the thermostatic vacuum switch is an emissions part, I guess it's not necessary anymore? Does anyone know the correct temp sensor part number?
The part you have marked with ????? marks is the Thermo vacuum switch . Its purpose was to send full vacuum to the distributor when the coolant temp hit I think 215 -225 degrees. the idea was it would speed up the engine RPM's to help cool the engine . The temp sensor is the temp sensor. The thing you have marked as the temp sensor wire is NOT. Its a little hard to see but if it has 2 wires it is for the TCS Transmission control Sensor . The definition of it has been posted many times on here by Larry the Wizzard . Short to say it didn't allow distribution until the vehicle was in 3rd gear The Shop Manual describes these item in great detail . Well worth the purchase price of a shop manual
But I grounded that wire and the temp gauge went from C to H. It was also connected to the sensor, I just removed it to test it.
BTW, the temp sensor wire is the green wire. I'am still not sure what the connector with the two pink wires are for, I was thinking that's for the AC compressor that's no longer there.
Can't really see it good in the picture but the green wire is the temp sender. The 2 pink wires is the TCS
The TCS is the same in 1972. This is the page from the 1972 Chassis Manual. The TCS emissions system was a performance and gas mileage killer. If you want your engine to run worse and get less gas mileage, by all means, replace the thermovacuum switch (if you can find one), and hook up the TCS.
The stock gauge sensor is available from Lectric Ltd. https://www.lectriclimited.com/electrical-devices-components
Two pinks are for the TCS, Transmission Controlled Solenoid. Transmission gets into 3rd gear it would close an internal contact & provide 12V to the solenoid. Solenoid would then open & allow full vacuum to the distributor at highway speeds. Resistor across the two pinks was for radio interference suppression. Midway through '71 Buick added an extension to the pink harness & an idle solenoid on the driver side of the carb..
