Temperature gauge sending unit question

[Jeff Berk]

I just got my 260z back from the shop* just in time for winter storage and have a new issue to address. On the drive home, my temperature gauge showed +250 after a few miles. The engine was not hot so the mechanic suggested I install a new temperature sensor. Unless I pulled the wrong part off my car, something does not match up (see photograph).

Just above the old and new sensors is the port it screws into. 

Do I just need to purchase a new retaining nut (https://www.thezstore.com/page/TZS/PROD/SCC13/16-7115) and switch out the blade connector to a female bullet on my wire?

*Welded and reground failed camshaft, installed extra-thick exhaust manifold gasket due to a warped header mating surface. 

Edited November 30, 2021 by Jeff Berk

[SteveJ]

I'm not sure what that thing is on the right because it's not a temperature sender. I usually just order the ones with the integrated threads myself. https://www.rockauto.com/en/moreinfo.php?pk=935425&cc=1209181&pt=4748&jsn=1308

At first I thought that might be the temperature switch, but it doesn't look like what MSA lists: https://www.thezstore.com/page/TZS/PROD/11-3122

By the way, the temperature sender should have a bullet connector like the one on the left (and the one I linked).

The ports for the temperature sender and temperature switch are on the front of the housing below the radiator hose.

The port on the side of the housing should be for the coolant tube for the carburetors.

 

 

[SteveJ]

One more thing, the temperature sender should connect to a yellow wire in an unmolested wiring harness.

[zKars]

The “thing” on the left looks to me to be an aftermarket temperature switch, the kind of thing you use to trigger an electric fan on the rad.  When the temp gets to the right temp that spade terminal is connected to ground, which you use to trigger a relay to turn on the fan.  The 1/4 spade connector is the type of thing I’d expect to find on an aftermarket switch of that type. 

 

[Zed Head]

What is the oil pressure doing?  I think that they use the same internal voltage regulator.  Might be a bad gauge.

Measure resistance of both of those and it might tell you something.  I'm not sure if the resistance curve is the same as a 280Z water temperature sensor but it might be.  Put your probe on the body of the unit and the terminal to measure resistance.

[Jeff Berk]

OK, found the right one to unscrew. It was next to the one I unscrewed first.