Intermittent Temperature Gauge

[ddezso]

Any ideas why my temp gauge would work about 1 out of every 3 times I drive the car? I certainly get it up to a temperature that would cause it to move, and one out of every 3 times it works perfectly.

I dont think the needle in the gauge is physically stuck. What engine part sends the info to the gauge and where is it physically located? Is there any way to test it?

Oh, I have a 1970Z that has a 1974 260Z engine.

Thanks.........

[=Enigma=]

Check the connection at the sender. Mine is located on the thermostat housing at the front of the head where the upper radiator hose attaches. You will have either 1 or 2 wires coming out of it depending on the year and what smog equip is till on there. The wire that attaches to it heads off towards the left side of the engine compartment by the coil. Clean ot and make sure you have a good connection. If that doesn't work, you may have to dig deeper but start with the easy stuff.

[gator]

most likely the temp sensor. I just changed mine and it had the same prob as yours and it is now fixed. Pretty easy fix really. now .. all my guages work but my oil pressure reads low ..

Good luck with it ...B

[ddezso]

Thanks fellas.

A couple more questions (please refer to attached picture).

Is the device inside the red circle the temp sensor you mentioned? I pulled off the connector and cleaned everything out. It was a bit dirty so we will see. Would a replacement be available at any auto parts store? I didnt see any online.....

Also - there is another thing coming off the thermostat area circled in green. It has 2 wires coming off it that aren't connected to anything. Any ideas what that is?

Again, the car is a 1970 with a 1974 260Z engine. I'm not sure what parts of the engine are from the 70 and which are from the 74.

Thanks...

[280~Master]

Looking at your picture you need to replace the one in the red circle. What I would do is when the temp gauge is working go and pull the red wire if you temp gauge stops working you know which one to replace. They are very easy to replace and don't cost that much. Will interchange with many different years. Take it with you to the parts store and try your year. If they don't have it go up in years and see if they have one for say 76. Just make sure it has the same threads and is the same size.

Good luck

[gator]

yep .. order a new one from the Nissan dealer. they are easy to get. When you take this ole one out ..I would be spraying some penatant on it now .. the nut you see is like a sleeve the fits over the temp sensor and it needs to be twisted, cut, pushed, tapped, drilled ... off the nut very carefully so you dont damage the nut. The clean it up well and slip it over the new temp sensor (it will be easier overthe new one that off the old one). Install it and you will be all set. BTW I also ordered and 83 degree thermostat from Nissan so my car will run a bit cooler than the regular 90 ish thermostat you can find.good to do this at the same time.

Cheers ..Bruce

[zhead240]

http://www.classiczcars.com/forums/showthread.php?t=17579&highlight=temp+sensor

read this , it might help.

[ddezso]

Thanks. Any thoughts on the area circled in green? Seems odd to have to wires coming out that dont connect to anything.

[Pir0San]

you have a later Z thermostat housing on your motor, and because it is a '74, this makes sense. The original 240Z thermostat housing just has the one temperature sending unit, which a wire connector is connected to. Those wires don't need to be hooked up, as far as I know. My temp gauge was being erratic as well, but I figured out that it was the connector in red that needed to be replaced. You can get the terminal connectors from radio shack, and then just crimp a new connector onto the wire, and it should fix your problem. If you are concerned about the gauge itself, have someone hold your temp sensor wire onto a body ground, and turn the key to the on position. If the needle shoots up all the way to hot, then you know your gauge and wiring are good, but if it doesn't move at all, I would suspect your wiring first.

[=Enigma=]

The thing with the green wires is a Thermo Switch Assembly. This is used to determine when to open/close the EGR valve. One wire is a power lead that normally attaches to the wire loom near the coil. The other end attached to the EGR vacuum control & solenoid(smog stuff). Mine is detached as well. No worries.