My car over heated twice the other day. My temp guage does not work. New sensor. New wiring. And I've replaced the gauge, still no luck. But when it overheated. the gauge magically started working, true it was pegged out past the 270 mark. but it worked. until it cooled back down.

 

Mines does that. but right at like 160F Its just a stupid air bubble in the T stat housing is my guess.

 

Fubar,
What temperature thermostat are you using?
Are you running the stock clutch fan or electric?
Are you running a 50/50 coolant mix?

As for the gauge not working, have you checked the resistance / continuity on the temp wire? I have kind of a similar problem on my 280zxt... the oil temp gauge used to work perfectly, but ever since I drove it home from MSA 07, the oil temp gauge spikes really high... like 300*F when the oil temp is actually 200*F (I checked numerous times w/ an infrared thermometer). After replacing the gauge & sensor, I figured it could only be that the wire is burnt somewhere in the loom, making the resistance different than it should be.

Anyway, make sure your thermostat is opening (and is a low temp opener). Also get an infrared thermometer & check the temp coming out of the thermostat housing, vs coming out of the lower rad hose (there should be quite a drop).

 

OEM thermo. Stock fan. 50/50 mix. I was having over heat problems when a dagum pin hole showed its self on th passenger side coolant line. water emptied the block. and whala, overheat.

 

hows your rad flow? if its got a plugged core or lower tank, it wont cool when really needed

 

seems ok now. It all started when a papper towel (brown thick kind) was discoverd trying to be sucked out the rad into the engine. blocked all flow. but now thats gone. I got a blown headgasket, and no working thermo. I guess i'm lucky, I only warped the head enough to loose compression on 4,5&6 once the engine is above norm operating temp. no fluid mixes.

 

Someone else has my thermo expansion problem eh?

I met someone with a beautiful 240Z who has an L28 Head. I needa check mine before i get on that.

Who would know what to look for on the head to tell if its warped? I'm almost sure I raped the thing, as I HAD to drive about 20 minutes past 270, poor girl =(

I wanna give her a nice homecoming.