First I wanted to say hi to everybody it's nice to be part of such an awesome forum. I own a 1982 280zx turbo that is completely stock as far as I know. And now the question, my temp gauge sporadicaly jumps from cold/mid to extremely hot somedays and others it stays mid. I already read quite a bit of past post, with some gained knowledge, but I am still unsure. I checked all the usual items when it comes to overheating such as the fan clutch, radiator flow, new thermostat, and water pump. They all seem to be working properly. The only thing I can guess is possibly a faulty gauge. The overheating also happens within a mile or two of driving, that seems to short to overheat to me. What is your opinion?

 

Loose or corroded connection's can cause this. Check them all including the head Temp sensor just for kicks. It's located between the #5 and #6 spark plug. Right on the head. 2 wire plug. And welcome to the site.

 

Welcome to ZDriver!

Proper coolant level, working thermostat, clean radiator, clean water pump... they are all part of a balanced diet, er... cooling system.

If the temp is really fluctuating that much (especially getting hot in the first few miles of driving) it sounds like the thermostat is sticking. That would be the first thing I'd replace.

 

maybe even the water temp sender, or a blocked radiator, check that too...maybe even a blocked coolant passage? donno. oh and welcome, and the sensor i'm talking aboot is by the thermostat housing, i don't no what its called...oh and welcome.

 

Thanks for the extra ideas, I just replaced the thermostat a few weeks ago, so I hope it's not the problem. For example what the gauge does, I drove one mile exactly to the store and extra hot reading, get out of the store drove home mid level reading, weird? My radiator is pretty dirty and my coolant which I replaced with the thermostat is already dirty, I'll change that again. How can I check if the radiator is blocked?

 

does the needle jump quickly from one position to another? Too quickly to actually be changing with the temperature?

 

Yes, it jumps from one point to another rather quick. It just bugs me how sometimes it acts just normal, other times not.

 

a way to check to see if the gauge is bad is to disconnect the wire that connects to the thermostat housing, and ground it against the body of the car. If the needle jumps all the way to hot, then the gauge is in working order. If it doesn't jump, then that means that you either have a problem with the wire leading to the gauge, or the gauge itself.

Good luck.