temp sensor problems
 

i have an 87 supra turbo, and the temp sensor is acting strange, it bounces up and down depending on speed, and sometimes it doesn't act up at all. I have checked my coolant levels and there fine, the only times i have to add coolant is around oil changes. i have a new radiator and it never over heats. i am in some need of guidance. thanks

Make sure all your temperature sensor plugs are tight and all the wires are connected and not broken.

Second make sure you have a thermostat in your car. Usually if a vehicle doesn't have a thermostat it causes fluctuations in temperature.

I've seen temp gauges do that due to air in the system. Make sure when you burp your coolant system that the radiator is higher than your heater core as there could be air trapped in there. Put the front end of the car up on ramps or park it on a significant slope.

I forgot to mention one more thing. It could be a blown head gasket. Or early signs.

Is when you change the oil the only time you check for coolant loss, or is something going on when you change the oil which causes you to lose coolant?

Dune is right, you may have or be working on a bhg. Do yourself a favor and run a Block Test to see if you've got CO in your coolant.

No i check the coolant every week or so, but the only time i need to add any is around oil changes, i have just replaced my HG about 10,000 miles ago with a metal one. i checked all of my wiring and its still doing it, i think i may just flush the system and see what that does, its about time to do it anyways.

thanks for the help.

Did you get the block and head resurfaced before you installed the metal head gasket? Metal head gaskets tend to leak when not sitting on super smooth block and head. It might not be sealed well. I have no other explaination other than faulty wiring or broken temp sensors or gauge.