OK let's pretend that I'm not on about the MR2 here but I know that you guys are up for a challenge! LOL :)

 

Right, car doesn't lose any coolant, convinced that coolant is being circulated around the engine in the correct manner...however...my temp guage sometimes reads cold all the time, then other times it has some inspired motivation and reads closer to where most jap cars temp guages should be.

 

Scoops reckons that my thermostat could be on the perm open setting.

 

Could it be the sensor?

 

TIA

I had a prob with my temp guage...read fine until I accelerated hard...wierd

Tracked it to the temp sender, dodgy connection, (thanks to some help from here).

Could be that you have an airlock somewhere in the system.

To eliminate this take rad cap off (first)...run till ferking hot ...squeeze a few hoses when warm to help force the little ferker out...bottom rad hose usually gets it on the move)....no bubbles no air lock.

Reckon if it was the Thermo then it would happen all the time but who knows?

Good luck!!

I use to have this when I first bought my Z Timmy. New Thermostat sorted it!

Thermostat as said above

 

if the needle starts hitting the roof and bouncing down to normal that indicates there is air in the system and you are loosing coolant. The thermostat isn't to big a job though,