Hey Scotty, I have a 93 Celica and I suspect my thermostat is not working right. When driving from cold, car warms up normally, temp goes to the middle and stays there but when going downhill (doesn’t matter if cold or hot outside, heater is on or not) the temperature drops to about 1/2 on the gauge and there stops moving and temp doesn’t drops any further even with heater on. When idling for several minutes (at stoplights for example) and when I get going, the temp drops to 1/4 - 1/2 and moves in that area depending of outside temperature and load but once hitting 1/4 on the gauge it goes back to half (like if the thermostat opens when idling but doesn’t close again until coolant gets too cold in my case 1/4, like the thermostat is sticking). If idling for very long, radiator fan turns on and then off again (while doing so, temperature doesn’t move from 1/2) so everything good there. Is my suspicion right and I should replace the thermostat or not yet since it is somewhat regulating the temperature just a bit late? Even when temps got in the negatives, temp rises to 1/2 and stays there. Thanks

replace the thermostat.

@ScottyKilmer Thanks a lot. I wish i were in Houston or you were in Europe so you could fix my cars