Howdy,
I'm about to take my prizm to a local mechanic (the dealer says they can't look at it for a week or so and I'd like to have it fixed by then) with what to me seems a strange problem.
Driving on the highway (in 100 degree weather), after a while, the gauge will begin to rise to about 3/4 of the way to overheating. Then, it will drop back down to normal. Then it will creep up again. It rises fairly rapidly but doesn't "shoot up.". Then, it goes back down to normal again ... and up ... ad nauseum.
If I'm in town in stop-and-go traffic, once it rises, it won't go back down like it will on the highway. It never hits red, but going 3/4 of the way isn't happy-making. The car is about to go on a thousand mile trip and I definitely want it to behave better before doing so.
What's the deal? (It's not low on antifreeze or oil.) A bad thermostat? Something horribly expensive? Any hints before I take it to the mechanic would be most helpful.
Thanks and best regards,
Jeff