I need some assistanace. I have a 1992 Tercel 155, 000 miles. My temerature gauge has recently started going beyond the 1/2 mark. It has not actually overheated yet but I checked my reserve and it was almost empty, I filled up to the appropriate line and it's been staying there since. But the gauge still goes up to the 3/4 mark. I'm not sure what's happening. Any suggestions??? Thanks

You may have a bad temp sending unit.
Someone correct me if I'm wrong, but I think it's on the right side of the engine (as you standi in front of the car) near the top, possibly screwed into the head. Bad sensor would show the car as hot, even if it wasn't.

I had a similar problem with my 82 Tercel. Turns out that my headgasket was leaking exhaust gases into the coolant. I immediately ordered the mech to repair the gasket because if it blows completely then the coolant will contaminate the oil and the engine will be damaged severely. I would have answered your post sooner since I had the same problem but I didn't understand what was happening only till recently. You can diagnose this possibility by getting a compression test done on the cylinders. If any of them is low, you can bet your problem is similar to mine. Hope this helps.

keep an eye on your coolant level...if it continues to go down and you are not leaking it out on the ground...it means head gasket leak, thats why the higher temps.

We had this problem with one of our cars, not a tercel however...and found out it was a leak. Wow, 155,000 miles and still running, that is great!