I've just spent an hour looking through threads...but seems like there are a lot of different things that can go wrong. I'm hoping someone will have had this same problem and will know if it's an easy fix.
Just got my truck back from the mechanic who put in a rear main seal, new clutch, and also a new thermostat that i picked up at advance. it was a 180 degree one. but since i got it back i'll be driving and the gauge will go from normal (half) up to the left edge of the red and back down to normal. so i topped off the radiator and the reservoir but it's still doing the same thing.
I'm planning on picking up a new radiator cap and coolant temp sensor and see if that works. anything else quick/cheap i can try to correct this or figure out what the problem is?
Thanks

 

Could be an air bubble in the system. What do you have?

 

motor? 3vze (in the sig)

 

The T-stat, although new, could be bad.

 

My truck was doing the same thing until I changed the thermostat this weekend. I put in and Toyota thermostat stamped 88 degree C, seems to have corrected the problem.

 

Well, found the culprit, a steady stream of coolant dripping out of the radiator. it was coming out as fast as i was putting water in. i am hoping it was just something that didn't get sealed up right when the thermostat was changed.
Thanks for all the input, at least now i know how my truck reacts to a dry radiator

 

Yo guys rather than start a new thread for my same question ill jist ask here and see if its noticed lol. My runner was heating up about 3/4 the way up the temp gauge when pulling up a long hill and would so after cool off, it wasnt much of a bother except the anxious feeling of hoping it drops. But i had some spare time and decided to replace the t-stat to see if it remedied my "problem". replaced with a 195 gates t-stat that outta the box looked a bit different then the one i pulled from the engine(wasnt worried as the gasket fit in place fine, and i imagine design changes over time). With the new one in it does the same thing, maybe even goes a bit higher now than 3/4 but not quite to the red. Seems to be enough coolant as well. 5000 kms on new rad as well, no leaks. Any thoughts? Could the new t-stat be faulty?
Cheers
Kael

 

Hello 4runninmud..I just posted this in my 86 build early this morning.. I had the same thing happen on a 91 truck I had. Try cleaning you thermostat sensor. On a 22re it is located between 2 and 3 injectors. Has a blue connector. It probably has alot of green build up on it.

Also for good measure, try parking on a steep incline when motor is cold and remove radiator cap. What you are doing is burping the system. Getting trapped air out. Let it run and cycle the Tstat a few times.

 

Thats some great advice, ill look into after work today and let you know. Cheers