My wifes 94 4-Runner has over heated a number of times in the last week. It is a V-6, automatic with 196,000 miles. I replaced the anti-freeze with Toy red about 6 months ago. I put in a new (not Toy) thermostat the first time it overheated. It only overheats when she drive to our house from town which is an elevation change of 2500-3000ft in 3 miles. She had the air on but turned the heat on half way up the hill to cool it down. The needle had gone almost to the top of the gauge but fell back to about 1/8" above normal with the heat on. I origianlly thought it might be the water pump but it runs fine on level ground at cruising speed. This leads me to think it is the fan clutch. If there is enough air flowing over the radiator when the engine is not under load it stays cool. But going slow up a steep hill it overheats. Does this sound correct? The fan clutch seems to have good resistance, but that may change during driving when it gets hot. Another question is, do all 3.0's have the fan with a ring built onto it as mine doesn't.
Thanks, Chris

 

sounds like it could be the fan clutch. you might also have a bad water pump if the radiator won't stay full. easy way to check is crank it up then look for any kind of water/antifreeze getting sprayed by the water pump. if it's not this and you're pretty sure it's the fan/fan clutch... instead of getting it fixed, i would swap in an electric fan. i've just finished the work on mine and i could tell you exactly how to do it and send you a couple of wiring schematics that i've experimented with. the electric fan is a good upgrade on the 3.0 engine. helps give a few HP and it'll stay cooler at idle. just my .02

 

You might want to have your head gasket checked as well. When mine went I was stuck in rush hour traffic, but once I got going it cooled down.

That is also a recall item, check with your local dealer and you may get a free repair