[quakerlt]

I've tried searching through the forums but didn't find similar problem. I wanna some advices, if possible.

I've rebuilt the engine 500km ago (~300miles). And today, while driving, may temp gauge started to raise. When it reached 80-85% I've stoped the car and checked coolant -- overflow bottle was about 80% full (when I've filled the radiator with coolant, the bottle had about 50% of fluid), so there is no leakage or other major problem with that.
So, I've tried turning ON hot air in the interior -- it worked! The temperature decreased until 1/2 of temp gauge (as usual).

So the problem could possibly be thermostat, right? Or could this also be fan clutch? After driving and turning off the engine, I can move the fan clutch with my hand, but it isn't free-rotating. Is it still good?

I dunno, I'll try checking the thermo tomorrow... Any other advices or solutions?
Btw, I have 1990 turbo.

 

[quakerlt]

If the engine is running idle... lets say 800-1000 rpm can you stop the fan with a thick piece of wood ? (without jamming it in there, just slightly move it into it's reach and see what happens)

If it's really easy to stop, your thermal "clutch" is malfunctioning, replace it. If it's not all that easy to stop, the clutch should be fine. You should check the thermostat and radiator(hoses) next.

Yes, I've found that checking method. I should just start my engine, grab the thermal clutch, and when the engine will be warm enough I won't be able to hold it. That's one of my friends' suggestion (he experienced it on his supra). I'll do that tomorrow.