What you need to do is next time the engine is at operating temperature and you are letting it idle, get out, open the hood, and use your hands to compare the temperature difference of the upper and lower radiator hose. This will tell you if your radiator is working. The upper hose should be so hot that you can not leave your hand on it for more than 1-2 secs (apprx 190° F), but the lower radiator hose should be warm enough that you can leave your hand on it for nearly 5-6 secs (apprx 120° F).
THERE MUST BE A LARGE DEFINATE NOTICABLE TEMPERATURE DIFFERENCE in the two hoses!! If there are not, then, as my first advise, your radiator is plugged and needs to be taken to a radiator shop and flushed.
As for your headgasket and your water pump, just ignore those for right now. I wouldn't want to assume its those so neither should you
But for future reference, there are two ways to check a bad head gasket: 1) Inspect for moisture in your crank case by looking for any moisture under the valve cover cap, and 2) run a compression test on the engine. As for the water pump, the only way to really check it is to pull it off and inspect the timing cover for wear. There needs to be considerable wear on the timing cover in order for the coolant to begin cavitating behind the pump. This is usually not the case but its still a possibility.
If I may ask, what brand thermostat are you using? I have put in a perfectly good brand-new out-of-the-box Stant thermostat and it was junk the first time I went out for a test drive. I hope you and everyone else who reads this ONLY uses Genuine Toyota thermostats. You will thankyouself later
The way to test your clutch fan is to wiggle it back and worth (With the engine off) and if you feel resistance, then it is good. You may need to wiggle 4 or 5 different fans at the same time to gain an understanding of how much or how little resistance is acceptable, if you have never done this..
BigMike
