Thank you all for your advice. I have not been able to change the coolant yet. I am picking up a new stock thermostat tomorrow from Toyota.
But this is what i think might have happened. 2 summers ago, almost 3 now I drained the fluid out of the radiator which used to be Red. And added in the Longlife pink coolant. Not all the Red was drained because at the time I did not know to drain the block to. That means half the old fluid is still from the factory. (2001 HL) That must be what has caused it to become gunky. When i look into the radiator its fairly crusty inside and the fluid is a dirty pinkish red color with a thin layer of "gunk" floating on top.
Anyways, with the recomendations, this is the plan. I'm going to drain the block and radiator and also clean out the reserve tank.
Then pull the old thermostat out, fill the engine back up with distilled water through the thermostat housing, and fill the radiator. Then start it without the thermostat and let it run for about 20 minutes.
Then drain it down again. install the new thermostat/gasket, Fill the block through the thermostat, and proceed to fill the radiator up. Start it with the cap off and check the levels and add until the level is topped off. Put the radiator cap back on the radiator and fill up the reserve tank.
I'll be using the Toyota Pink Coolant......
Hopefully this will clean the system out and prevent any further damage.... I hope
