On my 01 Extreme radiator the drain plug is really tough to get to. Must I drain the coolant before doing the thermostat? Is there a how to on the thermostat or is it in the housing connected to the upper rad hose?

 

on my 02 blazer the thermostat was in the engine in front of the TB. you should be able to follow the top right radiator hose(when standing in front of your truck looking at the engine) to the exact location mine was a rubber hose into a metal hose. then to remove the hose to get to the thermostat just remove the two bolts(i cant remeber the exact size) and the hose will come loose and youll lose some fluid then simply take the old thermostat our and replace with the new one. so in my experience i didnt drain the radiator fluid, but you may have to throw some more fluid in depending upon how much you lose during the replacement.

 

Yah basically what he said,you will lose the coolant that is in the upper radiator house and a little from the top of the radiator. You might want to do a flush and refill if you havent done one recently since you are already opening the system up and going to have to add more back. I changed my thermo when I did my flush I first broke the thermo so it was open,then put it back along with the cleaner and let it run like it said,then flushed out with one of those hose connection tees you can buy that prestone makes. What is prompting you to change the thermostat?

 

I am changing it because I was told it would go bad soon. I just had an intake gasket put in and would like to knock it out. I have a new gasket, new hoses, new rad, so i figure the sooner I do thermo the better. I am hoping I would not need a flush considering I have lost all coolant twice in a week,lol.

 

ok yah if you have already changed the fluid twice in a week,you can just unbolt the thermostat housing and pull the old one and drop the new one. Then level off the coolant for the small amount you lose.