My '99 DII never overheats when I'm driving her. Recently though she overheated while I was at an idle( for several minutes )and I had to have the cooling hose replaced. My father in-law suggested I change the T-stat out, he said when a vehicle overheats it tends to reck havoc on the T-stat. Would like some opinions...Thanks - RR.

 

Did you blow the radiator hose?
The upper one I am assuming?
Your t-stat is different from the ones your dad is talking about and overheating it will not hurt it.
Yours has a spring inside it, the old style (from his day and age) had wax in them and if overheated the wax would melt completely and come out of the t-stat and it would no longer work.

 

My mechanic said it was the " cooler hose " not on top, not on the bottom. Brand new serpentine belt, water pump about 4 yrs old, this past Nov I had the rad flushed & pressure tested. Would you suggest I still change out the t-stat? Thanks - RR.

 

Try it, its cheap and easy to do, I dont think that is your problem though.

 

Honestly, I'm all ears Spike! - RR.

 

With the DII the cooling system is designed so that when at idle the t-stat sends the coolant through the heater core and NOT the radiator.
If the t-stat is bad it wont open at all at idle and the truck will over heat.
The DII t-stat works on pressure not heat like the old style t-stats.
Replace the t-stat to rule that out, its cheap and easy so lets not forget the easy stuff.
If it still overheats at idle after that then we will have to go from there.
Could be a clog in the heater, could be a bad water pump, belt tensioner, almost anything.
The DII cooling system is very complicated and hard to diagnose.

 

Fan Clutch

Steve

 

Thanks everyone! I'm getting tired of putting money into her...Hey Steve, your in Troy I'm in Mt. Clemens, know anyone looking for a solid( albeit overheating) LR? - RR.