Originally Posted by WildBill
'97 DeVille, Northstar engine.
Anybody ever changed the thermostat in one?
Where are they and how hard are they to get at?
It's on the lower front of the drivers side in these FWD installations. It is inside the waterpump housing cover, which can't be seen 'cause it's under the airbox. It, the intake air pipe, and bottom radiator hose have to be removed to expose the housing cover.
This engine will have DexCool in the cooling system. While many parts stores sell other stuff they claim will mix with it, DON'T. Get fresh DexCool for the refill. This stuff turns bad if slightly contaminated with anything it seems. The other problem will be burping the system, you've got to be patient and get the air all out or the DexCool will go bad on you. If it goes bad it eats anything that looks like aluminum till it's oozing out everywhere, I kid you not!