I just flushed the evil DexCool from my '98 LeSabre, replacing it with Prestone Extended Life (DexCool Approved, reddish color). I also replaced the 195 degree stock thermostat with a drilled 180 degree Stant, with a new o-ring and gasket.

I followed the directions for bleeding out air in Techinfo as well as possible, but I do have a question...

I know the thermostat is opening properly, because warm coolant does flow through the upper radiator hose once it gets up to temperature. But, how "firm" should the upper hose get?

Mine is easily squeezable...not a damaged hose, just that it feels like it'* half full of fluid and half full of air.

Is that normal? I would have expected more firmness.

Firmness depends on the pressure inside the system. Don't stress about it. Doesn't mean anything.

I think this might be normal, not sure how strong you or the hose is. You could check the firmness against a new one at the parts store. They do get softer as they age and the top hose does not have the wire wound within it for strength like the lower one does.

Also you'll have to bleed the air out for several days to work all the air out imo.

I have a "spongy" upper hose in my 95 Bonnie non-SC.
Been that way since '01(94,000 miles)
Just flipped 147,000 yesterday, no problems...

STILL like the car!!!
Bob

I replaced the thermostat and gasket in mine Friday, and the upper hose was soft at first. Tehn after taking it up and down the highway and doing some wide open throttle'* (WOT'*) the hose regained it'* firmness.

keep an eye on the coolant level and bleed it one more time at the thermostat. Any remaining air pockets should work their way out in time. Hose should be firm when the engine reaches operating temp or you may have a radiator cap problem.