On my 96 Deville I changed the radiator two weeks ago after detecting a leak (yes...on the right side just as was mentioned).

The "low coolant level" message came on which is why I looked to find the leak. Now two weeks later with the new radiator, hoses, sealant, and some "Kool It" conditioner it started running hot today. The little red thermometer idiot light came on so when I checked the information center for the coolant temp and it was running about 250 degrees! All the way way home if fluctuated between 225 and 250 degrees. When moving it cools back down to 230 or so. But sitting in traffic climbs right back to 250 quickly.

Seems too hot to me buts it also seems to be running OK. I was thinking maybe a water pump? Fan not coming on? It just turned 50 thousand miles.

Does anyone know what is the "normal" coolant operating temp for a Northstar on a warm (90) florida rainey day with the AC on?

Thanks in advance.......

Normal seems to vary a bit from 198-220 or there abouts. Mine runs 206 in the summer and 213 in the winter. Do a search. there is a lot of info. Check the water pump belt tenioner, purge line, pressure cap, coolant mix, thermostat.

Check the electric fans. If they ain't running, you will overheat when stopped in traffic. When you are moving, enough air pushes in the grille to keep the temp down, but you need the fans when stopped. Fans are mounted on/near the radiator and maybe they got unplugged when the radiator was changed..


David Starr

Your fans should come on around 225-230. They should also come on rifht away if you turn the A/C on.

240 at times can be tolerated, however beyond that I would be REAL careful.

I know, not real helpful.

When I'm driving it goes to 191 ~ 199, stopped in traffic sometime goes over 220, but never over 230 I believe. If your car starts to overheat, can't you turn the temp to 90 then set the fan speend to high to help it cool down?

"Kool It" conditioner? I don't remember seeing that anywhere in the service manual??? Only GM Pellets should have been added to the lower radiator hose.