No heat on my 98 caddy deville delegance?

Partially drain the radiator (drain is at the bottom on the driver's side of the radiator - you need to remove the front air deflector panel underneath the car to get at it). Remove the air cleaner assembly. Remove the outlet hose from the thermostat housing (this hose is the one attached to the top of the radiator on the driver's side - it is NOT the inlet hose which is routed across the top of the radiator). Remove the bolts holding the thermostat housing to the water pump, then the thermostat and gasket. Carefully clean off any gasket material from the water pump and housing, install the new thermostat and gasket, and reverse the procedure. Make absolutely sure you install the thermostat correctly - in must be installed in the same orientation as the old one.

Northstars are notorious for having head gasket issues. I can not be sure without having the car in front of me, but I would suggest having them checked by a reputable shop. This is not an easy, or cheap job to have done.

Run the car without the thermostad to see if it still overheats. If so check the heat sensor it might be faulty.

I bought a 2000 caddy Deville off the side of the road, had a 800.00 sign on it, pullover to see it, a man came out and said he had it to four shops and they can't figure it out. gave 700.00 for it and had to tow it home., flushed radiator, heater core, and engine out, changed thermostat, checked water pump. this Northstar engine would over heat when driving it. Turned out to be the plastic cover underneith, it hooks to the front bumper and goes to the metal frame to block the wind. when it is missing, the wind blows in and back drafts the radiator so the fans can't do their job and cool the motor. a five dollar cover from the junkyard and it was fixed, crazy hu. I hope this helps someone.

Assuming you have the Northstar engine....

The thermostat in the northstar engine is located at the bottom radiator hose (unlike most conventional cooling systems), the hose connects into the housing where you will also find the water pump.
Remove the hose from the housing,then remove the two bolts on the flange,the thermostat can then be pulled out.
Take note of the orientation of the thermostat as you remove it.
Don't forget the new gasket when you install your new stat.

flush your radiator first.with the thermostat out you should see the water moving if not bad water pump.this engine needs the thermostat to function properly and either a 50/50 coolant or straight coolant so it does not boil over.also make sure your fans are coming on

Your radiator might have a clog and needs to be flushed...also check your water pump to see if its working right.

You likely don't want to hear this but Northstar engine a common for head gasket failures. One good test that I use it to fill the coolant tank all the way to the top. Then start it up. If the coolant shoots out of the tank. The heads have a problem.

hello i have a 1998 cadillac deville course. an i been having the same over heating problems with mine i been taking it to mechanics an no one seems to know even the caddy dealship its overheating i checked the termostat water pump radiator all hoses was wondring could you tell me what you did or what you are doing to fix your problems my email is [email protected] thank you very much

head gasket failure