I had this problem in the past, I believe the sensor on the fluid bottle has stop working or the connection maybe corroded and it may need cleaning. I do hope this hepls your problem. Nibbs
headgasket leak and exhaust gas is getting into the coolant
Run a pressure test on it.
Whats the normal temp for 1996 Cadillac devlle
Once you have all of the air out of the system, you can drive it immediately. Fill the radiator with coolant, set the heater to hot and start the car. Watch the coolant level and keep refilling it until it will no longer take any more coolant.
11 litres. Use 5 litres of a gycol type coolant mixed 50/50 with water. Be sure to run the motor until its warmed up after replacing the coolant to ensure all trapped air has been removed.
Sounds like you have a coolant leak. When cold, put a pressure tester (hand pump with fitting to the radiator neck) and see if you can see any coolant leaking. Once found, fix the leak.
Check the coolant fan see if it turns on when the engine gets hot. if not then your temp sensor could be bad
Sounds like a blown head gasket. Have a mechanic do a compression test, and check for oil in the coolant and/or coolant in the oil, (white foamy material around top of fluid level.)
If it is leaking next to where the lower radiator hose attaches to the engine, the water pump has failed. That hole is the water pump weep hole.
instead of putting fluids in over flow put it directly in the radiator. take cap off radiator start car and wait like 5 minutes then add to radiator until full. OR on the top of the water pump there will be a brass fitting with a small brass bolt in it, loosen the bolt to allow air to be pushed out of the cooling system as you add coolant, otherwise when the air in the system gets hot it expands and pushes the coolant back out and the car overheats. when coolant starts coming out tighten the bolt again and run it up to operating temp.
Sounds like someone mixed the new 'dexcool' and the traditional green coolant together. I would IMMEDIATELY take your vehicle to a reputable shop and have the cooling system completely flushed. They will ensure to install the correct coolant type.
sounds like a blown gasket, allowing coolant to enter the cylinders.