I have a 96 DeVille and it had the same problem. What turned out to be wrong was that my car has 2 fans, 1 should come on when start the car and the second comes on when the engine is under a heavy load (ex. stop & go traffic, a/c running on a very hot day). My primary fan wasn't working properly and I had to take to the shop to correct the problem.
that sounds definitely like a water pump,without a doubt. Ck electric cooling fan operation Could be a defective thermostat. Simply have it replaced (cheap to replace, and it may be your only problem). Good luck. The other answers are all possible, but my suggestion is the most basic, and the usual first item to check. Unfortunately the two previous answers will not cause the coolant to spew out when you shut the engine off. The only thing that will cause that is excess pressure in the cooling system. Just about the only thing that will cause that is a head gasket. Most Cadillacs from the early 80s on have aluminum heads. It is very common for an aluminum head to become warped when the engine overheats. When this happens a crack can form between the head gasket and the top of the cylinder block allowing pressure to get into the coolant. This in turn may cause a coolant hose to expand and allow coolant to spew out, it can also cause the radiator cap to release coolant, a good radiator cap is designed to release pressure when the pressure goes above the designated psi. The fact that it is not boiling over while running indicates that most if not all the rest of the cooling system is allowing the water to flow. The most common cause of overheating in engines is that the thermostat gets old and sticks. It only has to stick one time to cause the engine to over heat enough to either damage the head gasket or even cause a crack in the cylinder head. Take the vehicle to a garage and have them do a pressure check on the cooling system. After they have applied pressure to the system they will allow the engine to cool for a short while. If the pressure drops very much they should then remove each spark plug in turn and check the cylinders to see if coolant is in in them. If so that is the evidence that the head gasket is bad. If there is coolant in the crank case oil pan also, that indicates that either the head gasket is completely gone or that the cylinder head is cracked. Depending on your eographical location it could cost around $1000.00 or more per head to have the heads milled and the head gasket replaced. If the car is over 8 years old or has more than 100k miles on it you will be better off to have the water pump, timing chain, camshaft and crankshaft timing gears replaced at the same time. Depending on the cost of such you may wish to check with someplace such as Dr. Motorworx to have the entire engine replaced. It can sometimes cost less to do that. And these shops usually not only guarantee their work, but usually give anywhere from 1 to 3 years or 36k warranty on the engine.
I had the same problem on my 95 Deville and you will not believe how simple the solution was. I discovered it by accident. The battery died and I swapped it out. After removing the battery, I noticed the hose that leads from the reservoir to the radiator had been pinched by the battery. I straightened it out and made sure it was not pinched by the new battery. The car never overheated again, problem solved.
I had the same problem my car would spill antifreeze but it appeared my radiator was full of gunk so they clean it up and i have not had a problem yet i was glad it was not a head gasket
ANSWER after a car stops moving and you turn it off the temperature will increase as much as 15 degrees causing more pressure to develop in the cooling system could be a loose hose clamp but more than likely its the water pump they leak more when not pumping in my case it was both on my 98 deville
if fans are working and thermostat is good welcome to the world of northstar famous headgasket/faulty headbolt and stripped block crap engine problem
Sounds like a blown head gasket
It sounds like the antifreeze / distilled water mixture is freezing because the antifreeze mixture is too weak for the outside temperature Usually the antifreeze and preferably distilled water mixture is 50 / 50 ( Ford states to not exceed 60 % antifreeze )
Soundsw like heater core is going bad. You will smell antifreeze prior to actually noticing water/steam leak
Bring to a shop and have system pressure tested to find where problem is originating
AnswerIs the system overfull?, Is your gauge working?I had the same problem and I had to replace the head gaskets.
when overheating occurs at highway speeds the cause is usually. a radiator or coolant circulation problem, Check for a restricted or clogged radiator.
Dont use barsleak use a chemical called therma weld it work perfect for me its about 300$ and worth it!!!!
Dirty or plugged radiator Water pump Defective radiator cap Thermostat Cooling fan not operating hoses collapsing
Cadillacs are notorious for blowing head gaskets. You may want to look into that.
hardware problem hardware problem
The most common cause of overheating is a thermostat stuck in the closed position. However, other causes are: faulty water pump, clogged radiator, clogged hose(s), coolant leak or a broken drive belt. I had a 1987 legend with around 160K that was overheating. Antifreeze would boil out of the overflow. I changed my radiator and it fixed the problem.