Expert: Rob Painter - 9/13/2010

Question
I just bought a 98 cadillac deville it was running fine
until one day when i was going about 70mph on the highway
(with the a/c on) and the engine began to quickly overheat (
it usually runs about 210 degrees..) . it jumped from 246 to
260 in a matter of maybe 20 seconds. Since the incident
anytime i drive it anywhere longer than 10 minutes the
engine heats very quickly and then holds steady at 244
degrees. also, i just filled the coolant 3 days ago and my
check coolant level light is on again. i have not seen any
coolant leaking from the car while it is in motion or when
it is parked. any thoughts on what this might be?

Answer
Hello,

I answer an average of 2 questions a week on engine overheating.

These aluminum engines since 1982 can not be overheated without doing severe engine damage to them. I commonly put up warnings--DO NOT OVERHEAT THIS ENGINE!

Have you removed the engine oil dipstick to check the oil? If it is milky in color, you blew a head gasket, cracked a block or warped a head- all of which are big bucks to repair.

Is there white smoke coming from the exhaust? If so, the same diagnoses comes into play.

Here is the problem: This issue is so common that you cannot buy used junkyard parts because chances are about 99% that the engine was overheated and is junk. This leaves you with one option-New parts!

Years ago in the cast iron Chevrolet engines, we could run them hot. You have an aluminum engine that self-destructs past 220-230 degrees.

These engines have so many reasons to overheat, it is hard to nail down a specific reason. Bad cooling fan, thermostat, radiator,water pump plugged cooling system etc.

I love Cadillacs. Have owned over 20, but the one problem a person can't live with is an overheating issue.
Cadillacs are a great car as long as there is no overheating. Once that happens, repairs can go past $4,000.

Here is another problem: It is the chicken or the egg. Say you find a bad radiator and replace it. That no longer will fix your problem because the engine has overheated causing you more issues.

What you need to do is not drive the car anymore and have the engine and cooling system checked out. If you are real lucky, you didn't do major engine damage, but from your description I think you did.

The engineers at Cadillac in my opinion knew about this problem and some good attorney should have started a class action long ago.

Jeep was forced in 1985 to put a label in the vehicle warning of the roll over potential. Cadillac since 1982 should have had a warning label "Do not over heat or serious damage could occur."

Un fortunately you and all the other aluminum engine owners never were informed of this money making plan from Cadillac. Worse yet, I don't even know if GM can be sued anymore because they are owned by the taxpayers.

As I stated, these are a great car, but can turn into a money funnel quickly!

If my answer helped you into making a decision, please rate it. Thanks