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Cadillac Repair/2000 Cadillac Deville (DHS) 124,000 Miles

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Expert: - 7/18/2011


Question
Okay, I have a 2000 Deville and on a250 mile teip it ran hot ( idle engine turn off) I idlesd engine for an hour got back on the ighway and it ran perfectly..While driving i noticed if i went above 70 mph the temp gauge would creep up when i slow down it would go back..So i made the trip safely and the next thing i done was change the waterpump, thermostat and the radiator had been been replaced months before..That was the first tine it had ran completely hot... After i finished changing everythng i got back on the highway to test it and it ran okay until i turned on the AC then.up to 70mph it ran hot agaian but not totally because i turned it off..Lon story short city driving even with AC it wont run hot but the minute i get on the highway up to abt 70mph it runs hot again... Whats the problem??

Answer
Hello,


My guess would be circulation. You may have a restriction in the cooling system and what is more than common is people changing water pumps on these engines inadvertently get old gasket material inside the engine block either at the water pump or through replacing a thermostat. This aluminum engine has very small water jackets that are easily plugged.
Heads crack on these engines and head gaskets blow causing either coolant in the oil or white smoke.

Have the system checked with a pressure tester. Should hold a steady 15 pounds. If not, you have some sort of leak and since you don't have correct pressure, that too affects circulation.

these are a great engine, as long as they are not overheated and then they self destruct.

The most common issue I see is remains of gasket material in the engine and you would find it as soon as you pulled the water pump again.
You complaint is consistent with some sort of engine circulation problem. I can tell you that for sure.

Let me know what you find.

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Rob Painter

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Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

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Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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