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Cadillac Repair/cadillac deville


My car is a 2000 and just bought it but its running hot so I went and got a new thermastat but now its back running hot so what's wrong with it could it be my sensor to the muffler and my spark plugs need to be replaced


Just answered for another person yesterday and told them not to bother changing the thermostat that everyone does and it is not the problem. Now, it appears as though you are looking for a simple single fix and I will tell you right now. That is not happening.

First of all, you have an aluminum engine. This means that when the temp creeps to 225 degrees or hot light is on, the engine is self-destructing-melting and very expensive repairs are imminent. Head gaskets go as a result of overheating and not the cause. Engine blocks will crack and break and heads will crack and warp!

This engine is not a cast iron 3.8 where it can be run with no fluid in the radiator for 20 miles with steam just pouring out of the hood. Your aluminum engine that hot would last a couple miles before cataclysmic destruction. If that temp gauge gets above 220 or that hot light is on, I do not care where you are or what you are doing, Shut it down immediately!

The other warning I will give you is that there are no good engines in the junk yard. They have all been overheated, meaning if the engine is destroyed, you need to go with a factory crate engine for $4k and change.

Cadillac should have been required to put a warning sticker on the dash "Do not Overheat" but then they wouldn't have been able to get the big bucks for them either.

With that said, the answer could issues to numerous to list, but I will get you started for now.

To give you an idea as to how sensitive these cooling systems are and how small the water jackets are that keep the engine cool, all one needs to do is accidentally leave some old residue of the sealant or gasket from the water pump and this debris will plug the cooling jackets and the engine will over heat.

Now, I won't rule out  computer or a sensor issue because that just adds to the mix. Here are the basics you need to check first: Is the fan or fans operational? You can check by putting the a/c on or defroster with the key on. The engine does not have to be running. Once you do get the engine warm, put your hand on the top of the radiator, the bottom and sides in the honey comb. If equally warm good. If not there is a circulation problem in the radiator and needs to be flushed or replaced.
When is the last time the radiator was flushed? If over 5 years, coolant/anti-freeze breaks down and will leave residue inside the engine and radiator.
Now that I went back and looked at your statement that you just bought the car, this makes me a little nervous, because the seller could have had this problem and doctored it up to sell it. I have seen this all too often!
I would recommend taking the car to a repair garage (not a dealer) to check some things. Have them take a good look at the coolant. They may find where someone put some coolant system sealer in it. Have them do a coolant pressure test and check the head gasket area for leakage. If they were leaking before, the pressure tester will determine that most likely, plus the block will have trails if an external leak. Have the radiator cap tested. Has to be good for 15 pounds or coolant will not circulate.
Personally, I would be looking for a problem that the previous owner had.
I love Cadillacs. Have owned over 20 and have dealt with the Cadillac aluminum engine since it came out in 1982.
The aluminum engine is great on mileage and performance, but the weak point is overheating. This vehicle could have a bad water pump missing a fin or two. Rare, but it does happen.
I am always suspicious of a used Cadillac that has been bought with an overheating problem, because this could have been the reason it was sold.

Try some of my suggestions. If you still have issues get back to me and I will try to help.

Good Luck.  

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Rob Painter


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?


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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