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Cadillac Repair/cooling system..1989 eldorado


My 1989 eldorado seems to run hot...I put in a new radiator...It seems to run between 210 and 235 in city driving with the air on. when I start the can, neither fan is turning...Is this normal? I am a pretty good "wrench"


running with the temperatures you discuss lead me to believe that you have very serious problems internally with this engine, and I do know what I am talking about, having serviced Cadillacs for 3 decades, owning over 20 and addressing overheating issues on the Cadillac aluminum engine for over 10 years.
You may be a good tech,however from your description here, it appears you are not familiar with the over heating issues in the aluminum Cadillac engine that was first introduced in 1982. Names were changed, cubic ccs over the years, but the same problem existed. One is pushing their luck with the temperature over 225 degrees when the engine literally begins to melt internally and that is where you are at. At minumum with the engine running this hot, you need head gaskets and chances are very good that the block is cracked. The most likely reasons that the fans are not coming on is either there is not enough coolant in the block or it is simply not circulating due to internal engine failure. This engine is aluminum, not cast iron. Pistons can melt, the engine block can crack in the cylinder, heads warp and a whole bunch of ugly things happen from overheating and you state that it goes far past 225 degrees.  
Better yet, you will not find a good used engine because the primary reason these cars are in the junkyard with no body damage is that the engine was overheated. GM was selling a brand new crate engine for $4,000.00 if they are even available any longer.

This engine is so sensitive to heat, that if the hot light comes on and engine is not immediately shut off, catastrophic damage to the engine is imminent!
The first thing I would recommend is use a cooling system pressure tester to see where the leaks ate. Check externally of course. Check the oil for the milky color and also check the exhaust for white smoke. Something serious is wrong with the engine running over 225 degrees.

It really does not matter as to what skills the mechanic has in this case, because unless he knows these aluminum engines like me that has lived with these problems (many Cadillac techs have) a general mechanic is not going to be familiar with the Achilles's heel of the aluminum Cadillac engine and overheating. There is no forgiveness.

These engines are plagued with cooling system issues. Water jackets that are too small, in which a piece of old gasket material left in the engine can plug the cooling system. A bad radiator cap that causes lack of pressure shuts off circulation of the coolant, water pumps in which the impeller blades break off, and the list goes on and on. These engines were light weight and great for performance and mileage, but if they run hot, say goodbye to the engine and even the car because it is going to cost far more to repair than the car is worth.

I hate to be the bearer of bad news here, but the temperatures you describe that this engine is running at, are unheard of for this engine and I really am surprised it is still running.

I have had cast iron engines I have run at these temperatures and never even blew a head gasket. I was lucky. Aluminum engines are melting. If you ever have a bonfire, put a soda or beer can on it and watch it melt. This is your Cadillac engine above 220 degrees.

At the moment, figure for the worst and hope for the best.

Let me know what you find and I sure would not count on the reliability of the vehicle.

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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