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Cadillac Repair/1987 cadillac coupe de ville

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Expert: - 7/1/2010


Question
purchased car and ran fine while test driving it . We drove it for about an hour then suddenly the engine started to knock . within a few minutes the knock went away and now it is missing profusely , Help . what should I do . is it ignition related ? fuel related ?

Answer
Hello,

the key word is you bought it used- buyer beware.

You don't want to know what I have seen over the years to temporarily doctor a problem car just to get it down the road. Banana peels into a cylinder to take away a knock, trAns leak stop to the power steering, coolant leak stop to cover a bad head gasket.  Lots of crooks out there selling cars.

If someone is buying a used Cadillac, it needs a 2 hour test drive! These engines are notorious for being junk from overheating issues.

Since it is used and I am not at the car, I am not going to guess on a diagnoses. I recommend taking it to a repair center (not Cadillac) now and they can put the diagnostic equipment on it and tell you exactly what is wrong and pray the problem is not caused and covered up from overheating.
If the engine is bad you cannot go used because you will get the samge junk. If so, a new engine will set you back an easy $4k.

This is worse case scenario and I just want you to be aware. Hopefully the problem is not serious.

If you look at my archives, you will see just how common overheating is in these aluminum engines. I would rate severe.

I owned over 20 Cadillacs. I love them, but they can be a money pit.

I traded my last Cadillac off last year for a Chevy.

Good luck!

Cadillac Repair

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Rob Painter

Expertise

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?

Experience

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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