In the mid-90s, I had the misfortune of being "sold" an 85 Sedan-Deville with about 104k miles by my brother, the used car salesman. Fortunately, he also "sold" me the extended warranty, which is usually a waste of money. Within months of purchase, the serpentine belt broke. After having the replaced, the car overheated within minutes of starting. Apparently the water pump got damaged with the belt and would not generate enough flow through the radiator that had been clogged up with an after market additive. Having paid for the belt out of pocket, I sent the car to the dealer for warranty work. After they installed a new radiator and water pump, I drove off and it overheated as soon as I got on the freeway. Back to the dealer... leaking head gasket. The service writer confided that at this point, they recommend the top end of the engine be rebuilt as it is inherently fragile, but that the warranty company would only pay to replace the head gasket. In addition to the major problem of the engine, the digital dash would come on and off when it wanted, not necessarily while I was driving. I happily took a loss and sold it the day the warranty expired. Haven't talked to my brother since. I have owned a 1966, a 1970, and a 1971 Cadillac and all were outstandingly reliable with bullet proof engines. Alas, the 1980s were the "dark years" for General Motors. Don't get me started on the 1985 Pontiac Fiero/Fiasco.
We, the highly skilled professional Cadillac mechanics at a very renowned and extremely high volume, strictly Cadillac dealership, had a little rhyming saying about the Cadillacs in the mid 1980's (pertaining mostly to the HT4100 engine models):
Cadillac, Cadillac, ride the best. Drive a mile, walk the rest.
I tend to disagree with you. The Coupe DeVille I own has 191,600 miles on it. The jack has never been used.
Most of your comments are in regards to routine maintenance being performed on your vehicle. Starters, alternators, gaskets, seals and the like all go out on most GM vehicles between 70-80,000 miles. The timing chain and the oil pump and fuel pump go out about the same time.
Your electrical problems are a result of a faulty or abused alternator and electrical system.
You didn't say if you had a trailer hitch or pulled anything with your vehicle. Aluminum motors struggle under harsh conditions. Most people do not let their vehicle warm up before driving. This causes tranny and seal problems. Most people do not read their owners manual and find out that they can only burn/use certain motor oils. Most people do not change their own oil or properly flush their transmission or cooling system in their Caddi at regular intervals. Aluminum engines will run hot if abused or not properly maintained.
I am just now replacing all the sensors, modules, seals, fuel pump, rebuilding the alternator and starter, changing radiator and all external seals and gaskets because it needs to be done at 191,000 miles. I do the work myself because I know it is getting done right.
If you own a Caddi and take care of it, it will take care of you. Parts and labor are more expensive at dealers and service centers because it's a Cadillac. I respect my Caddi, and I get out of it what I put into it.
Yeah, the 1985-1993 Cadillacs were probably some of the worst ever made (other than the brand new ones being sold today). They were too advanced for their day and were mechanical nightmares as a result. Not only that, but the small, unreliable, and underpowered HT-4100 V8 was a joke, that was nowhere in the league of Ford's older but proven 302 CID 5.0 L V8 engine, used on their big cars at the time. Thankfully Cadillac kept the Brougham at the same time, with the proven and reliable Oldsmobile 307 V8 engine.