What chronic problems occur with '93 Cadillac Allante?

Northstar engine is no good when older. Convertible top is a pain in the ass to put up and down. Parts are hard to find. Electronics where ahead of their time on some things and not very good. If the ABS module goes bad its about $800-1200 to replace. I could go on for a long time. Fun good looking and driving car, just expensive to maintain.

It is probably much easier to find parts and a mechanic familiar with other older GM cars. Allante's were a limited production car - over 20 years ago. Only about 20,000 or so were built during the entire production run. That being said, they are not particularly difficult or expensive to maintain. The potential expensive part is when something goes wrong with the electronics. They were far more advanced than other cars of that time period. Only a few places have an abundant supply of parts and expertise on these cars. The two main ones are in Florida and New Jersey. Other than that, engine, brakes, etc are no more than any other car.

Cylinder head threads release after 150k miles, then head gasket blows and altogether this is not an easy fix. Time-serts and tools are pricey, engine needs to be taken out for this. Another thing is the gearbox: Other Cadillac transmissions won't fit. That means expensive rebuilds instead of cheap replacement.

1993 convertable top wont lock down in the back. what's the problem ?