We are looking to purchase a first classic car to finish restoring (1955 Oldsmobile 88). Day before ready to make offer, we noticed rust under the headliner, at least around the edges. We can't of course, see all the way under the headliner. Seems to be some chunks of rust, even. Car seems very solid on outside. But, we are now worried about integrity of roof. Should we be concerned, suggestions on what to look for specifically when we go look again, or is this a common problem not to be concerned with?

 

If there were "chunks" of rust under the headliner then you would be able to see the rust from the top side of the roof. Could you be mistaking a deteriorated cardboard lining for rust?

The major areas of concern for rust are the fenders / wheel wells and the rear window. Good luck.

 

In my 53, the roof is insulated with a brown material that had deteriorated badly, causing some staining in what little was left of the cloth headliner. The roof itself was quite solid. The undercoating (primer) was also brown. I'd say if there is no visible external signs of leakage, it's more likely that the insulating material is causing the staining/chunks.

 

It's a lot of work but you might remove the headliner so you can do a better inspection. The rust spots you could then clean it off and prime it with epoxy primer and touch up the paint. The epoxy primer would stop the rust.