Hi I have a 71 cutlass 4dr with some rust issues around the back window. The back has rusted to the point that there is a leak in the lower left hand corner of the rear windshield. From the outside it looks like there is surface rust only but when the trunk is opened there is a quarter sized hole directly under where the leak is. As a result the trunk fills with water after rainfall. Most likely the rear deck will have to be replaced in the future but for right now my main goal is trying to save the trunk as a whole. The trunk floor is in pretty good condition with only surface rust that could be sanded down. What would be the best quick fix/protection plan until I can really get in there and work? I was looking at Dupli-Color rust fix. It sounds like you can just spray over the light rust and it will prevent anymore from developing as well stop what is already there. I was also looking at Rust Bullet. Has anyone had any success with either one of these or anything else?
Rust Bullet
http://store.summitracing.com/partde...5&autoview=sku
Dupli-Color Rust Fix
http://store.summitracing.com/partde...0&autoview=sku

 

After stopping the rust with whatever method you use, Perhaps you could use some epoxy to fill the hole from the outside. Is the hole in the window channel or on the exterior surface of the C pillar/quarter panel? If in the channel, wire wheel the metal till it is bare and mix up some epoxy, tape the hole from underneath so it won't drip through and pour epoxy in the channel right before it begins to thicken up. If on the exterior flat surface you my have to have it braised or have a plug welded on.

 

The only real solution is to cut out the rust and weld in new metal. This pinchweld rust is very common on A-body cars, due to debris getting caught under the stainless trim and retaining water. There is no long-term fix with paint-on coatings.