BMW E30 rust spots and body repair
Where does the E30 rust most commonly?
Typical places are the corners of the front footwells, the round service hatches in the footwells, the rear wheel housing around the fuel filler and vent, the battery tray, the wheel arches of the fenders, the bottom edges of the doors and the corners of the boot. A large and demanding spot is the cross member between the rear spring plates.
How is a rust spot repaired so that it lasts?
Sanding and spraying alone is not enough. The rust craters are blasted with sand, or the area is replaced with new sheet metal. Then come acid or zinc primer, body filler, paintable sealer and paint. The filler must go on clean or roughened metal, not on top of primer.
How are seams and rust protection handled after the repair?
Sand the seams smooth and paint them right away, because a bare seam rusts quickly. Acid paint works as a rust-proofing primer, with topcoat over it. The seams are finally sealed with body sealer. Rust-proofing oil is sprayed into the sills from the inside.
How do I find out the extent of rust damage on the underbody?
Take up the floor carpet and examine the floor, because thick sealer can hide thinned or completely missing metal. More to repair is often found in the floor, wheel arches and sills, so it is best to repair the whole floor at once.