7. The car had several other smaller rust areas, some of which exhibited only minor pinholing through the surface. These pinholed areas will blow out paint or filler in a short time, so dont be tempted to just cover them up with body filler. Here, the rusted corner of the quarter ahead of the rear wheel was cut out and replaced with a patch. To prevent future corrosion, thoroughly clean the rust area while its accessible, and coat the backside of the repair sections with weld-thru primer.