E9 Coupe Rust Diagrams

Floor Pans

Inspecting the floor pans can sometimes be a little challenging. From the inside you have to pull the carpeting and padding back first, then the sound proofing material is exposed. The material is bonded on to the floor pans and is not easily removed. The only way to check for rust problems in this area (if the car you're inspecting isn't yours!) is around the outside near the edges. Around the base of the pedals is a common area for problems, and just about every other area where water collects. Inspecting from the underside of the car can be tricky too. Unless the car has had some work done to it in the past, it will have an undercoating on the entire underside of the pan. This undercoating can help protect against rust, but it can also help hide it.

Rust problems in floor pans can be attributed to several causes. Any rubber seal that keeps the elements out of the passenger compartment can be suspect for a path for water to enter the car. Since the floor pans are the lowest point, any water will collect there. A leaky windshield gasket is probably the most common cause, but water could also be entering through the underside of the pedal assembly and the underside of the floor pans themselves. Each of the four floor pans has a large circular "drain plug" that can allow water and moisture in from the bottom if not properly sealed.