Floor Pan Rust Issues On 1990 - 1993 Chrysler Imperials

Imperial Home Page -> Imperials by Year -> 1990 -> Repairs & Maintenance -> Rust

The rocker panels, bottoms of doors, and the rest of the car is always subject to rust all the time. This is typically due to paint imperfections and body design and imperfections.

However rust is also sped up by road salt which coats the car with salt which will hold moisture. Later this salt and water will cause rust, but only when exposed to bare metal.

Needless to say, the best preventive measure to rust then is a perfect paint job over all metal parts exposed to water. However that can be hard to do (Demonstrated by how many people touch up their doors from parking lot dings, but not their underbody from driving on unpaved roads, etc.). Keeping the paint clean and waxed even farther helps by helping in keeping salt from sticking to the body. But it simply is not practical to jack up a car and clean the whole thing including the underbody. As a result, the floor boards are often the first thing to go. And on a uni-body like car like the Imperial, the floorboards are also quite important structure wise for the strength of the car.

So if you must drive your car all year, and you start to get rust, the best way to keep it under control is to touch up the underbody. This can be done by cutting or sanding off rust, repainting metal, and then applying a coat of rubber underbody coating over the new paint. This is the first step in keeping rust under control.

However if your car already has rusty floor boards, with holes which would scare even the flintstones, then perhaps it might be a smart idea to replace the infected rusted areas.

Here's how its done.

First, look under your car and get an idea how bad things are. If the rust has kept to the floor boards, and hasn't yet attacked the frame and other mission-critical elements, then you should save your car now while you still can. But if the frame is also being hurt by rust, you may need to start looking for a new car (unless you have the time, money, ability, and place to do a from the frame restoration). If you want to fix the rust, continue now.

Remove the seats, carpets, and bottom trim parts from the inside of the car. From here you can see the top of your rusty floor boards, and that in and of its self will show you how bad things are. If you can see the road under you, or rust everywhere, then you really needed to do this. However as a side note, looking at the top of the floor boards will show you if the rust came from inside the car or out.

Leaking weather seals, windows, or water/snow from peoples' feet will leave water inside this car. This water will soak into the carpets and then go to the lowest portion of the floor boards. This will in return, leave sitting water which will rust out the floor boards as it works its way through the paint. If the rust came from this situation, it will be evident by rust in areas on top, where it isn't below, and/or more rust on top then underneath. If this is the case, now is a good time to find and fix those leaks.

Now, using grinders, cutters, and sand paper, remove all the metal which is rusted. In the case of rust holes, as a rule, remove an extra 1-2 inches from the end of the holes to ensure that all the bad metal is removed. Then, cut out the holes so that they are set shapes (i.e. lots of holes in one areas can be cut out in one large square). Then get some scrap metal to weld in place of the holes. Some places sell replacement floor boards, but if that isn't an option, use the sheet metal from the roof of a hard top car. Roof metal is often of thicker gauge, and is already painted and primed from a car factory. The newer the roof metal the better the rust resistant paint and primer will be. Factory primer and paint has been traditionally far better at taking abuse then after market paints found in body shops and car stores. As a result, the roof material may be better at lasting. Cut the metal to fit, leaving an extra couple of inches on every side of the metal pieces. Then weld the pieces in, while taking car not to leave any holes, nor areas where water can get trapped from the under side of the floor boards. On the top of the floor boards, use a grinder or sandpaper to smooth out the new metal so it conforms with the original sections of metal still remaining.

Then paint. Get many coats of both primer and paint on both sides of the floor boards. Then apply rubber undercoating to BOTH sides (as that would help prevent scratches on the bottom, or rust from sitting water on top).

Reinstall carpets, trim, seats, and your done. If this is done as needed (with similar procedures to fenders, etc.), rust can be kept under the control and the car will last almost forever (assuming you can keep getting the A604 rebuilt or replaced...). Don't lose the war against rust! Too many of these Imperials have already been lost this way!

This page was last updated on October 2, 2003.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club