How to Repair BMW Fuel Tank (1600 and 2002)

As many 1600/2002 owners know, gas tanks have a tendency to rust at the mounting flange, creating annoying and dangerous leaks. A relatively simple and inexpensive cure exists which should last forever… almost.

The tools and materials required are:

1. Assorted metric wrenches, and common tools

2. A hand drill with wire brush (sandblaster is preferable)

3. Strip of 2-color epoxy ribbon

4. Epoxy fiberglass repair kit (Duro E-Pox-E kit available at most discount-type stores for $2)

5. Epoxy thinner (Sears)

6. Duro ‘Liquid Steel’ or equivalent (discount store).


7. Rust-preventive metal primer

8. Butyl rubber caulk & gun.

Start the project at the beginning of a 2-day period when the car won’t be needed. Make sure tank is almost empty and drain the remainder. A 2-1/2 gallon metal tank fits nicely under the drain plug. Remove the gas gauge by crossing two screwdrivers engaged in opposite gauge flange slots, rotating counterclockwise. Remove the filler neck boot, then the tank flange bolts. Remove the tank. Keep the original floor seal only if you want the flange to continue rusting! This foam allows water to be trapped under the flange and is probably the cause of the rust in the first place.

Air the tank thoroughly, then tape the openings and wire-brush or sandblast the flange. It may be necessary to do only the bottom side. Look for pinholes just toward the inside of the seam weld, which should become visible as the flange is cleaned. Using the ribbon epoxy, fill all pinholes by rubbing epoxy in with a hammer head. (A piece of polyethylene vinyl will keep epoxy from sticking to the hammer.) Cover the rest of the flange with the Liquid Steel.

Now for the real fix. Mix the two-part liquid epoxy thoroughly, thinning only enough so it flows well. It might be advisable to use a bit more hardener th n normal because of the thinner. I didn’t and it took the epoxy 36 hours to cure! Pour the resin into the tank opening nearest any pinholes, holding the tank almost vertical to contain the resin to the flange seam. Rotate the tank so the epoxy flows along the seam. Do this every fifteen minutes or so until the resin begins to set. Put the tank aside in a warm area to facilitate curing.

While the tank is curing, clean the tank floor cutout with the wire brush. Paint this area and the tank flange with rust-preventive primer. Just before replacing the tank, lay a thick bead of butyl rubber caulk around the edge of the cutout; when the tank is installed this will seal the area from further water penetration. Be certain to blow-dry or rinse the tank with gasoline; install in the reverse order.

The real question is, “Will it last?” Epoxy is resistant to gasoline and bonds well to steel, so if the leaks are stopped, it should last. If the added step of butyl caulk is taken, the cause of the problem should definitely be eliminated. Beware: do not use the more common polyester resin! It is not as resistant to gasoline and bonds poorly to almost anything but glass. In any event, success is quickly determined when you refill the tank!

Author: P.R. Reitz


Submit a Comment

Your email address will not be published. Required fields are marked *

Restoration Categories

Updates by Email

BMW 2002 T-shirts

Today’s BMW Poll