I have developed a leak in the gas tank of my 1971 2800, evidently in the seam. Are any of the sealing liquids I read about in the Roundel, like 3M Scotchclad #776, worth the effort? What is the required preparation?
Author: W. F. Gorenflo
Lakeside Park, KY
Antique car publications have scads of ads for these products. They are a temporary solution, since the vibration and shock the fuel tank in a car experiences is much beyond that of a stationary tank, for which most of these coatings were designed.
Preparation involves draining the tank, removing it (no problem) drying it, usually rinsing the inside with acetic acid (vinegar) allowing to dry, pouring in the glop, slopping it around for a while, waiting a couple of days for it to dry, and then reinstalling the tank.
A member down in East Awfulgosh, Massachusetts recently installed a new tank in a 1970 2002. He thought it quite an easy task and preferable to the steps outlined above, even in light of the just over $100 price tag on the tank.
Note that OEM BMW gas tanks do not have a drain plug any more and are not made with an indentation at the top of the tank in which to run the wires to the sending unit of the gas gauge. They are, however, completely coated with a-rubberized compound that looks to be nearly indestructible. Tech Ed