Updated: Jan 7
By Norman Nock, British Car Specialists
These have plagued all automobiles since the beginning. All cars have their own little pockets that gather road dirt and this includes the Austin-Healey.
The common body rust areas that can be readily seen are the rear of the front fenders (Photo 1), rocker panels, and the front of the rear fenders. Areas that have ice and snow are more of a problem. The snow can pack under the headlamps and rust the fender to the point that the headlight will fall out of the fender.
The pocket that gathers road dirt (and road salt) in the real of the front fender is filled by the roadwheel throwing the dirt back onto the fender shield. Between the shield and the fender there is a gap of about 1/2 inch as clearly shown in Photo 2. If you place a bright light under the hood and shine it into the rear of the fender, then look into this small 1/2-inch gap. Don't be surprised at the road dirt you will see.
The result of this dirt and the moisture it has absorbed is shown in Photo 3. The triangular rust pattern on the outside of the fender shows how the dirt has piled up to the rear.
This dirt can easily be removed with a strong water jet run into the inside of the fender to blast it out. There should be a 5/8-inch drain hole in the rear of the front fender. This will allow the water to run out, but it is veryeasily plugged with road dirt.
Dissimilar metals couple corrosion and it is found on all big Healeys where the aluminium (British spelling) shroud meets the steel fenders. Two dissimilar metals in the presence of small amounts of moisture form a small battery or corrosion cell (galvanic effect) with the less positive metal corroding at the exposed interface. In this case, the aluminium will corrode.
Again, this is only found in the presence of water vapor and contaminants.
The joint between the rear of the rear fender to the aluminium shroud is the usual place of dissimilar metal corrosion. It looks like rats have been eating the lip of the shroud that joins the fender. Even when you replace a fender it is not possible to stop this galvanic action.
The only thing you can do is, slow it down by being sure metal surfaces are clean, down to bare metal as in sand blasting, prime the areas, and then under seal. Bolting and threaded fasteners pose a special problem, because of their built-in crevices. Always use new galvanized, cadmium plated, or hot-dipped aluminium coated bolts, nuts, and washers.
The most important part is to keep the area dry and clean.
The abrasive materials (sand, glass beads, cut wire, shot, various oxides, or carbides) impinge against the surface, removing both the surface contamination and making a pattern of indentations consisting of peaks and valleys that serve as a mechanical assist to the chemical bonding forces of materials applied to the surface. More information can be obtained from the book, "Corrosion Basics," published by National Association of Corrosion engineers, 1440 South Creek Drive, Houston, TX, 77084.
To prevent rust on the inside of the chassis, contact a boat repair company about foaming the inside to keep dampness out or you can spray the inside of the rails with Waxoyl, and English product that is available in the U.S.
If you have had your frame sandblasted, the primer has to be sprayed on immediately.
Following application of the primer you should consider undersealing all under body parts to help stop rust formation and to have a nice quiet body.
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