Radiator Cap Corrosion Problem

[Guest M R Simpers]

I have a standard (current re-production item) Model "A" Ford mono meter radiator cap assembly. It is one of the flip top twist lock types. It is fabricated of a chrome plated die-cast material. The interior flat surface under the rubber gasket is corroding into a white powdery scale. This corrosion has not got into the threads yet. A number of years ago I had one of these corrode so badly that the threads just disappeared.

I want to stop this corrosion. I have scraped off most of the white powdery scale, but I could probably do a little better.

Is there any way to coat and protect these rough scaly areas? I'd rather defer to some "good advice" in lieu of just "slopping on some paint".

Any comments?

Thanks

M.R.

Cocoa, Florida

[nickelroadster]

In situations like this I have used a two part epoxy product that is designed to repair things like sinks or bathtubs. It is a little thicker than ordinary paint and if the surface is prepared well, you can get very good adhesion. Make sure you are not applying it over corrosion. Sandblast or at least wire brush very well before application. I have an aluminum water pump that was getting galvanic corrosion that I applied all over the inside surfaces and it has worked very well for five years, even filling substantial pits.

[Guest M R Simpers]

Good idea. My only concern is being able to neatly spread the epoxy material down in the threaded neck hole on the flat ringed flange (the corroded surface). There will be no easy way to sand the epoxy flush without making some sort of round sanding block, which can be done of course. This is the surface the bears against the thick rubber gasket. I won't have to be as concerned about other side of the interior round neck flange (that's up towards the meter) since it doesn't have to be a flat surface.

As for cleaning the surface, I think I can get it cleaned. There are still high spots with the original chrome showing.

Thanks...

M.R.

[Rusty_OToole]

About getting a flat gasket surface. What if you prepared a flat surface covered with plastic, like a plastic grocery bag, and set the cap on it when the paint was wet? I have done this with plastics and epoxy. When it was hard, the plastic peeled right off leaving a smooth shiny surface.

You might try a dab of the epoxy to make sure it will not stick to plastic bags, or wax paper might work better. I have used both.