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MG MGA - Rust repair again

Hey folks, I have the right front "wing" on the work bench and I have discovered a small rust through on the bottom lip. I have applied some Eastwood "Rust Encapsulator" to the area and I will proceed to fill the area in. My question is this; Does this sort of treatment work or should I have someone "cut & weld?"
The entire area in question is about 2" square with 3 small pinholes. Thanks again, Tom
Thomas McNamara

Thomas,
Where there are small pin holes on the exterior, with larger craters on the interior, I use lead to fill the interior and this seals the pin holes. Obviously you cannot do this without damaging the paint but this eleminates cutting, welding and then straightening the panel. Hope this helps and have a good day!

John
John Progess

Tom,
If the rust has holed through then it has eaten away the metal. Unless you remove the rotten area, it is my firm belief that, no matter how it's repaired, it won't be long for the rust to reappear. My advice is to cut and weld in a new piece. If as you say it is only a 2" square area then it should be an easy enough job.

Frank
F Camilleri

Thomas, I can't say about the Eastwood product, but I've used other rust converting products containing Phosphoric Acid, which is usually the active ingredient in such products with good success in protecting agains further corrosion. As for the repair, once you have holes in the metal it's hard to get a good repair using any type of filler other than lead, brazing, or welding. Any type of fiberglass or epoxy based filler can start to loosen over time allowing moisture underneath and the corrosion will start up again in an enclosed space. Since this area is already such a vulnerable area because of splash from the front wheels I'd advise getting the panel welded if you can.
Bill Young

Success with filler depends on how thin the metal goes. When I started my first restoration in 1977 all fenders on my car had outer pin holes in the bottom 5-inches or so with small craters on the inside, but at least 90% of the area was still very close to original thickness. The corrosion was limited to small craters only, up to the point where they break through the outside with a pin hole and cause blistering of the paint.

In my case I had the entire car body stripped to bare metal by RediStrip chemical and electrical process, so the metal was very clean (after washing). I filled the craters with Duro Plastic Aluminum, or Plastic Steel (don't recall which now). After sanding smooth both sides it was primed and painted, put back on the road in late 1986.

124,000 miles later in early 1998 I banged out a few dents and repainted the outer body with fenders removed, including inside and outside of the fenders.

Another 90,000 miles later over winter of '07-'08 I did body sill replacement and repainted the entire body inside and out while off the frame. The rear dog legs were a bit rusty and needed repair this time. The front fenders are still in tact with all original metal along the bottom, still holding the small amount of filler from the pin hole repair in 1977 (now 230,000 miles later).

If the metal is rusted thin all over it needs to be replaced. If you have only local craters in otherwise mostly full thickness sheet metal, then it can be filled and sanded flat at full thickness.
Barney Gaylord

The really important thing with filling holes like these is to make sure that moisture cannot get to the filler, which will act hydroscopically and swell, ruining your paint and causing more rust where the metal is already thin and very susceptible to more tinworm.

You will need to treat the backside of the fender with a good quality stone.chip or underbody Schutz to keep the moisture away from the filler. If you leave it bare on the backside, you will be redoing the job in a very short space of time.
dominic clancy

Thomas, when I restored my Coupe last year, I found small pinholes on the bottom parts of the rear and front fenders. I had them acid dipped and then sand blasted them to get them really clean. I paid close attention around the pinholes and made certain that all signs of corrosion had gone by carefull sand blasting. I checked with my body and paint expert and he said to use a metal based filler over the pinholes and they should be OK. I used Evercoat Metal to Metal which is applied directly to bare metal and is impervious to water. Be careful of talc based fillers that are pervious and allow moisture in. I then painted the fenders with etch primer, high build primer and finally a primer sealer. It's too early to tell if it worked but based on Barney's results it looks like it should be OK. See attached photo.

Andy



Andy Preston

Hi folks. For pinhole areas, I have found that sandblasting the rust out, and then applying short strand fiberglass filler gives a strong, waterproof and long lasting repair. Just my two cents worth, Glenn
Glenn Hedrich

This thread was discussed between 14/12/2009 and 18/12/2009

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