Welding Dirty Metal

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I need to weld up some parts on the Howard DGA-15P and was wondering what others are using to clean 3ST (3003) that's been in an engine compartment of a round motor for 56 years and impregnated with oil. The parts I need to weld are for the intake. Last year I welded up the blast tube on the right side, now the left side is broken in the same place. My oil cooler scoop had been patched so many times, I built a new one last year.

The other part I need to fix is where the two blast tubes come together prior to the carb air box. It looks like a small viking helmet. The base where it mounts to the carb air box is worn away to the point that what was left cracked off. The piece was just laying on top of the airbox. I'm lucky pieces didn't get swallowed up by the engine through the carb. I plan on cutting it off above where it is worn, rolling a new piece and then welding it on. In the past, every time I go to weld the old 3ST, there is so much oil and other impurities that I have trouble getting the old material to puddle before vaporizing the new.

I've tried lots of different methods of cleaning but still cant run a decent bead! I end up with very ugly welds and lots of material that has to be ground off to get it so it at least looks acceptable. Needless to say, my Al welding skills aren't the greatest. I've been using TIG so far but after reading your web site, may decide to try the gas route. Thanks for the help. David

The Tin Man Respondeth:

I would try a gentle preheat and scrub with 70% denatured alcohol and a stlss toothbrush. Both sides. Weld when preheat stays clean.

Kent White

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