Aluminum brazing/welding

Had a constant oil leak from the right side case (clutch cover & filter housing). I did not want a JB Weld or RTV temp fix. I removed it, wash it, opened the gap a bit, drilled holes at each end of the crack, cleaned with a wire brush and used Harbor Freight aluminum welding rods. Sat it on some bricks, used a simple MAPP gas torch, gave the general area a good warm up and then concentrated the heat in one area for about two minutes. Then touched the cracked area with the rod, and it flowed like solder. Dressed the welded aread with a Dremel tool sanding drum, leak tested it. 100% leak free. Will paint it this weekend. I would consider this brazing or silver soldering since the base metal does not melt, only the rod. Look at the picture.

crack welded.JPG

I tried some aluminium welding rods and they didnt work - was using a butane torch - is that hot enough ?

39 minutes ago, S.O.A.N.Z said:

I tried some aluminium welding rods and they didnt work - was using a butane torch - is that hot enough ?

No, the butane torch does not get hot enough. Aluminum dissipates heat very rapidly, so do not set the work piece onto steel. I used brick to rest my side cover upon. Use the rod's from Harbor Freight, as they have a higher zinc content, so they melt lower, about 750 degrees. Use a propane or MAPP gas torch, and start by heating a circular pattern around the repair area for three or four minutes to get the aluminum uniformly hot. Then find a spot in the middle just below the repair area and concentrate the blue tip of the torch there for about two minutes to get that area about the 750 degree mark. Then while keeping the heat on, touch the rod to the center or the repair area and watch the rod melt and flow. Practice with a few scrape pieces of aluminum plate or flat bar, until you get the technique. It will work, it's just about getting the heat concentrated in that one area long enough to melt the filler rod.

Edited by HomerDodd

yeah i had a feeling it was heat issue - have to invest in a hotter torch then

This is a skill I need to learn.

There are several good video's on You Tube. Here are a few better one's that I liked:


As soon as that gets cooled suddenly while it's hot, such as riding through a puddle, the braze with break. Your best bet is to pull the cover off and have it tig welded.

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The aluminum brazing rods are legit for uses like that. There are many engine cases running around with patches like that.

Maybe not so good for structural frame repairs but even TIG welding isn't unless heat treated afterwards.

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