I have a friend with a cast Al valve cover that is cracked. We are having a hard time finding someone with the knowledge to weld this. I know it's done on motorcycle cases. How is it cleaned so that there is no oil trying to get in the weld? What is the best process, tig?
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Cleaning and welding cracked oily cast aluminum
- Thread starter LEEQ
- Start date
- Joined
- Nov 26, 2012
- Messages
- 1,307
Just did one a short time ago. The whole bolt area was broken out.
A wash tank is nice but not nessasary.
Clean with brake cleaner or laqure thinner.
Welding shops have a brush on cleaner that works well also but isn't a nessesity.
A stainlesss steel wire brush is nice to do final clean with.
Weld with 5356 rod with a tig with pure argon and a green tungsten(one for al).
Depending on the quality of the valve cover you will get varying results. Some are poor quality aluminum.
A wash tank is nice but not nessasary.
Clean with brake cleaner or laqure thinner.
Welding shops have a brush on cleaner that works well also but isn't a nessesity.
A stainlesss steel wire brush is nice to do final clean with.
Weld with 5356 rod with a tig with pure argon and a green tungsten(one for al).
Depending on the quality of the valve cover you will get varying results. Some are poor quality aluminum.
- Joined
- Sep 24, 2010
- Messages
- 3,096
Clean, clean, clean, and clean some more. Use hot steam or boiling water and a degreaser/ Once you get the item clean, bake it in the oven on low for a while to draw the remaining oil from inside the crack, Clean it some more. Use a dedicated aluminum only wheel to groove the crack, and use a dedicated stainless steel brush to clean the grooved out area. Tig weld the crack in multiple small passes with carefull grinding between each pass. This will eventually get you clean solid base metal that will form a leakproof weld. Cleaning is a major issue because the oil will continue to contaminate the site multiple times. Brake or motor cleaner releases a toxic vapor, so be extremely carefull if you use those products to avoid breathing any of the cloud that will come offf of the part. I generally do NOT use those chems, Dawn dishwashing dtetrgent and elbow grease works just as well. Hope this helps, If you need procedure settings PM me and I will be glad to help you set it up.
Bob
Bob
I did not know that. I've welded cast iron which is sometimes said undoable. I had access to two old timers. One with the knowledge, and one with infinite dc setting. It almost welded itself. I loved that welder and respected the other welder. I guess that Al is different. If we can't get it to tig after cleaning, what about brazing? That would be water tight wouldn't it? It's not a high pressure application.
- Joined
- Dec 22, 2012
- Messages
- 328
Bernard is absolutely correct. The deadly gas produced by heating brake cleaner is phosgene.
Tom
- Joined
- Nov 16, 2012
- Messages
- 5,596
A guy asked me to fix a cracked alternator bracket. He snapped the bolt hole ear off of it. It was very porous. I've TIG'd all kinds of AL and plenty of it but whatever this was, it wouldn't weld right. The area near the weld would just start to cave in so the natural tendency is to throw a little more filler at it where it caved in -and then the area next to that would cave in etc... I ended-up trying several frequencies, high frequency pulse, etc... I stuck it back together but it wasn't worth the trouble. As far as I know, it's still holding up but, I had to be honest with the guy and tell him I wasn't confident in it.
Ray
Ray
perhaps not just aluminum, but an aluminum pot metal. Maybe porosity like it was full of air. I would love to know how to assess it for weldability before welding. This is off of an old cat diesel, so I would hope it's good metal.