TIG welding cast aluminum

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Hi guys,I'm a hobby welder with a lot of MIG experience, and a little bit of TIG experience.  On my Harley, the front motor mount on the case has a couple small (1" long) cracks on the bottom of the case.  I was wondering, how hard is it to weld cast aluminum and can the welding be done with the motor still in the bike?
Reply:To be done properly the engine should be removed.  Someone with good skills could make a decent repair in frame but quality will suffer. I've fixed my share of Harley engine case mishaps,the aluminum is usually of good quality. Where are you located?  If near Chattanooga, TN give me a shout.
Reply:Dang, I wish I was near TN.  I'm in Dallas, TX
Reply:The good thing is that the bolt goes all the way through the front of the engine case, so I'm not overly worried about it splitting out again due to stress.  Not really sure what caused it, but it kind of looks like it either got hit by something or the bolt was wrenched too tight.
Reply:What about aluminum brazing rods, just to keep the crack from spreading?  Any thoughts?
Reply:If you are not very familiar with tig welding alum, don't use this as something to learn on. There's a high chance you'll just make a mess of it. Alum doesn't weld like steel and it takes quite a bit of practice for most people to pick up the knack of it..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by crumrwWhat about aluminum brazing rods, just to keep the crack from spreading?  Any thoughts?
Reply:Originally Posted by shovelonOh, Dear Lord no!!!
Reply:Originally Posted by crumrwLol, I had a feeling that would be the response I would get.  I've used the brazing rod for repairing an aluminum boat and a large aluminum crawfish boil pot with no problems, so I thought I'd ask.Anybody have any contacts for a quality cast aluminum welder in the Dallas area?  Sounds like it wouldn't be a good idea for me to give this a shot myself.
Reply:Hello crumrw, a number of folks have given you a lot of very saavy and good information to cover your question and proposed repair. I might throw a couple of pictures on here to show you a similar type of repair that I did for our diesel shop. I used a stainless steel bolt as a "form" to help with the repair and maintain the integrity of the hole. Aluminum will not stick to stainless steel and makes it ideal for something like this. So for what it is worth here are the photos. Good luck and best regards, Allanaevald
Reply:Allan, I have to ask.  Did that bolt still have threads on it when you did that, or did you cut the threaded part off first, and just use the shank as the "form"?I would imagine that with a bolt with rolled threads, it might end up captive after that.As usual though, I always enjoy seeing your handiwork.
Reply:rlitman, actually, it did still have the threads on it at the far end but since the straight shank portion of the bolt was subjected to direct contact with the weld metal it did not "capture" the bolt in any way and it actually slid out of the hole fairly easily. Thanks for asking and best regards, Allanaevald
Reply:Originally Posted by crumrwwhat about aluminum brazing rods, just to keep the crack from spreading?  Any thoughts?
Reply:Slick repair Aevald.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Thanks for all of the info guys.  I appreciate the help. Aevald, that repair looks great!   That's the kind of quality I'm after,  and although i have tig welded aluminum before,  I don't know that I could achieve that just yet.
Reply:Hello again crumrw, if you go about the repair in a similar fashion as I did in my pics. I would suggest removal of the engine from the bike and dissassembly before making the repair. There will be a lot of heat involved and it migrates through the aluminum very readily and rapidly. Thus, seals and other heat-sensitive components could be easily damaged. You don't really want to go half-way with the repair so doing it right the first time will save you a lot of grief. Good luck and best regards, Allanaevald
Reply:Do you wheelie your bike?  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Originally Posted by B_CDo you wheelie your bike?
Reply:Then I would go with the bolt was over tightened. something split it, either stress from slamming down from a wheelie or over tightened....Is that an insert Im seeing in the case? where the bolt runs through?Or a washer  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:It's an insert.
Reply:So pretty thin around it, hmmmmmm thats going to be a tough one with I assume rubber in the middle, or is the insert a rubber mount?  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:It almost looks like the installation of the insert cracked the case?If that insert is just aluminum tube and no rubber I would die grind into the tube and weld it Last edited by B_C; 09-30-2013 at 12:14 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Insert is steel.  It slides in and out fairly freely.  Had it welded and it turned out great.  Hopefully it doesn't crack again.
Reply:Lee Zundel with Z-fab did the work.  He was very thorough and I would highly recommend him to anyone.
Reply:yeah looks like that will work.....I wonder why there was those inserts? Next time around because it will crack again....make up some aluminum spacers and die grind into them like I said and weld that up ......Im afraid that thin wall will crack again with the loose fitting steel spacersLast edited by B_C; 09-30-2013 at 10:17 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig RockLee clamped the cracks as close to closed as possible.  Those inserts are there to spread out pressure from tightening that motor mount bolt as to NOT cause a crack.  With the cracks clamped, that insert fits in pretty tight.
Reply:Hope it works for you  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Me too, thanks for all the tips guys.  Hopefully I'll be able to hone my skills to be capable of doing such repairs myself.  In fact,  I have a cracked motor case from another motorcycle to practice on, so it might be a good opportunity for me.