Need help with a cast aluminum repair....

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Alright, I have never had much luck with cast aluminum. I am pretty decent with the tig, steel and billet aluminum. I have very rarely touched anything cast aluminum but it has always been a nightmare for me .I had an ear that was cracked on my transmission.. I V'd out the crack and tried to weld it up. Weld under the hood looked a little dirty as I was going no matter how much I cleaned it... I then went to flap disc it a little and put some more filler on it and the weld flew off . I was like what the ****!! Didnt stick at all. I tried heating it with a mapp gas torch, and weld it again. I hear it cracking after I am done, then I gave it a few whacks with a hammer and chisel and this one cracked the weld in half and just chunked off... Hard to see in this pic, but I V'd it out about .200" deep. EDIT: The pic almost makes it look like it is magnesium. It is notHTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:4043 filler is what I used.HTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:Myself I use 5356 but that's neither here nor there...You say it's cracked... Not broken off?Grind the crack out from both sides until you meet in the middle and crank up the heat...Get a puddle to form on either side and pump in the filler...do both sides...Let cool a little bit and regrind it to halfway thru and weld it again...Sometimes it takes 3..4...5 times for it to work but it will.Give it time....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Thanks Zap.. It is just cracked, not broken no. When I bought it a long time ago it had epoxy on the ear but I could see it wasnt cracked too bad and not all the way through. I ran it in my car for a while and had no issues... Got a newer trans so I was going to sell this one but the guy didnt like the epoxy. I told him I would fix it, and he would buy it.I think I wasnt hot enough... I tried to do a few passes to get some "cleaning" going... Then I tried to lay in that bead and it just cracked off. I was like what the hell!!Ill give it another go tomorrow night, probly try and preheat it a lot hotter. Damn thing sucks up so much heat thoughHTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:For cast aluminum I always used 4043 until 4943 came out last year......I don't even buy 4043 anymore. The filler works really good,we talked about it before and how well it wets out.  I typically assume cast aluminum is going to be dirty inside (Dirty sand or whatever they use during the pour)  and dial down on the balance, maybe 69 -  70  weld joint prep is everything with cast.  I have good success with 3/32 and # 7 std cup you can throw some helium in the mix if you have the capabilities but it's not necessary....Run 12-15 CFH with an inverter machine I really like 2% Lanthinated  (Blue)  And weld it up..  http://im1.shutterfly.com/media/47b8...?tn=-548172496Last edited by B_C; 03-11-2015 at 08:38 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:The tranny case may be too high in magnesium for aluminum filler rod to be used. Just a thought. Are you sure it's cast aluminum. Try magnesium filler rod.  Google welding magnesium and how to test wether it's aluminum or magnesium. Welding magnesium with aluminum filler does exactly what you described
Reply:I also use 4943 filler on cast aluminum. I've had cracking issues with some boat drive parts in the past, as mentioned before, just grind out and give another go at it. I've never had one that wouldn't finally take.Good luck!-DoogieMiller 350PMiller Trailblazer 325 EFI w/ Excel PowerLincoln LN25 suitcase welderXMT 304/22a feederMiller Syncrowave 350LXMiller EconotigHobart Handler 140(2) Uni-Hydro 42-14Hypertherm 65 plasmaWEBB Gap bed lathe
Reply:Well the idiot award definitely goes to me... I tried checking the filings with a lighter the other day and it didnt seem to be mag.. Well I gathered my shavings and hit them with the mapp gas torch and it was 4th of july sparklers.... So I guess now I just need to get a magnesium filler rod and try again?? HTP Invertig 201Lincoln Idealarc SP250Miller 180 AC StickBy farmall:They should have held the seagull closer to the work, squeezing evenly for best deposition.
Reply:There is a test you can do with common white vinager to determine if it is high in magnesium content. Check google
Reply:Originally Posted by fordmanWell..So I guess now I just need to get a magnesium filler rod and try again??
Reply:look for a MG cast in the metal somewhereWelding/Fab Pics: www.UtahWeld.com
Reply:Originally Posted by dave powelsonFor future reference, what is this transmission-to?Some stuff isn't straight mag, but an alloy mix--which may preclude the use of plain mag rod.Price some mag rod and roll eyes some more.I've only done a tad of mag welding--but it reacts more like pot metal, fighting oxidation and is a beetch.
Reply:I can tell by looking at it that it is magnesium.Where is Prundale anyway?Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:this is probably your best bet for mixed metal composition your not sure of....5 - 18" Aluminum Repair Rod HTS-2000Brazing / Soldering / Low Temperature / No WeldingOrder comes only with~ 5- 18" HTS-2000 Brazing Rods with Printed Instructions, you will need a tinting brush to use I sell full kits in my Ebay store see my other listings please!(The best size to work with is 18" -manufactered size) ~not cut smaller as some have tried to sell...    Requires No Flux. Metal-to-Metal Bond.    Stronger than the Base Metal - up to 45,900 PSI.    Use Any Heat Source, such as propane, butane, mapp, or an oxy-acetylene torch.    Low Temperature. Between 717 and 737 Degrees Working Temperature.    Over 500 Degrees Below Melt Point of Aluminum.    Brazes all Aluminum Alloys, including zinc, magnesium, pot metal, and cast.    Stores Indefinitely.    "Second Generation" fluxless low-heat brazing rod for nonferrous metals.    Joins all aluminum alloys, including those that are not easily joined by high-temperature brazing.    WHY HTS-2000: Superior to all other aluminum brazing rods on the market! Longtivity and strength makes this the very best~ number 1 of any brazing rod!!!!!!!!!!!!!     FREE Tech help if need!    YOU WILL NEED A TINTING BRUSH TO USE...not with order.We will combine shipping based on weight.We Accept Paypal: Paypal Accepts MasterCard, Visa, American Express, Discover, and Electronic Check.Thank you!Of all the things I lost I miss my mind the most...I know just enough about everything to be dangerous......You cant cure stupid..only kill it...
Reply:Try some AZ92A  tig rod...... Should do the trick! Makes sure you grind out all the aluminum you put in there