Crack in aluminum t-case

[Ghostman]

So I while swapping front case halves on my transfer case I notice that the used front half I bought has a decent crack down it on the bottom. So I wire wheeled it down, cleaned with aluminum, preheated with propane, and attempted to weld it up with my Miller Diversion 165.

I guess I did ok, as long as it doesn't leak and the crack doesn't spread. I welded the inside and outside, but couldn't get my torch down in one part on the inside. I think tomorrow I may grind it back down some and try to put a better weld on it.

My puddle kept getting that leathery skin look to the top of it and lots of black residue in the weld. I'm guessing that's contamination?









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[welderj]

Not uncommon to have contamination with this type repair. The aluminum can be contaminated all the way through. It helps to spend some time cooking it out and wire brushing it clean before you weld. Other than that you may be a bit cold with your weld yet.

[Ghostman]

Not uncommon to have contamination with this type repair. The aluminum can be contaminated all the way through. It helps to spend some time cooking it out and wire brushing it clean before you weld. Other than that you may be a bit cold with your weld yet.

That's kind of what I was thinking.

Would it be a good idea to grin the weld back down and weld again until all the contamination is pretty much gone?


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[onealwelding]

It would not have hurt to V it out with a die grinder either. The shop I worked for years ago did allot of work for a transmission shop. Got tired of welding cases

[welderj]

You may not get rid of it all. When I did this type job I cooked it with my tig til I got a decent weld then checked for leaks. If there were no leaks I didn't worry about the contamination. A lot of those housings were cast with sand or other fillers so there is often some junk in the welds you can't get out. I don't really like your weld so I would do something with it, just don't expect perfection.

[Ghostman]

Ok I'll at least grind it down and try again to hope it gets somewhat better. Thanks for input.


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[KD Welding]

what truck is it out of. you sure its aluminum.

[Gamble]

Really not too bad for your machine considering you can't adjust the cleaning on it.
One thing I learned when doing cast aluminum is to let it cool inbetween passes. Or it gets too "gooey" and sinks then you are really screwed.

[Ghostman]

Yes it is aluminum. NV271D front case half from a dodge cummins. I'll try letting it cool tomorrow between passes also.


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[KD Welding]

If I have to do a fairly speedy fix I start with wire brush ss of coarse. Brush -map gas torch, or strait acetelyne- acetone repeat till no more soot. I than let cool a little and then run tig over surface to be welded brushing away soot as it show till wherever the torch goes there is a shinny puddle by that time I let it cool a little than weld it out generally it goes pretty smooth from there. oh and if possible drill the ends of the crack

[Drf255]

Yes it is aluminum. NV271D front case half from a dodge cummins. I'll try letting it cool tomorrow between passes also.


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IDK how much you should let it cool in your case. You're machine is a bit underpowered already for the type of repair you're doing. Keeping the casting hot is likely your friend in this case. Especially with the size of the piece.

I've found out in short order that castings just don't weld so beautifully. You can get good on regular aluminum and then everything appears Zen with your setup. Then a series of WTFs occur.

[Ghostman]

Well ground it all down and tried again. Te outside was a bear, but I think it's good enough. But then I noticed my ground cable started smoking and melting at the clamp so I guess I need a new cable clamp now.






Looks like dog doodoo as Jody would say but it'll have to work, I hope atleast.

I also noticed that I think I want a water cooled torch even for this machine. Just doing these little welds off and on it starts getting pretty hot.


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[markfuga]

Suggestion: Cover your outside weld with JB Weld to fill any porosity that may leak. Your weld is fine to fix the crack and ensure it doesn't spread and the JB weld is the insurance that it doesn't leak.

[welderj]

Suggestion: Cover your outside weld with JB Weld to fill any porosity that may leak. Your weld is fine to fix the crack and ensure it doesn't spread and the JB weld is the insurance that it doesn't leak.

If you put jb on it a y future work will be 100 times harder to do. That should only be a choice of last resort. Nothing worse than trying to weld aluminum that has had jb put on it. Btdt many times.

[HT2-4956]

If you put jb on it a y future work will be 100 times harder to do. That should only be a choice of last resort. Nothing worse than trying to weld aluminum that has had jb put on it. Btdt many times.

Yeah I've been down that road myself a few times where some ones made a prior attempt to fix some thing with JB weld. About the only thing you can do is take a die grinder and make sure you've got every little bit of it removed before you even think about starting to weld. Other wise you're in for one hell of a tuff go at ever getting any decent beads put on something.

[Ghostman]

Thanks for all the input and help guys!


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[HT2-4956]

Ghostman,

Welcome to the wonderful (and oft times aggravating) world of Aluminum casting repair. Some times what it most requires is just a dogged determination to stay after it until it starts welding good. Many is the time I've had to weld, grind out and re weld (some times multiple times) before you get enough of the contaminates out of the area to where a good, non porosity ridden bead will lay in there. In fact any more, if it's a casting that's been exposed to oil or grease in service I go into it thinking I'll probably need to grind back out (at least partially) the first bead I try and lay in.

Here's some general recommendations to help insure success ......

Degrease and clean up the whole casting (not just where you're going to be welding) as best you can. Other wise while handling the casting you just get you're gloves all greasy and then it gets on the filler rod (and everything else you touch) and in to the weld by that route. Plus then you won't have to breath all those stinking fumes while welding from that gunk burning off. The other thing a good over all clean up of the casting will do for you is allow you to inspect it a lot better for other cracks or defects that might be present other than the apparent ones that got the casting brought to you in the first place.

If the casting is really gunky letting it soak in a solvent tank (and scrubbing at it) for a while is not a bad idea. Hot pressure washing is also another good option. I've even taken larger castings to the local self (quarter feed) car wash as a way to start getting them cleaned up.

Weld prep... as with a lot of things in welding a good prep is usually the key to insuring good results. Just running a bead on the surface over a crack usually isn't going to last when the casting goes back in service. For a good repair you need to have 100% penetration. Most times what I do is grind the prep half to two thirds into the thickness and get a least one good bead in it before then back grinding a prep from the other side making sure I'm down into the weld I put in on the first side. When I've got one of those situations where it's difficult (or impossible) to get to the inside to weld I'll grind my prep almost all the way thru from the outside so that I'll be able to melt thru and insure I get full penetration that way.

When it comes to "grinding" a weld prep on aluminum....well, don't. Your best friend for making weld preps on aluminum castings is going to be an open toothed carbide burr (the ones designed for non-ferrous materials) in a die grinder. They'll leave you a nice clean cut U-groove. Abrasive rocks leave non metallic particles smeared in to the surface of the aluminum that will just work against you getting a good bead laid in. If you're already dealing with contaminants that are having a negative effect on the welding there's no sense in adding any more to the equation.

Pre-heat (especially with an under powered machine like yours) is also going to be your friend. I think you'd have gotten a lot better results if you would have gotten that casting up into the 300 to 400 degree range (and kept it there till you were done) before trying to weld on it.

[HT2-4956]

I also see where another poster asked if you were sure it was Aluminum. That's a very legitimate concern with things like this. The last transfer case I fixed (out of a Bronco IIRC) turned out to be Magnesium and not Aluminum like the customer told me.

If you ever start welding on a casting that you think is Aluminum and immediately see a green tinted halo around your arc stop welding as soon as you notice it. That green tint around your arc is a pretty fail safe indication you've got a Magnesium casting. If you go and mix a bunch of Aluminum filler rod in there you'll have to be sure and get it all ground back out before you'll ever have a chance of fixing it with Magnesium rod. Those two metals just do not play well together.

FYI, you're in for some serious sticker shock when you go to buy your first pound of Magnesium filler rod.

[DougAustinTX]

Everything HT2 said is absolutely "right on". Those are stress fractures, and a relatively cold weld laid on top of the cracks is not going to hold for long. You really need to U out the crack with the carbide bit and weld deeply into the aluminum in order to get any strength into the casting. Also, if the casting is thick enough, I usually grind the crack fairly deeply and weld it with a spool gun to speed up the process. I am usually in a hurry. : )

[Ghostman]

Well so far it's holding together ok with no other visible cracks, but it has the tiniest tiniest seepage of oil coming out somewhere. I probably have at least one or more pin holes I guess. No surprise for me since I'm really an amateur. It seems the leak is so slow though that it might take a year before it would get low on oil.

[NicheFab]

Was the nut on the lug connected to your ground clamp loose? I know ground clamps get hot under heavy welding conditions, but they get hot faster with a loose nut.

Maybe not, but just sayin..

-Niche

[Ghostman]

Yes I think it was a tad loose after it cooled and I checked it. Damage had already been done to the end of the cable though.


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