[Charlieman22]

Hi all - hobbiest welder.
Working on cast aluminum 2 stroke cases.
Could use some advice on specific challenge.

My set up:
Primeweld 220 Tig.
Air cooled.
3/32 tungsten - balled end
4043 and 4049 1/16 filler rod
Furick 10 cup

The issue - I've managed to get decent results - but one thing I can't seem to get rid of are some porosity holes.
The weld puddle just goes around them like a donut.
I have tried to drill/grind them generously - but every time I go back over it - same results.
Picture below of example.
Would welcome some insights on how to address these if anyone has some to share.
Many thanks!
-CM

[tweake]

the thing i try to do with contaminated aluminium is to cook the the crap out as much as possible first. do a no filler run first to help clean it.
then weld a thin layer over the top. if any crap or porosity shows then grind that out. layer again.
the idea here to put down a clean layer so you can build up off that.

for gear, you don't need a 10 cup. a 5 or 6 is perfectly fine if not better, you get more heat out of it with the small cups.
a 3/32 sized filler is probably better unless your doing really thin stuff. bigger filler to cool the puddle down quicker.

[BillE.Dee]

tweake is right. try running a bead without filler to get the crap cooked out. You will clean the hell out of it, go to weld it and from absolutely no where ..... crap comes up thru the weld.
I just did a oil cooler, I cleaned the sunovagun for ever, THOUGHT I had it clean, ran a pre filler pass, showed nothing, began welding and presto change O,,,,,CRAP comes to the surface. Those darned hydro carbons are absorbed by the aluminum and you can only chase them around until you get what you're lookin for.
Good luck and be patient,,,a little at a time. My project made me drink BEER. I'll be forever indebted..

[Charlieman22]

Thanks gents.
Tips are helpful.
Will employ a few of them - including the beer part (seems crucial)- and see if it helps.
I may try and drill out my worst holes and clean and fill again.
Thanks!

[VA-Sawyer]

You just need the correct words, and the correct sequence in which to say them.
It also helps to hold your tongue just right.
If you can't do that, then the previous advice is dead on.

[cj737]

I’ve never welded up a cast engine case that wasn’t a MFer to get right. They are oil-soaked, crappy alloy compounds that are decades old. Worst possible conditions to weld.

My approach has been to preheat the thing (whenever possible). Chemically clean. Scrub, grind or drill, then chemically clean again. Run a first pass, torch only at 50-60Hz with lower amperage. Scrub and chemically clean again. Then a first filler pass with 4347 wire. Peen the pass and chemically clean and scrub it. Then repeat passes and peen between. Not perfect, not without frustrating results at times, but darn near reliable in results.

[COwelder]

When you say you generously grind the porosity, do you mean you grind down to solid metal before running back over it? My experience is that it is very difficult and unreliable to try to burn out porosity by welding over it- even if contaminants have been cleaned out of the pores mechanically or chemically. I always have to completely remove the porosity (grind it all out) before building back up with weld, unless it is purely cosmetic and then it can be just buried under a cover pass. If you are just trying to conceal the porosity, turn up the amps to get it to wet out instead of donut around the hole.
I know you are using TIG, but I have also been able to minimize problems with really dirty aluminum by stick welding with Smoothcote 34 rods. A decent bead appearance can be achieved (definitely not going to look as good as tig) and obviously doesn't matter if you are just going to grind it flush.
Sounds like other commenters have a lot more experience with aluminum castings but I do repair some really nasty aluminum often enough and figured I could offer a little different take on it that may be useful.

[Poland308]

I’ve never welded up a cast engine case that wasn’t a MFer to get right. They are oil-soaked, crappy alloy compounds that are decades old. Worst possible conditions to weld.

My approach has been to preheat the thing (whenever possible). Chemically clean. Scrub, grind or drill, then chemically clean again. Run a first pass, torch only at 50-60Hz with lower amperage. Scrub and chemically clean again. Then a first filler pass with 4347 wire. Peen the pass and chemically clean and scrub it. Then repeat passes and peen between. Not perfect, not without frustrating results at times, but darn near reliable in results.

Yup. Only thing I would add is force feed lots of filler when you weld it will help float junk up to the top for your next grind session.

[Toggatug]

I'll throw my two cents for what they're worth.

I try and only use carbide tools or drill bits when cleaning the cast. Don't want anymore dust and debris getting I to pores than is already in there is my theory.


My favourite is my trusty saw blade for aluminium on a angle grinder, leaves a nice clean surface to run in over and find all the pockets of smoo.

Also whenever possible to work from both sides of the part I'll usually slit the part completely through and bevel the slit on both sides so I just have to clean up the edges and get a good bead to stick. Then the game gets much easier working off filler metal rather than the casting. Really situational but sometimes I do find it easier to make things 'worse" before it gets better.


Long and short. Cast materials are always a joy. Cast aluminium more so. Cast alum engine parts even more so.






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[Charlieman22]

Good stuff all
Had't heard of peening prior to today - but got a few suggestions to try it.
Will add that to my grind and clean regimen.
All comments and shared experience are appreciated.
Thanks!

[motox]

all the above and an aluminum-specific die grinder with a light touch helps.

[Coldman]

On top of all the above, bin the 4043. Use the suggested filler or 4047.