Aluminium TIG welding nightmare
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  1. #1
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    Aluminium TIG welding nightmare

    Hi,

    I'm having some trouble welding an oil pump from a BMW M70 engine.

    The problem is just as I light the torch the arc becomes green and wanders. The puddle starts getting porous and flaky. (see attached image) left is the oil pump, right is a part cut off from the gearbox. Started the torch and just let it sit for 2-3 seconds with same settings.

    This only happens on the oil pump, I have tried several different materials and generally don't have problems TIG welding aluminum.

    Any feedback is appreciated.

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    Last edited by Snake____1; 05-28-2019 at 06:01 PM. Reason: Forgot image

  2. #2
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    Re: Aluminium TIG welding nightmare

    Romping the peddle harder will straighten the arc. How fine is the tungsten grind? And what size? 3/32 is a good size for what your doing. I use 1/8 a lot

  3. #3
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    Re: Aluminium TIG welding nightmare

    Could be the oil pump is not aluminum.
    Ernie F.

  4. #4
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    Re: Aluminium TIG welding nightmare

    @motolife313
    I have a blue band 3/32 (2.4mm) lanthanated tungsten rod ground to a ball AC TIG welding, generally no problem welding other aluminium materials. But this oil pump has been a PITA... Don't have the settings in my head, but I think it was around 70A and 30% balance. Usually if I accidentally dip or contaminate the tungsten I snip it off and regrind.

    @metalman21
    Good point, haven't really thought of that yet! Any ideas how I could test this?

  5. #5
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    Re: Aluminium TIG welding nightmare

    Snake1, put a drop of vinegar on it if you get a reaction its magnesium
    Last edited by calwelds; 05-28-2019 at 06:21 PM. Reason: wrong name

  6. #6
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    Re: Aluminium TIG welding nightmare

    "Romping" the pedal at 70 amps isn't going to do much. Turn your amps up to 150ish and then stand on it till you get the aluminum to take filler metal. Hot and fast is key.

  7. #7
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    Re: Aluminium TIG welding nightmare

    Quote Originally Posted by Showdog75 View Post
    "Romping" the pedal at 70 amps isn't going to do much. Turn your amps up to 150ish and then stand on it till you get the aluminum to take filler metal. Hot and fast is key.
    Why, oh why, or where, oh where do people read that they need sooooo little amperage with huge aluminum parts!! lol We need a single ad-like page that pops up when you open www.weldingweb.com that has a dude shouting at you saying, "turn up the f'n amperage when you weld aluminum, and don't post until you do so!!"

    ...assuming it's even aluminum
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  8. #8
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    Re: Aluminium TIG welding nightmare

    Dunno. It is not likely relevant. Before John T was a TIG welder I tried to weld a BMW part for him. 4943 filler is especially nice to work with because it melts at a lower temp than most base metal aluminum. John's part would disintegrate just before it melted the filler. I believe it wasn't aluminum in the sense we think of it. I have no notion what alloys it may have, my best guess is zinc. It seemed to melt a little less heat than the filler which melts at 1150 F
    An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.

  9. #9
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    Re: Aluminium TIG welding nightmare

    Have you tried baking the part to burn off the oils? I have been doing a bunch of filthy Al castings lately and find it helps. In my case I also go over it with cleaning passes and grind out the crud. After doing that a couple times I try to get some filler in then usually grind some more. Eventually I tend to win...
    Miller Dynasty 280 DX, Lincoln 210 MP

  10. #10
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    Re: Aluminium TIG welding nightmare

    Boy John T is famous. He is mentioned in many posts.
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  11. #11
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    Re: Aluminium TIG welding nightmare

    I'd go with the 'not aluminum' too.
    12v battery, jumper cables, and a 6013.
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  12. #12
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    Re: Aluminium TIG welding nightmare

    Im gonna guess its not aluminum or its impregnated. Sometimes manufacturers will put aluminum parts in a vacuum chamber and flood it with a "sealant" Lots of EATON hydraulic compnents are done this way. Cant bake it out, cant weld it.
    Lincolin Power Wave 450, Lincoln Powermig 255, Lincoln Pro Mig 140, Lincoln Squarewave Tig 275, Miller Big 40 G(with Hobart Hefty suitcase), Thermal Arc 95S and Esab PCM875 in an already full machine shop.

  13. #13
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    Re: Aluminium TIG welding nightmare

    The green color is usually a sign that copper is in the alloy. Some sintered metal alloys use copper in the mix. Sintered metal parts are not usually weldable. Did you check the part with a magnet?
    Last edited by Denis G; 05-29-2019 at 09:50 AM.

  14. #14
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    Re: Aluminium TIG welding nightmare

    From the pic and the description of the arc I would say its magnesium. If it is aluminum I would say it is a die cast piece that uses a lot of zinc in the aluminum to make it flow better in thin areas. If that is the case it will be a struggle to weld it up nice and would need to have some experimenting done with the AC control of the puddle . The zinc wants to boil out of the aluminum and creates gas pockets that is tuff to stop. If that is the case it might be better for a beginner to solder the piece instead of weld it.
    Last edited by thegary; 05-29-2019 at 10:46 AM.

  15. #15
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    Re: Aluminium TIG welding nightmare

    Quote Originally Posted by TJS View Post
    Boy John T is famous. He is mentioned in many posts.
    Ya I know, must me a different John t because the one on here we know ain’t no tig welder

  16. #16
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    Re: Aluminium TIG welding nightmare


    Snake____1


    If it is not aluminum or magnesium, assuredly it is -

    https://en.wikipedia.org/wiki/Zamak

    AKA Pot Metal . . . The better grades have very good material
    properties - but none of the grades are weldable -


    Opus

  17. #17
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    Re: Aluminium TIG welding nightmare

    Oil pumps are going to be hard because they are extremely heavily contaminated with oil.

    Just for the hell if it, I tried stick welding some old iron oil pump gears a while back and I was just amazed how much oil was boiling out of what looked like cleaned dried gears.

    Especially if it’s cast, it’s going to be a bit porous and because if the heat and pressure it’s under, oil gets driven into those pores.

    IDK, maybe try leaving the torch on It to try to burn off some of that oil. I’m guessing you’ll have to turn the AC balance way to the positive side. Maybe try baking it for a while, I mean if it’s cast, don’t have to worry about it being heat treated.


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  18. #18
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    Re: Aluminium TIG welding nightmare

    Quote Originally Posted by VPT View Post
    I'd go with the 'not aluminum' too.
    +1

    The blackened piece looks like steel from here.

  19. #19
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    Re: Aluminium TIG welding nightmare

    So what is it after all?
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  20. #20
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    Re: Aluminium TIG welding nightmare

    Hi, sorry for the late reply!!!
    I tried @calwelds trick to determine the material, turns out it starts fizzing when in contact with vinegar. So this part turns out to be mostly magnesium, yay lucky me...
    I will most likely end up designing a new oil pump housing from scratch, probably for the best.
    Thanks to everyone who has chimed in here!

  21. #21
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    Re: Aluminium TIG welding nightmare

    Judging by the burn mark your oil pump it isn't aluminium.

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