Welding out rusted exhaust header bolts

  1. MaxH Member

    Messages:
    21
    Location:
    London
    The steel exhaust header bolts on my motorcycle are extremely corroded and either have no head, or I expect they'll round out.

    I'm planning on drilling their heads off to release the pipes and allow me to remove the cylinder head to work on it off the bike.

    Before taking it to a machine shop to drill them out, I'll try stick welding nuts onto the remaining stubs.

    First question is whether anyone has any tips on positioning the ground clamp. The outside of the head consists of aluminium cooling fins so I'm not sure I'll have room to get a clamp on those. I'm thinking on that timing chain nose space bit? (see attached)

    Second is whether I need to mitigate the head distorting with the heat, or if this is unlikely.

    Lastly as I'll be stick welding with 6013 rods, is whether there's a recommendation for DCEP or DCEN?
     
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  2. nickk Forum Supporter

    Messages:
    2,404
    Location:
    Hay-on-wye
    Can you clamp a mole grip on the timing chain tunnel?connect the earth to it.
    6013 rods ok,never done head bolts,but a few wheel cylinder studs where the alu & steel corrode together,always been successful,wouldn’t worry about distortion as the head & cam cover are clamped down & the heat won’t be for long & it’s always hot there with combustion .
     
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  3. zzr1200

    zzr1200 Working at 650 ft on open steel work

    Messages:
    3,872
    Location:
    Glapwell, Chesterfield, Derbyshire.
    You could use a piece of flat bar with a hole drilled in it and use a nut n bolt through one of head bolt holes just clean the two surfaces between the plate and gasket surface as an earthing point

    A flat washer around/over the bolt to protect the aluminium and DCEP then a but to turn or ask if someone local has a tig?
     
  4. piman Member

    Messages:
    1,734
    Location:
    Oswestry Shropshire
    Max,

    the polarity for the rod is written on the packet.

    Alec
     
  5. hotponyshoes Member

    Messages:
    2,742
    Location:
    Somerset. Uk
    If you can get a nut on there I would wind it so the stud is just not quite through the nut and fill the back hole of the nut with weld.
    That way if you need to cut the nut off or the weld gives out you won't loose any of the remaining stud.
    I would have a blow torch ready and as soon as I put the torch down blow some heat onto the stud. You really want to get it to a cherry red if it's more than 15mm or so into the head.
    Let it cool and get a breaker bar and socket and have a go at undoing it. If it does move don't go any more than 1/2 a turn out then spray a load of wd40/whatever on it and wind it back in 1/4 turn, keep spraying and going out/in until it feels loose and it should then wind out ok.
    Maybe.
     
  6. hotponyshoes Member

    Messages:
    2,742
    Location:
    Somerset. Uk
    If you are really struggling to get the earth clamp on just hold a bit of metal bar in the earth clamp and press it against the side of the nut.
    You can also strip a bit of cable if you have any and wrap it around the stud/nut and leave a tail dangling to clip the clamp onto
     
  7. Lazurus

    Lazurus Member

    Messages:
    873
    Location:
    Norfolk uk
    I got shown a trick by an experienced pipe welder, put a washer over the stud then weld a nut onto the stud the washer stops heat transfer then just wind out with a spanner, works 9 out of 10 first time, the washer is the important bit to prevent damage and the nut welding to the head, the heat goes down the stud to assist with removal. Works for me........
     
  8. steveo3002 Member

    Messages:
    5,448
    cambridge uk
    works well for me too....sometimes give the welded washer a belt with a hammer too
     
  9. merryman Member

    Messages:
    467
    Location:
    Lancaster, England
    Please don't call exhaust pipes headers. You have exactly the same situation now as when you weld a nut on the stud, because you already have a nut welded by rust onto the stud. I would heat the nut up until red hot then try to undo it, with a mole wrench if the flats are gone. If it shears, it would have done that anyway with a nut welded on. You want heat transfer by the way, the aluminium expands to help free the steel stud.
     
  10. MaxH Member

    Messages:
    21
    Location:
    London
    Thanks for the advice all, a few good tricks to try on it this weekend too.

    Bolting/plates/pliers are all great ideas for grounding.

    I had asked about rod polarity just to establish whether the extra heat from DCEP would be beneficial or risk warping (considering I'll be removing the head so it won't be clamped down). I know that my Siftrode rods can run either way.

    Re the washer, are you suggesting welding it onto the stud or just dangling it on it to reduce spatter?
     
  11. Kent

    Kent Member

    Messages:
    10,002
    Location:
    Bowland, Lanacshire,UK
    Make a few penny washers ( copper ) ok pennies ain't copper now but other stuff is .
    Genrall I sit big on Welding on nuts just build a big blob of weld and g at it while hot with mole grips
     
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