Welding an NLA BMW exhaust box

  1. Randall977

    Randall977 Member

    Messages:
    187
    Location:
    Oxfordshire
    Having said 'I'll never do another car project' last year, I've predictably bought another car project. Not like the last two, which were basket cases, this one is in pretty good condition really - especially for an E24 - but some minor welding is still needed here and there.

    E24-Main.jpg

    On issue is the exhaust back box which is no longer available and is shaped to fit neatly between the fuel tank and spare wheel well. I could get a SS one made up but I'd like to keep the original, partly for the sound and also because it is tailored to the car. As you can see it has rotted through and I'm thinking about welding it up - maybe with new tail pipes too.

    Is this feasible and do I need to be careful of unburnt fuel residue (it was last run in 2009)?

    Planning to do it with galvanised metal.

    E24-Exhaust.jpg
     
    zx9 likes this.
  2. gaz_moose Member

    Messages:
    633
    Location:
    tamworth staffordshire
    exhausts tend to rot from the inside outwards, so the inside will be twice as bad as what you can see. I would be looking at a replacement or making a new one from scratch.
     
    james butler likes this.
  3. cumbriasteve

    cumbriasteve Moderator Staff Member

    Messages:
    8,412
    Location:
    Cumbria UK
    Using galvanised steel means the areas to be welded will have to be ground back and any protection will be burnt off by the welding process so no real benefit gained and you are still left with a box of rust that probably won't last 12 months.

    Replace or remake would be my choices.
     
  4. Cobbler

    Cobbler Codger bodger

    Messages:
    2,985
    Location:
    Gloucestershire UK
    I know this doesn't answer your question, but I had a 2 litre E30 some years ago. I dropped off the back box which was original BMW & the whole bottom was rotted out, but didn't appear to leak, when I looked at it, there seemed to be another internal box within the casing which was some sort of stainless. I cut away the complete lower part & recovered it. This lasted at least 4 years & was still ok when the car was sold. Hopefully if yours is a BMW system you will find the same.

    Edit. Whenever I've done exhausts, I've never even thought about fuel residue & I've patched up a fair few over the years & I'm still here typing this
     
  5. colnerov

    colnerov Member

    Messages:
    2,422
    Location:
    Nr Gatwick UK
    Hi, There's unlikely to be any fuel residue but there will be a lot of soot which will give off acrid smoke.

    Colin
     
    Wozzaaah likes this.
  6. Randall977

    Randall977 Member

    Messages:
    187
    Location:
    Oxfordshire
    Thanks for the advice. I think I'll chop it off and maybe cut the bottom off to see what it's like inside. If I can repair it and it only lasts a short time this will at least enable me to get it OTR.
     
  7. slim_boy_fat

    slim_boy_fat Forum Supporter

    @Randall977 Which engine do you have? BMW are very good at supplying parts for their Classic models and it might be available to order. A random model selection here shows the box as still being available [that's a great site, btw ;)]

    http://www.realoem.com/bmw/enUS/showparts?id=5182-EUR-08-1986-E24-BMW-628CSi&diagId=18_0084

    EDIT: When it comes to spares, keep Quarry Motors and FABDirect in mind, they're both long-established BMW breakers and might just have parts you need on their shelves [although modern models are the mainstay of their businesses].
     
  8. Randall977

    Randall977 Member

    Messages:
    187
    Location:
    Oxfordshire
    Great link, thank you - I try the breakers too :thumbup:
     
  9. Kent

    Kent Member

    Messages:
    8,345
    Location:
    Bowland, Lanacshire,UK
    Generally you will get a new ss one made for less than a main dealer price on std for a rare car from main dealer.
    As there isn't the part available, it's a very simple desision. Don't make your own back box and a back box repair is very temporary as a generalisation
     
    Brad93 likes this.
  10. p0689109 Member

    Messages:
    1,291
    Location:
    stoke on trent,england
    I have a Renault Scenic 1 and its back box is a box within a box and the outer box has started to disintegrate but still does not leak too.
     
  11. Brad93

    Brad93 M J B Engineering

    Messages:
    2,920
    Location:
    Essex
    That needs a new exhaust building.
     
  12. tinker jim Member

    Messages:
    109
    Location:
    birminham
    Is that the 6 series csi by any chance
     
  13. Randall977

    Randall977 Member

    Messages:
    187
    Location:
    Oxfordshire
    Yes it is - do you have a spare rear exhaust box? :laughing:
     
  14. tinker jim Member

    Messages:
    109
    Location:
    birminham
    No no backbox sorry just a iconic car for me not like all these so called bmw ''s they make now.
     
  15. Rig Pig

    Rig Pig Member

    Messages:
    2,507
    Location:
    Narrwich! U.K.
    I'd be tempted to fit an after market universal tubular exhaust, give the old beast a bit more roar!
     
  16. james butler

    james butler Member

    Messages:
    556
    Location:
    birmingham england
    i would give bmw a ring as like slim boy fat says they do keep a lot of old school parts.
    i managed to get a new e36 filler pipe brand new not so very long ago.
     
    slim_boy_fat likes this.
  17. slim_boy_fat

    slim_boy_fat Forum Supporter

    And not just 'what they happen to have 'kicking around in the stores' [which are space-limited nowadays]. It's Company policy to be able [as far as humanly possible] to keep all their models in the Classic category alive, even if the parts will definitely have to come from Germany.
     
    GW8IZR and james butler like this.
  18. dannyp Member

    id say that exhaust is done,

    if welfing exhaust up i found it best to scortch them with the gas axe first get everything near whats got to be welded red hot and burn off all the soot, it won't make it nice to weld but it make it less nasty.
     
  19. GW8IZR

    GW8IZR Blue fire from an undead dragon

    Messages:
    1,847
    Location:
    Anglesey
    nice car that.
     
  20. chris y Member

    Messages:
    107
    Durham England
    Just a note on the "box within a box" comments, its not that, its that the shell of most exhaust muffler boxes is double skinned for radiated noise reasons, and sometimes the two skins can be made of different material in an attempt to keep cost down while having a long enough service life.

    I don't think I'd be repairing that one to be honest if its a long term plan, it might get you on the road for a while though.
     
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