Smoking alternator

Discussion in 'Mech Tech' started by pirateringo, Jun 6, 2020.

  1. I have a type 4 2l engine, I noticed the battery light on the dash stayed on when key was taken from ignition. Trying to work it out I started engine looked in engine bay and the alternator had a puff of smoke coming from it. Pressing the accelerator results in the light becoming brighter. I'm assuming I need a new alternator and if so can I do it without dropping engine?
    Cheers
     
  2. Zed

    Zed Gradually getting grumpier

    You can remove it with the engine in place, just a few bits of tin to remove.
     
  3. Cheers guys, just gotta work out which one to buy a bosch or repro
     
  4. 77 Westy

    77 Westy Supporter

    That shouldn’t need a lot of working out.
     
    Little Nellie, snotty and Lasty like this.
  5. You`ve got a choice ....

    Bosch .
    OR
    get used to the guarantee small print ...

    :hattip:
     
    Moons likes this.
  6. davidoft

    davidoft Sponsor

    Buy Bosch and If your alternator is smoking I would disconnect the battery
     
    snotty likes this.
  7. Check someone hasn't already swapped it for an aftermarket one where the + stud is too long, if they have you will be requiring a new alternator loom !
     
  8. mikedjames

    mikedjames Supporter

    The fact the light gets brighter may point at the shorting bolt and the smoke is from melted insulation. Main alternator output goes low because of short. Blows big diodes and stays low. Regulator winds up field current to compensate for low output voltage. Warning light diodes still working so voltage goes high to warning light.
    Probably still have a working regulator, dead alternator, melted wires.
     
    pirateringo and Moons like this.
  9. 77 Westy

    77 Westy Supporter

  10. Zed

    Zed Gradually getting grumpier

    I had three or four type-4 alternators I hoped to make one good one from. I did manage to do that but every one of them had a melted and burnt loom. They were all Bosch originals. What that indicates I have no idea.
     
  11. ginger ninja

    ginger ninja Supporter

    It’s a bit of a faff changing it with engine in but can be done. If you have an inspection hatch it’s much easier. You will need swan neck spanner at some point (can’t remember what size but 8, 10, 12, 13 should cover it) and a very big socket to undo the fan shroud from the back. I think it was a 36 but I’ll go check for you in a minute.
     
  12. type 4 :)
     
    ginger ninja likes this.
  13. ginger ninja

    ginger ninja Supporter

    Oh yeah not the same fan shroud. Soz.
     
    3901mick likes this.
  14. Zed

    Zed Gradually getting grumpier

    If swapping it out, I wholeheartedly suggest loosing the pulley nut while the alt is still in situ and the belt is tight.
     
  15. Get yours reconditioned

    Sent from my Pixel 4 using Tapatalk
     
    Razzyh likes this.
  16. Right just got the alternator out didn't take of pulley but I would have if I'd read this first :(, anyway on inspection of the alternator the cable attached to d- was shorted out with green residue on it. Barely attached to the connection. Could this be the reason, does that mean my alternator could be ok? Is it possible to test my alternator with multimeter? Was a bit of a bitch getting alternator off
    , time for a beer :beer:
     
  17. Miked James I think you might have hit nail on head. Slightly melted wiring causing smoke, the regulator is only 6 months old as I fitted a new one when installing split charge relay. Not sure if this alternator is bosch or not. Has a silver sticker saying original vw/audi part but it's fairly worn looks old.
     
  18. When I bought our USA import 9 years ago found output was low on original bosch (2.0 type 4) so had a new Bosch one fitted and new reg. Was perfect for two years then suddenly had a short from alternator to starter and burnt out cable. Had a new repro alternator and reg fitted which was perfect for 200 miles then started to get quirks. Sometimes the charge light would take a few mins to go out when started after a few days/weeks then be ok the rest of the day of start. Even a quick blip could sometimes work but is was like this for years and kind of got used to it. Tried several new regs thinking it was this and also checked dash earth /bulb. Would go for a new Bosch again if I had to.
     
    pirateringo likes this.
  19. Razzyh

    Razzyh Supporter

    This

    Try these guys. Used them myself


    https://www.unitexchange.com
     
    pirateringo likes this.

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