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Alternator affected by welding??

Discussion in 'The Garage' started by dodgedude99, Oct 30, 2005.

  1. dodgedude99

    dodgedude99 1/2 ton status

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    ok before i get the lecture about disconnecting the battery before welding i know i originally did.

    but my step son hooked it backed up when he was screwing with his power window of something, and he forgot to disconnect it again.

    i noticed it after a while of welding and disconnected it.

    after connecting it back up, the alternator would get warm and start to smoke. figuring maybe we pinched a wire or something reinstall inner fenders, fender, or a door, we checked everything again.

    well finally hooked the ground back up and it didnt get hot or smoke.
    in the 4 blocks from my dads garage back home the Battery light came on.

    could we of had screwed the alternator by welding with it still connected to the battery??

    the kid is getting really bummed about this truck, since it seems like when he fixes one thing (new floor pans) something else breaks.

    truck is a 1990 Jimmy.
     
  2. PsychoticDeadGuy

    PsychoticDeadGuy 1/2 ton status

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    i have welded on my truck alot with the battery still connected. i always disconnect the battery now but i never had any problems with doing it before. i welded on spring hangers, body holes, exhaust...no problems....
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    On a '90 K5 you NEED to disconnect the battery when you weld because it can damage the ECM for the fuel injection. It may also be just a fluke and your alternator was going bad anyway.

    I put fuel injection on my 85 K5 and I am religious about disconnecting the battery when I weld on it. On carb'ed trucks you don't have to disconnect the battery. My buddy Matt (az-k5) has done literally hours of welding on his truck with no problems to the alternator or battery.

    Harley
     
  4. PsychoticDeadGuy

    PsychoticDeadGuy 1/2 ton status

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    mine is TBI, does that count as fuel injected?
     
  5. Hossbaby50

    Hossbaby50 3/4 ton status

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    yes. It may never hurt anything but it also could. I have been told by more then one person that I need to disconnect the battery when welding on my truck because the TPI's computer can get fried from it.

    Harley
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    Your suppossed too,but..

    I always take my battery cable off before welding on my trucks (IF I remember that is! :blush: :doah: )..many times I forgot,and didn't do it until after I used a rod or two up!..but I haven't toasted an altenator yet--but I did fry a nice 300 watt amplifier in my van welding patches on the tailpan though.. :mad: :mad: ..I felt really stoopid when I turned the radio on,and all I heard was squealing--..I knew right away what happenned.. :(

    I've watched friends weld on their cars and trucks with arc welders,and seen the tailight bulbs light up and flash,or the dash lights come on!..only once did a bulb burn out on my friends cutlass though..guess they were lucky!.

    I guess the diodes in the altenator can fry easy with the high surge of ac current from the welder..you might be able to resurect it with a new diode trio and brushes,but altenators are fairly cheap at junkyards and places like Autozone..I'd just bolt another one on--but you might check for shorts first,you might have pinched a wire,and I'd hate to see you toast ANOTHER one!.. :doah: :crazy:
     
  7. az-k5

    az-k5 1/2 ton status

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    I have never disconnected the battery on my rig (Q-jet, truck has no brain). That is including all of the welding I have done from bone stock on 31's up to its current tube-truggy creation. I have never had a problem with the alternator. I do have very good ground wires to the body, frame, and engine however.
     
  8. miniwally

    miniwally 1/2 ton status Premium Member

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    I have never disconnected batteries to to anything to a truck. Not that it is right but I think the forgiveness level is pretty high.
    The only thing that I do is place the ground as close to the weld area as possible to make sure that I am not trying to ground through the entire vehicle.
    For large amounts of welding the battery always seems to be disconnected for other things anyway so thats how I have gotten away with it.

    I would doubt that you fried the Alternator by welding on the vehicle. It can happen but is probably rare. Probably did more damage by running with out the wiring hooked up correctly.
     
  9. dodgedude99

    dodgedude99 1/2 ton status

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    actually the truck was never started with the battery terminals backwards.
    it was more he hooked the + to the - first, then started to connect the - to the + and it started arcing at the terminal right there and he knew that wasnt good and then noticed it was backwards.

    Anyway, i took the alternator to Advanced, they tested it, it was no good, i think it was just coincedental, since the bearings in the alternator sounded lovely.
     
  10. randy88k5

    randy88k5 1/2 ton status

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    Sorry for the hijack, but I think its related

    Just out of curiosity, what do you all think about the onboard stick welders. I was thinking about eventually getting one. Im currently running TBI, and I have been concerned about this very thing.

    Every time I weld on the Blazer, I disconnect the computer, ign module, and pull the radio fuse. Never had a problem yet.

    But with the onboard system, the car needs to be running. Is this safe for the electronics? What do you all think. Id hate to throw down money on one, and find out I cant use it on my own vehicle.
     

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