Welding on a BMW (or any modern car)

[Jazzbass]

Any time I or someone else has done any welding on my 911, we remove the DME completely from the car to be safe.

So that got me thinking - what if you had to weld on a modern car like my E90. NFW you can remove the electronics like you can in my 911. Any one done this? No big deal or is there something special you need to do before hooking the car up to the welder?

I almost had to resort to the old "weld a nut to the transmission fill plug" because I'm a f**king gorilla and stripped the 8mm hex out. I got the fill plug off with an air chisel, but it got me thinking about the welding issue.

[Trak Ratt]

I fried several of the 964 electronic components by just using my big charger "hot start" option for countering a dead battery. Can't believe error-ing on the side of caution for actions like this isnt prudent. Though I've seen auto body shops weld on chassis without even disconnecting the battery. Maybe like many things "it depends."

[Vicegrip]

Keep the work clamp clean, tght well grounded to the base metal being welded and close to the work and worry little IMO. For example the old rule of thumb to disconnect the positive term is not based on any real protection value. Many people do only that and weld away thinking that the lack of damage was due to their precautions. The electrons want to go from work to clamp or vice verse not wander off where they meet with resistance or lack the capacity to cope.

Doing some. AC TIG with high frequency? You might want to shied the more sensitive stuff.

[Jose]

I always disconnect/remove the ECU when welding on the car (as did BimmerWorld when they installed my cages in the E46 and E92). Not sure if it could have been fried if I didn't, but they're expensive and it's a precaution that's easy enough to do.

[cmartin]

That seems to make sense but on a modern car with multiple ecu's/control modules (think benz) it's not very practical IMO.

Most everything is connected with ground straps so to me it's disconnect all or nothing. Nothing usually wins out.

[Vicegrip]

I will see what the Manufactures requirements are for welding. I can ask the body shop manu cert holding techs.

[Lupin..the..3rd]

Time to upgrade to a digital welder. Don't forget the anti-virus.

[Vicegrip]

OK the word from I-car, MB and Audi. Disconnect the battery. No welding within 12 inches of any wire. No removal of ECUs mentioned.

[cmartin]

Thanks for the follow up. Now to figure out the proper method of battery disco. :)

[Jazzbass]

OK the word from I-car, MB and Audi. Disconnect the battery. No welding within 12 inches of any wire. No removal of ECUs mentioned.
Awesome - exactly what I was looking for. Thanks!

[Lupin..the..3rd]

The electrons want to go from work to clamp or vice verse not wander off where they meet with resistance or lack the capacity to cope.
Makes sense, but then I wonder why the official recommendation to disconnect battery? Work and clamp are many feet away from the battery.

[Vicegrip]

dono. Never quite understood that one and I don't have enough trial and error to render a theory. Have yet to fry an ECU or other similar type device.

I have messed up the TV images sets 2 houses away while AC tig welding using a 20HZ secondary wave along with the standard 60 cycle. Lady asked me if my TV was acting up and when I asked her what and more so when I triangulated back to my welding times. come to find out she was calling the cable co and even had them come out and was getting ticked after it kept happening but never when they were there. "Gosh, that IS strange. Well I better be going now" :roll:

I did a test and sure enough any kind of decent amps and it made a nice herring bone like in the olden days when a plane flew overhead. I found that wrapping the torch and work cables around each other from the machine to as close as I could and still work cleared things up.

I will see if there is more explanation to the battery thing.

[roundel]

dono. Never quite understood that one and I don't have enough trial and error to render a theory. Have yet to fry an ECU or other similar type device.

I have messed up the TV images sets 2 houses away while AC tig welding using a 20HZ secondary wave along with the standard 60 cycle. Lady asked me if my TV was acting up and when I asked her what and more so when I triangulated back to my welding times. come to find out she was calling the cable co and even had them come out and was getting ticked after it kept happening but never when they were there. "Gosh, that IS strange. Well I better be going now" :roll:

I did a test and sure enough any kind of decent amps and it made a nice herring bone like in the olden days when a plane flew overhead. I found that wrapping the torch and work cables around each other from the machine to as close as I could and still work cleared things up.

I will see if there is more explanation to the battery thing.


Ive had a drink or two tonight, but this post rocks!