Welding on a diesel car

[chunkolini]

My diesel Doblo needs the lug that holds the silencer on welding back on.
Do I need to disconnect the battery before making the repair.

 

[Stingray]

Yes, would be safer to disconnect!

 

[doubleboost]

No, it is safer to leave the battery connected it acts like a damper
Make sure you have a really good earth on the exhaust as near to the repair as possible
I often hold a tab of metal in the earth clamp
This is welded to the exhaust near the repair

 

[chunkolini]

I'm actually welding onto the chassis, it's the tab that the rubber bung the exhaust hangs off that needs replacing.
I'll grind back to bare metal close to where it goes and clean up the whole area.

 

[anto44]

Disconnecting the battery used to be the right thing to do on old cars but on modern cars you're better leaving the battery connected and using a surge protector or if you haven't got one then just get the biggest battery you can find and connect it to the vans battery with jumpleads. As doubleboost said it acts like a damper

 

[Robotstar5]

Just a good clean earth as near to the repair as possible.

 

[Mick Annick]

Every day's a school day, I've been disconnecting batteries before welding for 40 years...

Mind you, even that didn't help when I welded the sills on my Morris Minor some years ago, spotted a crack on the inner wheel arch so did a lovely bit of gas welding to stitch it back together, just a shame I hadn't taken the carpets out; at least the building survived...

 

[anto44]

Every day's a school day, I've been disconnecting batteries before welding for 40 years...

Mind you, even that didn't help when I welded the sills on my Morris Minor some years ago, spotted a crack on the inner wheel arch so did a lovely bit of gas welding to stitch it back together, just a shame I hadn't taken the carpets out; at least the building survived...

40 years ago that would've been the thing to do but car electrics were a lot different back then. When cars started to see more electronics they changed the guidelines for welding and stopped recommending disconnecting the battery.

 

[arther dailey]

Interesting as I was going through the manual on my iveco daily 2008, it states disconnect the posative terminal of battery if mig welding on vehicle, must double check as also thought it said unplug ecu connectors. checking as I have some floof work to do on it when we get some decent dry weather.

 

[anto44]

If you disconnect all the electronic control units on the vehicle then its only the alternator that needs to be protected, in that case I would disconnect the battery. It's rarely practical to do that on a lot of cars though. To gain access to every control unit in a car to disconnect them could take hours of stripping to do. You'd be supprised how many control units there can be in a modern car, good few cars with up to 100 control units. A lot of modern accelerator pedals have their own control unit built in to them and communicate with the engine control unit via can bus.

 

[dannyp]

modern alternator is plenty tough enough to put up with mig welding, voltages are relativly low its DC as well so capacitancs and inductances don't really do anything funky

if you want to knacker some electronics you need an AC stick welder

 

[arther dailey]

canbus,ye ivecos have them,virtually everything on them after 06 is sensored, great untill they have a fault,although the obd is a friend here.Arther

 

[chunkolini]

Job done. Thanks all.
Lying on your back in a puddle ia such fun.

 

[reb78]

I disconnect everything i can find depending on the car! Battery, alternator and ecu’s. I have no idea if i need to but it makes me feel better!

 

[Bigjoe]

Isnt it just! Hopefully i wont have to for a while

 

[ajlelectronics]

I disconnect everything i can find depending on the car! Battery, alternator and ecu’s. I have no idea if i need to but it makes me feel better!

You are probably putting the vehicle at more risk than leaving everything as is. Although the risk from welding is tiny either way, disconnecting the battery gives you a nice aerial to feed any high energy RF straight into the stuff you wanted to protect!

 

[Bryan Williams]

So what's best on my old bus ?
1995 .19 VW T4,basic fuel pump , just a soloniod , no ECU. No fancy sensors..
Had to stick weld a bolt on one of the starter motor bolts to remove it last year, just disconnected . the battery.
No problems after.
Am I OK doing this on this vehicle?

 

[ajlelectronics]

What ever you feel comfortable with in a word. I wouldn't even give it a passing thought.

 

[Burdekin]

So what's best on my old bus ?
1995 .19 VW T4,basic fuel pump , just a soloniod , no ECU. No fancy sensors..
Had to stick weld a bolt on one of the starter motor bolts to remove it last year, just disconnected . the battery.
No problems after.
Am I OK doing this on this vehicle?

Earth right next to the job then no need to disconnect anything, earth a distance away then disconnect the battery is what I do but I always try and have the earth right next to the job, then the current only travels from the weld to earth.

 

[Bryan Williams]

Earth right next to the job then no need to disconnect anything, earth a distance away then disconnect the battery is what I do but I always try and have the earth right next to the job, then the current only travels from the weld to earth.

Cheers for that.