Welding

just keep the earth clamp close to the work and on clean metal. I have welded hundreds of cars and have never seen an electronic problem afterwards.

This is on a wheel arch , she has paint bubbling so i assume that it has a few perforations ( it looks like the prevous owner has clipped a bollard or the likes in the past and the bodyshop never properly sealed under the wheelarch) , just going to strip it back both sides , cut back the rust fill with weld if its not to bad otherwise weld a piece in , lead load it , rub down and respray

Disconnect the battery and ground the positive cable.

quite a few cars put the rear wiring loom directly laying over the arch and it can be very easy to cut through it or set fire to it, so have a good look first, also many have foam around there which can go up well and has fabulous smoke effects.

Unless its a prestige or classic car, I doubt I'd bother. Rub it down to good metal, treat with something like Dinitrol, fill what needs to be with bodyfiller and repaint.

Conor gurgled happily, sounding much like they were saying:

Which'll do sod all if the rust is coming through from inside, as it undoubtedly is. It won't even delay the inevitable oncoming MOT fail on structural rot.

Thanks

No its her fiesta , its just that i have lead lying about

Thanks

steve robinson brought next idea :

Arc will simply blow holes in it, you need mig.

I was always told to disconnect the alternator first, which is what I always do. I note that nobody else here has said to do that. Maybe it's not necessary.

Rob Graham

It happens that Rob Graham formulated :

The alternator is one of the more robust parts installed on a car.

It'll still die if you weld through a cable attached to it though. As will most things on a car , battery lead attached or not.

I'd be more worried about things with a microprocessor.

I don't think it was actually the alternator that was at risk but ancillary bits like voltage regulators. But I'm not sure whether they are part of the alternator on modern cars or not.

They are built in and fairly robust, they have to deal with spikes of a couple of hundred volts.

Yes, they are far more at risk.