Welding on a car, issues?

metalgear2k2

My gf's car (N16 Almera) just failed the NCT on rusting on the "front main member" it has a few holes in it.

The guy said just to weld a few plates over them. (ill take some pics leter to show)

Is there any problems with welding on the car? (blowing fuses? etc) It would be major hassle to take it out, easy enough to weld where it is as it is.

Any help would be great.

taintabird

metalgear2k2 wrote: »

My gf's car (N16 Almera) just failed the NCT on rusting on the "front main member" it has a few holes in it.

The guy said just to weld a fe plates over them. (ill take some pics leter to show)

Is there any problems with welding on the car? (blowing fuses? etc) It would be major hassle to take it out, easy enough to weld where it is as it is.

Any help would be great.

just disconnect the battery before you do any welding and you will be OK

metalgear2k2

thanks

SeanPuddin

and your alternator. man if you're not sure this aint a DIY job.

leex

Had same issue with a 01 Primera when I NCT'ed in 2009 - my service'ing garage recommended welding but I was 50/50 whether a) this was safe and b) if it would guarantee a pass in NCT. A bodyshop recommended replacing the piece of metal and I went with that. Cost 250euro if I recall correctly. Shop around.

taintabird

SeanPuddin wrote: »

and your alternator. man if you're not sure this aint a DIY job.

no need to disconnect the alternator once the battery is disconnected the circuits broken and your alternator will be OK.

rex-x

This is very common on these and its a bolt on panel so just get a new one

metalgear2k2

Not a hope I'm getting a new one, why waste the money when the NCT dude said plate weld it and he would pass it no problem. Got it fixed last night, I work for an engineering firm, had one of our best welders sort it for me. All sorted now.

Thanks for the advice.

This can be locked up.

wildefalcon

taintabird wrote: »

no need to disconnect the alternator once the battery is disconnected the circuits broken and your alternator will be OK.

The risk is a surge from the welder goes near the alternator and blows the rectifier and diode pack.

Best advice is to disconnect both. That way you can't go wrong (as long as you have the radio code).

500sel

What about the ecu:eek::eek::eek::eek:

taintabird

wildefalcon wrote: »

The risk is a surge from the welder goes near the alternator and blows the rectifier and diode pack.

Best advice is to disconnect both. That way you can't go wrong (as long as you have the radio code).

Cant happen, once the earth lead is off the battery no damage can occur to the alternator!

taintabird

500sel wrote: »

What about the ecu:eek::eek::eek::eek:

Once the battery is disconnected all electrical systems are safe.

Merch

taintabird wrote: »

Once the battery is disconnected all electrical systems are safe.

Is that a definite?

taintabird

Merch wrote: »

Is that a definite?

Yes mate

Design_Dude

taintabird wrote: »

Yes mate

Yes indeed! common sense!

Merch

taintabird wrote: »

Yes mate

No potential for ecu damage as someone else suggested?

I know a person got some welding done and the vehicle would not start afterwards, think I was told it was the ecu
but I dont know if the battery was disconnected

taintabird

Merch wrote: »

No potential for ecu damage as someone else suggested?

I know a person got some welding done and the vehicle would not start afterwards, think I was told it was the ecu
but I dont know if the battery was disconnected

I would say they didn't disconnect the battery, a cars electrical system is a loop running from the battery one side from the positive terminal the other from the negative or earth side once the loop or circuit is broken ie the battery disconnected nothing can happen it always pays to get someone who is qualified to do that kind of work. I carry out these sort of repairs out on a regular basis and never yet had a problem.

lomb

Can also use 2 pack epoxy to fix it and a little touch up paint over it. I know of an almera that failed for the same reason and the owner did that instead.

Merch

taintabird wrote: »

I would say they didn't disconnect the battery, a cars electrical system is a loop running from the battery one side from the positive terminal the other from the negative or earth side once the loop or circuit is broken ie the battery disconnected nothing can happen it always pays to get someone who is qualified to do that kind of work. I carry out these sort of repairs out on a regular basis and never yet had a problem.

Thats fair enough, I dont know better either way regarding welding.
I'm know of how car electrical systems work, negative earth etc and have a bit of experience with electrical/electronic components but
I had thought that disconnecting the battery just disconnects the battery and some positive terminals but every other component is still connected to its circuit through the negative side (car body)
I'd still go for disconnecting the electronic components such as those in the alternator and the ecu by plugging them out? no

500sel

taintabird wrote: »

Once the battery is disconnected all electrical systems are safe.

WRONG!!!!!!!

500sel

Merch wrote: »

Thats fair enough, I dont know better either way regarding welding.
I'm know of how car electrical systems work, negative earth etc and have a bit of experience with electrical/electronic components but
I had thought that disconnecting the battery just disconnects the battery and some positive terminals but every other component is still connected to its circuit through the negative side (car body)
I'd still go for disconnecting the electronic components such as those in the alternator and the ecu by plugging them out? no

The circuit board in your ecu is just the same as one in a computer, ask anyone working on pc's what is the biggest risk when working on a PCB. If you need to weld on a modern vehicle you need to use a surge protector to make it safe. Modern welding techniques minimise the risk of damage but dont eliminate them and with cars now having as many as 70 ecu's(Not your N16, that has only 4 or 5) its a chance not worth taking .

Muckie

500sel wrote: »

The circuit board in your ecu is just the same as one in a computer, ask anyone working on pc's what is the biggest risk when working on a PCB. If you need to weld on a modern vehicle you need to use a surge protector to make it safe. Modern welding techniques minimise the risk of damage but dont eliminate them and with cars now having as many as 70 ecu's(Not your N16, that has only 4 or 5) its a chance not worth taking .

Worth their weight in gold!

Save frying the ECU

Merch

500sel wrote: »

The circuit board in your ecu is just the same as one in a computer, ask anyone working on pc's what is the biggest risk when working on a PCB. If you need to weld on a modern vehicle you need to use a surge protector to make it safe. Modern welding techniques minimise the risk of damage but dont eliminate them and with cars now having as many as 70 ecu's(Not your N16, that has only 4 or 5) its a chance not worth taking .

A surge protector on the power supply to the welder?

Dupont

we use one that clips onto battery and can weld away,forgot it once and was dreading it wouldnt start.i was told that a surge could set off pre tensioners in seatbelts or airbag??(anybody ever use spotwelder thats used for pulling out dents,seemingly your not allowed to use if you have a pace maker fitted)