Bilal928S4

I am currently working on my other car a BMW 735i to change out the drive shaft and broke the stud holding the exhaust down pipe to the header.
So it has been soaking in the acetone/ATF solution recommended by Wally, but it does not seem to be working.
So the question is for a VERY part time DYIer what make sense to get?
An oxy acetylene torch set up or a welder?
As I have heard that welding a nut on the stud would heat it up adequately and allow it to be taken off. I especially like that idea as many bolts on the 928 are in areas where an open flame is not recommended. When I was doing my tb/WP one of the bolt holding the tensioner would not come out. I tried everything but could not get the bolt (or the stud portion as the head had a broken) even trying with heat from an acetelyne torch. In the end ended up leaving it per the combined recommendations here. While heating the bolt I was very concerned about damaging the wires in the area. A welder might have worked better.
Any suggestions?

123quattro

I think you'll have more luck welding a nut on to remove it. I also think having a welder around is much more useful than a torch.

17prospective buyer

Welding would work the best IMO. Just make sure you clean up the area you're using to ground it out to get sufficient current flow, and put the ground as close as possible to the stud you're welding. Won't fry any electronics if you don't put the ground too far away from where you're welding.

WallyP

I would never use any electrical welder on a 928 without disconnecting the ECUs.

I have both a small aircraft torch and a MIG, and my usage overall is probably two thirds torch, one third MIG. If you were getting a torch just for occasional usage, I would suggest the small aircraft torch and small tanks. For heavier work and serious fabrication, a bigger torch would be better, but for my usage, the small outfit is much better.

Either torch or MIG takes practice. Check at your local schools, and see if any offer welding classes. If you are not willing to take a class, perhaps you don't need any type of welder.

outbackgeorgia

Wally is 100% correct in my experience. I also use a small "Airline" torch most of the time. Electric welding on a 928 can be expensive without disconnecting electronics. In theory, electronics should not be affected, BUT are all of your grounds perfect? Carefully shielding the work area from heat, and using the correct torch tip is essential. Propane torch is not very useful due to the low heat and lack of ability to concentrate the heat correctly.
Dave

Bilal928S4

What is a small aircraft torch? Is it acetylene only?

G8RB8

If you use an arc welder keep the ground as close as possible to the weld. Also ground the car itself to a metal water pipe or ground rod.
After you weld the nut on the stud you have to cool the stud and the nut to shrink them. Try NOT to cool the surrounding metal.

docmirror

You can weld with a torch, or heat things, and no electric transfer. I don't use my torch often, but when you need it, you need it.

O.B.1

+1 on grounding as close to work area as possible. I use my welder a lot more than my torch's but always not on cars ie...gates ,fences ect
For what it worth.

outbackgeorgia

Small aircraft torch is Oxy/Acet, just much smaller than the more common ones. Mine is a "Smiths Airline" but there are others. I have a cutting head, as well as 4 tips of different sizes.

STRIKEMASTER

One trick I've used a time or three: 1 heat up area /w a torch (MAP gas, not propane, i'ts hotter), 2 put a piece of DRY ICE on the stud(use gloves /w DRY ICE), 3 let everything normalize,wait till everything heats up/ cools down. THEN try to remove the stud. Theoretically, the dry ice will shrink the stud enough to make it break loose from the block and be easier to remove. DON'T mess with the stud while it's cold, it WILL break off. DRY ice is -85F and will cool down the stud almost that much.

Randy V

Aircraft torch?

outbackgeorgia

Airline torch

outbackgeorgia

Try this link, next post-"Airline" is just Smith's brand name for their small Oxy/Acet torch set.

outbackgeorgia

Try this:
http://www.aircraftspruce.com/catalo...dtorchhand.php