Welding Magnesium - Porsche 911

I continue to accumulate parts for my 906 build and received this engine case last week. It's magnesium. Unfortunately, it has a repair that appears marginal to me. The repair is to the threaded fitting area in the lower left next to the left oil return tube hole. I've welded a lot of steel and some aluminum, but never magnesium. Does it look as bad to you guys as it does to me? The voids are in the surface and the case was sold as a useable part. The hole is threaded and as far as I can tell, it part of the oiling system. There is no damage on the inside of the case. It appears that the raised boss was reattached.

Here's another case for comparison purposes:

Air test it and see if it blows bubbles?

Dont try to fix what aint broke!

My guess is what ever contamination is there will boil out of a new weld. (especially if the problem is in the parent metal).

A new weld might have to be chased all the way across the block (and then still leak)!

Turbo oil drain?

I know nothing about welding, but how many psi does that oil port see? Even if porous, could epoxy help seal it up if the psi isn't so great?

You can weld magnesium? The stuff the sell as fire starters and make fireworks out of?

Damn. Ain't it a crazy world!

You can weld magnesium. Tig in a purge chamber with the proper rod.

From the picture that does not look like a bad job. you would be hard pressed to find someone to do better IMHO.

I think magnesium can only be welded by a focused beam of gamma rays in the vacuum of deep space. I'm pretty sure you are going to have to JB Weld that.

http://www.lincolnelectric.com/en-us/support/process-and-theory/Pages/welding-magnesium.aspx

Looks like I was wrong, you dont need a full purge chamber. I seem to remember being taught (lincoln seminar) that a purge chamber was best though.

A purge chamber is best because if you weld mag in the open and something happens to cause the mag to start to burn there is oxygen present the moment you remove the TIG torch from the weld area. That oxygen will support that combustion. It that happens then you best just stand back and try to keep the fire from spreading! In a purge chamber there is no oxygen to support combustion so the mag can't burn.

TRoglodyte wrote: From the picture that does not look like a bad job. you would be hard pressed to find someone to do better IMHO.

I would be in the same camp, Mag looks like E36 M3 when you repair it no matter what including the skill of the operator. Under 80 PSI I doubt its going to have issues but you can always put a ton of pressure on it and see what happens.

Apexcarver wrote: You can weld magnesium. Tig in a purge chamber with the proper rod.

And even then, keep a bucket of sand around in case it ignites.

To answer a few questions:

I think an AC Porsche runs 4-5 bar oil pressure. Since I use measurements that relate to the various body parts of English royalty, I'm not sure what a "bar" is, but I thinks it's around 50 psi. That's adequate for one of my MGs.

I plan to spackle some JB Weld over the pits since after studying the picture it looks like there was a crack at 12 o'clock rather than parts broken off. Not sure why the guy spooged on so much weld other that for reinforcement.

I'm assuming/hoping that whomever did this knew how to weld Mg and it's structurally OK - just ugly. On the other hand, I've never let ignorance or lack of skill stop me from attempting something requiring expertise and years of practice.

Unless I find another 3R case cheap, I'm proceeding with wreckless indifference.

1 bar is 14.5 psi so 5 bar is a little more than 50psi .

10psi/1000rpm is the figure I remember from my 911 days. You can see 60 psi if the oil(all 12 quarts of it) is cold and the revs are up.

My first thought was, "if/when you try - make sure the video camera is rolling..."

Problem I see is getting the part clean enough to weld. The pits in that weld were caused by some sort of smegma boiling out of the puddle as it cured. Said smegma could be oil byproducts or magnesium corrosion.

Magnesium wheels are notorious for becoming brittle with age. I suspect that the same mechanism that creates the embritlement is going to come into play as you try to weld the old casting.

As to how hard it is to do, from the Youtube videos, it looks about the same as welding an alloy casting. A lot depends on how good of a TIG welder you are.

use wicking Loctite #290, it will suck back into the holes to insure they are sealed up.

Somewhat related question for the OP: Have you located a 906 body? They're beautiful cars.

weedburner wrote: use wicking Loctite #290, it will suck back into the holes to insure they are sealed up.

That's good to know. Never heard of that before.

Woody wrote:

weedburner wrote: use wicking Loctite #290, it will suck back into the holes to insure they are sealed up.

That's good to know. Never heard of that before.

aka Locktite green

The pores left over should help anchor the JB Weld, also the JB Weld is safe to 500 degrees. Finally since the JB Weld is more paste, then putty, it should fill and flow better then some other compounds. I would find a paper oil change washers or similar and mount it along with the oil line before you use the JB Weld... once set, but before cured, remove the fitting and washer. This should allow you enough room to repair the area, while not infringing on the threads requiring Dremel , or other type of clean up after

kb58 wrote: Somewhat related question for the OP: Have you located a 906 body? They're beautiful cars.

Yes, I have an original take-off body. I still need doors and a gearbox... and time, but I have most of what I need to make the Locost I always wanted. Speaking of Locosts, who has the GRM-family Locost now. I sold it to Foxtrapper and he sold it to someone else, who, I think sold it.

Googling the Loctite now - many thanks for that!