cracked case

[tonyiad]

Recently I found a crack on my 2L engine case, where a stud screws directly into the magnesium. I really need some advice on how best to deal with it and prevent it becoming a serious problem. I could leave it, seal it or perhaps use JB weld, I just don't know.
I’m guessing to fix it properly would require an engine strip, but that may or may not be possible this year and be frighteningly expensive.

[911hillclimber]

If you cant strip the engine to have it welded and tapped true after then if it isn't leaking oil I would leave it alone, but protect that crack from corrosion (which will make the welding so much harder later on) and JB would be a good material to use after really cleaning the area and the crack as deep as possible.

As it has cracked I presume there is a tread issue or over tightening responsible and you don't want that crak propagating further so a strip wilbe due soon.

Welding magnesium castings is a specialist job, but quite easy to find people to do this usually in the motorsport industry.

[tonyiad]

I suspected it had been over tightened, not by me but by someone who thought they were helping. For now I’ll give it a good clean and use the JB but, I guess I’m looking at a rebuild, something I was trying to avoid.
Thanks for your advice.

[redrobin911]

Speak to Alan Barker from EMP engineering, they weld both aluminium and magnesium crankcases - he'll advise on best way forwards.

[tonyiad]

Thanks, I'll certainly give Alan a call.

[Cortina]

I can't actually see a crack in the photo ? ............ I see what looks like two casting "lines" - above and below threaded hole . Maybe just photo angle or my bad eyesight ??
If it's just a crack on the bottom - you MAY get away with an "in situ" spot of TIG (loosen bolt - good clean,weld and refit bolt to a lower torque ?) , to hold things together , untill you get opportunity to strip , fix properly and rebuild ??

[gridgway]

I can't actually see a crack in the photo ? ............ I see what looks like two casting "lines" - above and below threaded hole

Yes, looks like that to me. Would need a photo of the other side of the raised casting line. Or even file off the casting line to get a better view?

[911hillclimber]

Razor blade.
If you can get some in along the line...it's a crack.

[Cortina]

Razor blade.
If you can get some in along the line...it's a crack.

..... and even if you can't ..... it could still be a crack !!! (Razor blades go in straight lines ... sometimes cracks don't)

[911hillclimber]

OK, the corner of one!
Could be the casting flash 'line' but if oil tight I would leave it.

[tonyiad]

Thanks guys. I've made plans that will lead to a rebuild later this year, it was always on the cards. I'll keep an eye on this crack and if it gets worse I'll use JB weld to hold it.