Its an engine case for an old Lambretta and ive got a small crack inside the case by a threaded hole for one of the gearbox studs.
I think the case is aluminium, can it be welded up?

Cheers,
Muffster.

 

not unusual for motoX engines to have cracks welded up,
not ideal but it works so should be possible(depending on the damage obviously)

 

its just a small crack, and its internal so it doesnt have to be too cosmetic. can i mig it/
Muffster.

 

no i would not mig it ,its not good enough ,but it could be tig welded which would be much better you would need to clean it with solvent so there is no oil contamination & if you can grind into the crack so the weld can get in as far as possible so it will be a good strong weld .or you could use a dye grinder to get into the crack then you can drill the hole & re tap it .

 

I had a Fireblade I bought as salvage and it had a crack in the engine casing, I got a good repair using an epoxy resin like the ones you get in Halfords. So long as it is a thin crack and there's no chunks of the casing missing. Worth a try anyway.
This is the sort of thing:

http://www.halfords.com/webapp/wcs/s...egoryId_165691

Or..., I've just bought another product from Halfords that you might like to ask about. Here's the link:

http://www.halfords.com/webapp/wcs/s...egoryId_165691

Anyway, food for thought. I think the first one would work better for what you want, I bought the second one more for filling in curbing on alloy wheels, it's more of a putty whereas the first one will be easier to get into the whole crack and seal it properly.
Worth asking them about, it worked for me at the time.

 

You can mig it no problem, IF you have a decent high amperage set, as you need to put so much heat in, it dissipates heat so effectively(alloy), best bet would be tig though, easiest way is to drill a small hole at the end of the crack then fill that and the crack after gouging out a bit.
tabetha

 

Had mine alloy welded and it was still leaking, got some glue stuff fa halfords and never had another problem with it