Hi All,
I removed the thermostat housing from my other halfs NC30 tonight, the bikes running cool after changing the rads so I thought I'd stick a new 'stat in.

After removing the housing, the left hand bolt hole has a crack right though it. The bolts were corroded so I presume I've caused it, and not someone else "fitting and forgetting"

So what can I do? I can't weld it without removing the cylinder which I'm not prepared to do. I can't think of any solution apart from JB weld/devcon which I'm loath to do as it's a bodge in itself. Does anyone have any ideas?

Picture is one I've found on here just for illustration.

it should be possible to weld it while it is in the frame,i have used a metal filler putty before,worked very well but i dont think it will sort this problem.

Its not under a great deal of stress so i'd silver solder it while its in the frame.

Cylinders are part of the engine so you cant take them off.

Always best to find a way of repairing/welding it first but..... JB weld is brilliant stuff especially if you use the longer setting epoxy and hardener. Takes 24 hours but my track bike has repairs using it. It is like metal concrete when set and you can drill, tap and file it. The problem here is that it's such a fine crack, you would have work the JB into it and once set, dress it back.