After water locked the no6 cylinder last week, I removed the head to replace the gasket (replaced 4 years ago too!) but discovered that the no6 chamber was corroded and venting to the coolant passages!
I have several options,

1 strip the head, get it welded, machined and re-install (most work)
2 buy another head (most expensive)
3 drill out the corrosion pocket, tap and thread in an aluminium bolt, file flush. seal with j-b weld (close to valve seat!!)
4 prepare, clean and fill with j-b weld. (cheap and fast)

I'm interested if any of you guys have used jb weld for such repairs?
M103 engine. 1991 300ce. A picture of the chamber is now on my gallery