On Tue, 26 Jan 2010 13:38:57 -0800 (PST), JimK wrote:

intriguing - pinholes at the top of rads??! - only ones I've ever
dealt with (tho not many) were at bottom near either valve...

I've had 'em near the top in the face of the vertical "tubes" and the
horizontal top "tube". I suspect that the system had never had any
inhibitor in it and was a good ten years old when the holes appeared,
in a couple of rads. I soldered little bits of copper over them,
drained the system and refilled with inhibitor no more holes
appeared.

--
Cheers
Dave.