A pocket of impurities is very unlikely. That's sort of how the casting process works - so that you don't get that in there. OK, it's possible to get a sand inclusion I suppose, not every casting is a good un, but I can't see it on a casting like this which would have been batch cast, probably machine cast too.
I didn't look at the link, but any of these chemical metal repair putties or mixes would work. Honestly even Aradlite shoved in there would work. This is a tiny hole that will have no pressure at the back of it. It's rough so there will be a good keying of the filler and it's not straight so the plug will be locked in there. Filler is the way to go. Leave a little mushroom inside and out so that it can't come out and any pressure that does come to bear against it is spread out and it'll be fine. I used to use Devcon by the bucket load to fill castings.
Chris
I didn't look at the link, but any of these chemical metal repair putties or mixes would work. Honestly even Aradlite shoved in there would work. This is a tiny hole that will have no pressure at the back of it. It's rough so there will be a good keying of the filler and it's not straight so the plug will be locked in there. Filler is the way to go. Leave a little mushroom inside and out so that it can't come out and any pressure that does come to bear against it is spread out and it'll be fine. I used to use Devcon by the bucket load to fill castings.
Chris
