What I`ve used several times on different cars over the years is BAR'S LEAK available here in the UK...It`s brilliant
I had a corrosion split in my cooling system and it`s been working OK for 8 years now.
The solid form is better than the liquid form.
See http://www.barsleaks.net/
I think Halfords still sell it.
RegWort
May 2008