That plastic is polyethylene and the only epoxy I know of that will
glue it together is Gougeon Brothers G-Flex resin and hardner.  Go to
their website or google G Flex epoxy and get to their website that
way and find a marine dealer near you that sells it.  Their factory
is in Bay City MI, so there should be plenty of retailers out
there.  It's not cheap, but then there are few epoxies that will
structurally bond polyethylene, and this one works.

DM&FS

At 11:16 AM 8/2/2011, Gregg Carlen wrote:
>I don't have a direct answser for you, but as a field repair, I've used
>2-part expoxy (the kind you get from a local hardware store) to fill the
>cracked seam as best as possible until I could get a replacement tank. It
>worked just okay when applied from the outside for a day or two, then I
>drained the tank and applied it on the interior and it worked for the rest
>of the week until I had a new one to replace it with.
>Hope this helps.
>-Gregg
>
>On Tue, Aug 2, 2011 at 9:26 AM, j kulina <redbluephish@hotmail.com> wrote:
>
> > On the way to camp with the family and broke the alternator belt which, I
> > believe flew up and cracked the coolant expansion tank on
> "BlueJean", our 90
> > MV. Got a new belt on and she runs but leaks coolant from the tank. Can't
> > find a tank anywhere up here. Anybody know of where one might be?  Looking
> > for the pressurized tank, not the filler tank.
> > Thanks,
> > John Kulina
> > 1990 Vanagon MV
> >
> > Sent from my iPhone
> >