It overflows because the fill tube is a slip fit into the tank.  It's
designed to not fill to the carpet level. Crawl underneath, remove (3)
6 mm bolts and you'll understand how it goes together.

Jim

All truth passes through three stages. First, it is ridiculed. Second,
it is violently opposed. Third, it is accepted as being self-evident.
--Arthur Schopenhauer

On Jan 5, 2013, at 12:35 PM, neil n wrote:

> The tank can crack.
>
> If memory serves, isn't the tank a 2 pc. design? Like the fill neck
> can be separated from the tank? Maybe a leak at that union?
>
> Maybe Bentley shows that detail?
>
> Maybe I've used too many "?'s"