I'd keep an eye on that DM, sounds to me it could be the system is pressurising and could be the signs of a failing head gasket.
Epic, if your losing water and there's no sign of a leak, check the dipstick for water in your oil, just to be safe.
I'll bet you both have failing head gaskets, TD5s don't like over heating, so I would get things checked right away, if you overheat them to often, the head will fail.
Baz.

