Smoking Lucida - Part Deux!

[Taffy]

Hi.

Bought a new engine head (£450 from Corry Heads) and had it fitted (£600) 6 miles down the road the coolant in the overflow was bubbling like a kettle and back to the garage it went. The mechanic has taken the head off and tested it, it's fine. He's changed the thermostat and put a heavy duty gasket on, and I'm currently waiting for the news. If it's still boiling water, does anyone know why? I fear the engine block itself may be cracked, is this likely? Any advice gratefully received.

(These buses are lovely when they're going, but a !Removed! when they go wrong!)