right got a taxi in at work at the moment,
before xmas then the waterpump decided to give up and in turn ended up boiling the engine god knows how many times, the driver just kept topping up the water continuosly, we replaced water pump, timing belt and thermostat, fitted new head gasket had the head skimmed and pressure tested.
its been fine for around 20.000 miles but now all of a sudden its pressurising all the water again blowing it out the expansion tank. ive replaced the thermostat again incase that was faulty, the water pump is definately working as its pumping the water good style..... anyone got any thoughts??

 

How does a taxi do 20,000 miles since xmas on Shetland?

If it's blowing out coolant, it's gotta be either :

Head gasket
Cracked/warped head
Cracked/warped block

Or not circulating for whatever reason (air lock,water pump,blocked rad/pipes etc)

What engine is it, 2.0/2.2 DW10/12 or 1.8 Lynx/Endura?

 

Hah tell me about it. There run 24/7 and normally by idiots driving them. It's a 1.8 tdci mate, can't really understand how an airlock would of appeared from nowhere, but my gut feeling is a cracked head or block