I have just purchased a 2005 s type 2.5 and it is overheating and throwing coolant out through the expansion tank cap when hot. Has anybody else had this issue or can shed some light on the problem please. 

I think the first thing to do is check that the thermostat opens OK .????

Checked and there is no thermostat in it, so it's been an issue before 

hi

if its been taken out odds most of the usual stuff has been tried

first thing I'd check is head gaskets, either by compression test or sniff test, sniff test is the easiest option, done by most garages

head gaskets are common on these

once the heads gaskets are confirmed ok, would check water pump and radiator

cheers

Joe

Been told head gaskets are good and runs perfect 

It also looks like the water pump has been apart on it so think next is to check the radiator