are they easy to change think mine is funked no hot air on heating but after driving the car for 5-10 mins water in coolant bottle is still cold but radiator is hot so guessing water pump has failed.

cambelt is only around 8 months old can i use the same cambelt or am i best to change that again too?

new hcv was fitted around 5 months ago too heating was working a few days ago but the car was filled half with antifreeze and half water an i think it may have froze slightly and maybe broke the find on water pump.

 

It's not the pump or the engine would have cooked by now, but to answer the other question yes quite ok to re-use the timimg belt, a lot say no citing the reason being as it is retensioned it can get damaged!!
On the engine when it is running it constantly gets tensioned released on different areas of the engine, ie slack side and tight side!!
If the engine is getting up to temp but heater isn't, I'd be looking again at hcv and the heater pipes, unless heater is blocked/sludged up.
A 50/50 water/afreeze mis is fine, hasn't got cold enough to do any damage in this country.
tabetha

 

it takes ages for the coolant bottle to heat up as opposed to the rest of the colling system plus even after a 10-15 minute drive there is no pressure in the expansion tank i can just undo the filler cap no problem where as b4 it would have pissed out coolant due to the pressure.

 

The pressure and heat go hand in hand, ie hotter water = more pressure, check your thermostat first.
tabetha

 

im getting a correct temp reading inside the car on the clocks its just seems something isnt right and when the engine was fitted spring last year i have had some problems since and i dont trust any of the work that was carried out by the so called specialist who fitted the engine. so i always assume its worst things possible.

 

When I drove a astra that froze and snapped the shear pin(excellent idea ford, maybe you should use it!!) the gauge was in the red within 1/2 mile, due to no flow.
tabetha

 

sounds like a dodgy thermostat not opening up fully