2003 MG ZR coolant loss

common fault on K series engine is blown head gasket,check the water has`nt mixed with the oil,check the dipstick and filler cap do not have a creamy brown sludge in,if no obvious signs of water in oil then get a block test done,if this ok then check your cooling system for any leaks,check radiator,thermostat,water pump,inlet manifold gasket as these are all prone to leaks,is the cooling fan cutting in,as you might have a knackered coolant temp sesnor,refilling the aircon should`nt affect the cooling system unless something has been disturbed in the process,is it standard aircon or aftermarket fitment?

Thankyou for your reply 2145simon!

The air-con is standard fit.
As regards the oil contamination, there has been some creamy sludge under the oil filler cap since my gf bought the car 3 years ago.
It hasn't got any worse, so I am assuming that the head gasket hasn't failed quite yet. Obviously I could be totally wrong as I'm not a mechanic ;-)

I put some K-Seal in this morning and my gf drove to work (100 mile round trip) and it appears to have fixed the problem. Or rather, maybe delayed the hg blowing...
Tomorrow I'm gonna take your advice and check everything. Might as well get a new thermostat etc as they are cheap.

Once again, thanks for your advice!

glad to be of some help.if you need any help or advice then give me a shout,i worked for rover/mg so know them inside out

@ 2145simon have you got a contact number please or can you comment on my rover 25 loseing oil please many thanks