Radiator losing water

[bkeo]

Ive got another problem with the mini now the radiator keeps loosing water in it and i dont have an idea whats causing it cause i thought it was the rad so i swapped it with another one and its still losing water somewhere .The head gasket and the thermostat were replaced recently and theres no water in the oil so i dont have a clue whats wrong with it. I put in rad well aswell just incase there was a leak somewhere.
Any ideas please

[city998]

Check your radiator cap. If the spring is too weak or the seal is gone, heat expansion will force water out the overflow. Are you losing a lot of water in a short time or does it go down gradually ove a number of days? How far is it dropping? Are you filling it to the top - if so I would expect the normal expansion to force some out the overflow.

You also need to check the hoses including the heater hoses in case there's a loose connection or a perished hose.

Good luck!

[The Marcos Graveyard]

A decent garage should be able to do a pressure test for you.