Noisy radiator

Assuming this is a pressed steel rad mounted on wall brackets, one possibility is that the noise is caused by movement and metal-to-metal contact between the mounting lugs on the back of the radiator and the brackets that are screwed to the wall. Plastic spacers are often supplied to prevent metal-to metal contact but these are not always fitted. If that is the cause you might get away with spraying WD40 - if that works it more or less confirms the problem. Otherwise you need to drain the radiator and tilt it forward/remove and fit plastic spacers or similar to prevent the metals touching during movement.