You need to remove the radiator, if for nothing else to give you room to swing the hammer you need to install the damper, unless of course someone drilled and tapped the crank. I'm pretty sre there is radiator interference with the damper as well, I know I had to remove my radiator to remove the damper. But don't worry it is very easy to drain and remove the radiator. Use the speedi-sleeve, they are readily available, and work like a dream. We use them at work a lot, saves a lot of money on machine work/replacement.
