I'm Chris, Thanks for allowing me to help you here on Just Answer.
You must remove the belt. then remove the bolt holding the pulley on. Now use a jaw puller or harmonic balancer puller and press/pull the balancer off. If the radiator is limiting your access it must be removed. Once the pulley is off you can replace the front seal which i assume your doing here.
I am having a terrible time trying to remove the woodruff key so we can remove the harmonic balancer so that we can proceed. if you know of sites that would have pictures of this, that would be very beneficial. or maybe you can go step by step to make sure im doing this properly.
east coast irrigation