Originally Posted by Uniblurb
Leave your belt tight for this and you may need to put a long screwdriver in-between the nuts/studs as a lever to hold it steady
I'd say 100% you'll need to do this, especially if the nuts haven't been broken loose in a while. I use a prybar in my left hand to hold the pulley steady, and a 13mm box-end wrench to break the nuts loose. There's a bit of a technique to getting onto those nuts with the fan blades in the way, and you just have to do it to work it out.