I'm about halfway into pressing a pulley onto a new power steering pump for my 96 Magnum engine. O'Reilly's and the like did not have an installer kit with the correct threads for the 96 PS pump shaft, so I had to use the "tool" that came with the pump.

The "tool" is a bolt, a square nut, a washer, a big thin white plastic washer thing that broke immediately, and a rubber o-ring that is sized to the bolt threads. The instructions made no mention of the o-ring so I have no idea what it's for.

After threading the nut onto the bolt and dropping the washer on, I threaded the bolt down the pump shaft and was able to get the setup to operate as intended - right until the pulley really squared up with the shaft. Then it just wanted to spin the bolt out through the nut.

I was able to get the pulley mostly pressed on the rest of the way (a couple ribs away from being square, about 0.5" of shaft showing on the back)) by looping the drive belt around the pulley and pressing down over the idler while turning the nut, but by then I wasn't able to hold the pulley firmly enough to continue to torque it down. I can't jam up the pulley through the bolt access holes or it will chip.

If the pulley isn't spinning under my improvised belt vise, I'm just backing the bolt out through the nut instead of continuing to spin the nut down the bolt to keep pressing the pulley on.

Is there another nuts-n-bolts way of pressing these things on? Am I supposed to put the o-ring at the very end of the bolt so it stays torqued at the bottom and doesn't just spin out or something?