I just went through this last weekend ('04 at 50K). The pulley slipped back literally an inch toward the block. Let me share my experience with you. First, look at the project referenced above. Pretty good picks. Go to Autozone and get the fan clutch removal tool and the harmonic balancer puller. Autozone didn't have one, so I went to Napa and bought one of the fan clutch tools that has two hooks on it to hold two bolts. Take off intake hose, fan, shroud, and belt per the project.
Next I used the proper bolts from the harmonic balancer puller in the harmonic balancer (without the puller tool inself), and used the tool from NAPA to hold the bolt heads while I started backing out the center bolt (19 mm). I didn't unscrew it all the way, so there would be some threads engaged to start pulling with the puller.
For me, the bolts in the harmonic balancer puller from autozone were not long enough to go through the puller and reach the holes in the back of the balancer. I couldn't find the bolts locally, so I bought a 2' piece of 1/4-20 threaded rod, some washers, and some nuts. I cut the rod to length (2 pcs), long enough to go through the puller, the pulley, and through the back. You can reach the back side of the balancer to put nuts on the end of the rods. then I used the puller bolt to start pulling. Once I felt the puller tighted up (as the balancer bottomed against the partially threaded bolt), I stopped and took the bolt the rest of the way out. The balancer was still too tight to come off by hand, so I wrapped a long skinny bolt with tape to not damage threads, and stuck it in the center hole until it bottomed out. This gave the puller something to push on so i could keep using the puller.
Finally the balancer popped off. The Ford replacement I was given is a different design, and the inside is essentially hollow. Plus they recommend replacing center bolt. The harmonic balancer installer that autozone had won't work with the ST, so I lubed up the new balancer, lined up the key slot, and pushed it on the best I could. I couldn't push it on by hand far enough to get the bolt started, so I got a buddy to hold the bottom of a 2X4 on the ground while I hit it above the radiator with a hammer. Just hold the 2X4 so that even as possible pressure is applied to the face of the balancer. After a few wacks, the balancer was far enough up the tapered shaft that I was able to get the bolt started. Then I put the puller bolts in the balancers puller holes, and once again used the tool from NAPA to keep the pulley from turning while I tightened the center bolt. I just kept cranking until I was able to torque it at 85 ft lbs.
As I noted above, the new design is hollow inside, whereas the original was more solid, with just holes for the center bolt and the puller bolts. I found after I finished that as I was tightening the center bolt and holding the puller bolts with the NAPA tool, the balancer puller bolts were actually bending and twisting. When I tried to straighten it up to back it out, the tip broke off. Hope it doesn't create a problem down the road, I just left the broken piece in the hole. It's a light enough weight bolt and it's close to the center, so no balance issues should occur. If the balancer had been the same design as what I took off, the bolts would have been able to rest on the sides of the deep holes and I wouldn't have had that problem.
Put everything back together and, after a quick jumpstart, Got it running smooth as ever.
I wish mine had been as easy as Todd Z says it is, but it wasn't. Hopefully yours will be. Hope the above writeup helps. Any specific questions, ask here or send me an email.
