Drive belt walking

Hi all,
I have a 97 Century and had to replace my drive belt because it was coming apart (the side of the belt closer to the engine was shredding itself and slapping around as it turned). I thought it was odd since it was replaced recently so i took it back to the auto store and had it replaced. Two days later, the same thing happened. I took a closer look at it and noticed the belt walked off the outer groove of the drive shaft pulley. So the belt was riding on the inside of the pulley and ripping it to shreds. I won't replace the belt again until i can determine the cause of the belt walking. So, i trimmed off the shredded parts of the belt and continue to drive the car without any problems, it is just not riding in the outside groove of the drive shaft pulley. Looking in the service manual, it doesn't give me any specific guidance for a walking belt, but it does give me several things to look at. Pulley alignment is one, but it doesn't show me how to properly check the alignment. Looking at them, they are aligned, but is their a specific way to ensure the pulleys are aligned? The manual also mentions the belt tensioner as a possible cause, but once again, it looks fine as well. Before i go crazy and start replacing a bunch of things that don't need it, could any of you help give me some tips on this issue?

Thanks,
Ray

Most times you can check pulley alignment with a metal straight edge like a yard stick. Check all them against each other in several angles. If they are in align then the straight edge will be flat aginst them all in every angle. Good Luck.

After checking it with the metal straight edge, it looks like the Crankshaft pulley (the book identifies it as a crankshaft balancer) is definately out farther than the A/C compressor pulley. What would cause it to come out like that? Should i just get a pulley install tool and push it back on? Or, is their something more serious i should be looking for. I can't imagine that it would be as simple as just pushing it back in.

They MUST all be in line. The one that is out of line with the others MUST be corrected. Something is most likely loose. Good Luck.

I've taken off the crankshaft balancer. I took note of the position it was in before removing it. Their was some silicone sealer in the channel where the shear pin goes. Shear pin was fine, the retaining bolt and washer were tight. I inspected the balancer for any sign of unusual wear and tear. Everything looks normal. I went to the parts store to see if they had a new one that i could compare, but they would have to special order it. So, i put the balancer back in. I couldn't get it in any farther than where it was when i took it out. I looked at the alignment again, and it is still off just as it was before. I think i will try to find another century, look at how the pulleys are aligned and compare.