I have a 2003 Chevrolet Silverado with a 5.3L engine in which I am replacing the alternator. But now I cannot get the belt to go back on for some reason. I am turning the tensioner release pulley all the way to release the tension but the belt does not seem to have enough slack to go over the alternator pulley. The new alternator looks the same as the old one and I even went back to the auto store to make sure they sold me the right alternator. I looked at youtube videos and they show that I am doing it correctly. But something is wrong. Anyone have any suggestions?

 

Are you using the same belt that was on there with the old alternator? Is the pulley on the new alternator the same size as the old one? If you answer yes to these then the belt is not on the pulleys correctly. Check to make sure the belt is in the grooves all the way and not partially on or off.

 

Also make sure that you are routing the belt correctly on all the pulleys.

 

Attached 5.3 routing

Start at the crank, then get the remaining pulleys, for ease of install get all pulleys done but leave the belt ABOVE the Idler pulley. Once you get the tensioner compressed simply slip the remaining belt under the idler and release tension on the tensioner pulley and you are done...

 

I inspected the old belt and still looks good so I am re-using it. I never took it off the other pulleys. I made sure the belt was in the groove of the pulleys and it was. I did not tried putting the belt on all the pulleys and then put it on the tensioner pulley last. One thing I did notice when I look at it again today was the tensioner was a little loose. I took the pulley itself off the bracket and noticed the bolt was stripped. Maybe when I was turning the bolt to the right to release tension on the belt it never went all the way over because of the stripped bolt. I will pick up a new tensioner pulley assembly tomorrow and then try it again. Its crazy because I know it released enough tension to get the belt off to start with.