Changing the Serpentine belt is something that I do every 100k miles. I figured that is about 5 years for one of our cars and it is when rubber starts to break down and stretch due to high amounts of use. The last thing that I want is to be broken down on the side of the road because I was too lazy to change out a $30 belt. Since my Envoy now has 210k miles on it, it is due to have the Serpentine Belt replaced for the second time. Here’s how you do it…
Purchase a Serpentine Belt
This is a really simple job, the only tool that you need is a ½ inch ratchet or breaker bar.
Find the tensioner pulley located underneath the big pulley on the passenger side of the engine. This is a Vortec 4.2 liter in line six and this process should be the same for all trucks with this motor, the Trail Blazer, Envoy, and Bravada. I don’t think the Saab came with the 4.2 option, but if it did this would apply to that as well.
There is a place on the tensioner pulley that you can put the ratchet into and loosen the tension on the pulley allowing you to get the belt off easily. Insert the ratchet into the spot for it, have it set for tighten, push down (or pull over, whatever you find easiest…) and loosen the pulley.
While you have the tensioner pulley pushed down, just slide the belt off. Once it is off, you can just pull it up and out of the engine compartment. There is nothing in the way, since the belt routes over the top of the fan clutch.
If you forgot how to route the belt when you took it off, or you just did not look, don’t worry. GM did us a favor and put the routing of the Serpentine Belt on the fan shroud! Just follow the directions listed and put the belt back on. I found it easiest to get the belt around the crank pulley first, then up and over the fan pulley, followed by the pulley on the bottom right, around the idler pulley and then the alternator. Once I had the belt around the alternator, I positioned the belt properly around the tensioner pulley and got it close to the big pulley on the top left.
Once I had the Serpentine Belt routed and close to the big pulley, I pushed down on the ratchet and pulled the belt up and around the big pulley on the top left. This took a little doing, with the new belt being a lot tighter than the old one, you just need to get the tensioner loosened as much as it will go and the belt will slide over that pulley. I just kept at it and eventually got it to slide up and over. It was pretty much just a case of me not pushing enough on the tensioner pulley, once I had all the tension out of it, I was able to get it on. Persistence pays off!