I just replaced my belt on my 96 blazer. My question is when i put the new belt on i notice the idler pulley shakes a bit. Its not making any sounds or anything. Could it be because it is adjusting to the new belt.

 

Idler pulley shakes.....not sure what you mean by this....is it just the pulley itself has movement or is the entire assembly (pulley, bracket) moving?
I will assume you mean the pulley itself, which is probably a worn-out bearing. Suggest replacing at least the bearing or you could get the entire assembly. I do not think it is very expensive.
You really do not want the bearing to seize or come apart so the pulley falls off when you are driving.....spinning hunk of metal could take out other parts.

While you are there, check the harmonic balancer condition.....the rubber between the inner and outer rings. Another hunk of spinning metal that you do not want coming apart when driving.

 

I have a video of what it is doing. I cant seem to upload it here. I drove it this morning fine. It doesn't seem to be making any noise. I might just replace it anyways.

 

It simple and about $30 to replace the idler pulley and the pulley on the tensioner. I usually get from Advance auto as I use the 15-25% online discount and the training store and warehouse is about 2 miles from my house.

Edit it's an idle pulley not puller

 

Its the wrong pulley, its the automatic belt tensioner is what is wiggling.

 

I did reference both the idler pulley and the pulley on the belt tensioner.
Given that is assembly moving in and out from say a broken spring or is the whole assembly wiggling because of a loose bolt?

Or is the bearing bad in the pulley and you can take off the tensioner and replace it.

 

If it's moving slightly in the adjustment direction, it's fine. If it's wobbling on its axis, the bearing is probably shot. Usually, a bad bearing will make noise.

 

The older style of idler pulleys were just a sheetmetal pressed pulley where the bearing is pressed in directly to the inner sleeve of the pulley. If not properly pressed in it can wobble while the bearing is still good.

Be careful if the whole tensioner assemble is loose. The bolt may be a left thread on some model years. If forced to the wrong side it brakes the thread in the aluminium support and may get loose as you can no longer tighten it properly.

I had one pulley wobble on me and it was because by pushing the belt over it, i had slightly dislodged the pulley on the bearing. Taken the pulley out and pressed in properly on a bench press, fine ever since. (about 15 years now)

 

This sounds just about what is going on with mine. The only problem is i don't have a bench press. I was thinking about just getting new one. Do these pulleys have to be torqued or is it just as simple as screw on kind of thing.

 

In the past, they always sold the serp. belt and the belt tensioner separately. You bought those new pulleys when needed. Now the trend is to sell a 'Kit' with the new serp. belt, the belt tensioner, and the idler pulley together. I think this is a good approach as it encourages you to replace the idler pulley and the tensioner before something bad lets go on a dark and desolate road. Rock Auto sells a Dayco 3 piece kit with a belt, pulley, and tensioner for $70.00. The 3 items you get are: the serp. belt, the idler pulley, and the auto belt tensioner. Take a look.


https://www.rockauto.com/en/moreinfo...sn=526&jsn=526