I have been trying to find the belt noise on my truck for the last 2 months. I replaced the belt and the old belt looked new. I replaced the idler pulley and it made no difference. I replaced the tensioner pulley and it chirps now so for sure the tensioner pulley bearings were bad. I spun the smog pump pulley and I can hear a low chirp like the shaft is worn or the bearing is wearing. However that's just part of the problem.

When you look at the tensioner pulley it sticks out about 3/8's of an inch from the other pulleys and its cocked so that the pulley sticks out more on the furthest part from the tensioner base. I have pulled it and looked at it and the bolt is straight, the tensioner base is factory and does not look damaged. I am thinking of using my grinder to try to adjust the base and the bolt to allow it to move in further. Any ideas from you guys. This chirping can be the belt because of the pulley or it can be the smog pump. What do you guys think?

 

No one can help me on this. Do smog pumps go out after time? Does the pulley alignment matter?

 

OK, here goes nothing. In my experience, noise is most often the belt moving across something that is stalling or increasing drag. Either by an increase in load or wear in a bearing. The fact that you got more noise replacing the tensioner would bear this out.

The idler on my tensioner arm is fatter/thicker than anything else & is smooth with no shoulder so it can "find" its alignment. Don't know what yours looks like.

I would NOT grind anything, especially if you are using all stock parts.

My opinion only, others may differ, your results may vary.

Good luck.

 

I agree with Scndsin.

Can you snap a pic of the misalignment?

Yes, smog/air pump can wear out. I have seen them lock up, burn the belt up. Some choose to ditch it and use a smaller belt, other use an idler pulley in its place, other tear it apart, gut it.

 

Check that the power steering pulley is flush with the pump flange. That can throw off the belt alignment as well, making the source of the sound hard to pinpoint.



A bad distributor bushing can also make an annoying chirp similar to a belt misalignment.

I wouldn't grind down the bracket...it can't be undone.

 

Thanks guys. I replaced the entire tensioner with a new high quality one and it lined up perfectly and no more noise. I was really dreading pulling that smog pump.