Recently I have been experiencing a serpentine belt squeal in my Bronco. After searching all over various sites, I read from a lot of sources saying to remove the belt, check/replace and clean the pulleys, and replace the old belt with a new one. So I did just that. I cleaned the hell out of the pulleys with steel wool and brake cleaner, replaced the idler pulley, and put on a new belt. The squeal went away until the temperature dropped - then it came back. Whenever the temperature is around 35 or below, the squealing returns. It is constant while the engine is at idle and gets worse under acceleration. Any help with further diagnostics/words of advice would be appreciated! I hate to take it to the dealership for something that should (hopefully) be a simple fix.

 

Did you replace the tensioner? if not do that.

 

When it's cold, pull the belt and spin all the pulleys by hand. You should be able to feel the bad one.

 

What are the chances that the alternator pulley is bad? The squeal is coming from that side so it must either be that or the tensioner. I'll have to take things apart again and do a double check of all the pulleys. I'm just trying to make this fix as easy and cheap as possible, as I'm running on a college student budget...

 

Tensioners loose strength over time and that rig is nearly 20 years old. Change the tensioner if you havent!

 

Alright I'll have to try that next, if that doesn't fix it then we may be looking at a new alternator. Hopefully the former option fixes things rather than the latter!

 

If the alternator is bad, you will definitely feel it when you try to spin its pulley.

 

I ordered a new tensioner last night so when I get that installed I'll report back with the good (hopefully) or bad news.

 

Ok, so I finally found the time to replace the tensioner pulley. It is still squealing...not as bad, but it is still easily heard from inside the cab with music on, etc. So this must narrow it down to the alternator pulley, correct? Anyone have suggestions on fixing this problem without replacing the whole alternator? I just paid almost a grand to get my transfer case fixed so money is definitely an issue at the moment.

 

See below:

 

I tried all those things mentioned when I was replacing the tensioner and the pulley felt fine. No squealing and it had no play to it either.

 

The pulley won't squeal or have play in it when you turn it by hand - it will most likely have some noticeable drag and/or roughness, which will cause the BELT to slip and squeal.

 

Alright that makes more sense..
Well thanks for the help!