Been chasing this problem on and off for months.. It comes and goes, I think I'll have it solved and then it comes back.

• Replaced smog pump, new pump was 'suppose' to make the sound for 300 miles, it gradually went away and I thought it was solved.
• Came back a few weeks later.. replaced the belt .. it went away immediately but gradually came back
• thought my new balancer wasn't tightened all the way and my crank pulley wasn't in alignment, tightened it better, it went away for about a month and I was sure I had solved it.
• Changed water pump/timing chain.. when I bolted everything back up, it came back.
• Tried to tighten balancer (as i thought that solved before), no go. Used an installer, torqued properly, still making the sound.
• Soaked my tensioner in WD40 overnight, it went away for a while.. thought I had it solved
• Bronco sat for a couple of days and it came back when I restarted it.
• Noticed a squeeling alternator, repacked and cleaned the bearings, it's smooth and quiet now but the noise is still there (so it was noisy, but not the main cause)

I'm at a loss, I can't figure out where it's coming from. I put a new idler pulley on, the mark is in the 'range' area on my tensioner.
The sound isn't there with my belt off so it's definitely an accessory.

Screeching Pulley - YouTube
tried to single in on accessories, maybe someone here will notice if one is louder than the other? it's hard to tell.. tried a mechanics stethescope and learned absolutely nothing. Everything through the stethescope is just making a rolling bearing sound.

 

Same issue I figured out on our 99 Taurus.

I did pretty much everything you listed on this car.

I ended up changing the tensioner it self.

It looked like it was in range too.

Runs real quiet now, just like new.

What belt are you using. I put a cheap one on vs. a Motorcraft one.

Everyone else swears by GY Gatorbacks.

 

Change the tension pulley.

 

It honestly sounds like the tensioner pulley. There is no roller bearing in it. Its just a sleeve in the pulley that slips over the bolt/shaft so there isn't much you can do to alleviate the problem once the sleeve has worn down enough to allow the slightest mis-alignment (squeal). I've seen brand new aftermarket ones do this due to a lack of lubrication during assembly... (manufacturer assembly, not end user). As a result, I remove the pulley and graphite the heck out of the shaft and the sleeve in the pulley before I put any belt tension on one that I replace. Remember that the bolt that holds the pulley to the tensioner is right-hand threaded (left-tight, right-loose).

 

This is a big NO - NO. Don't ever use WD40 or any of that kind of oil in any pulley or bearing (or any part that uses grease), those oils displace the grease and fade away very fast, leaving the part without lubrication. My money is either on the tensioner or in the idler pulley. take the belt off and start turning each pulley, see if any offers resistance, or makes noise, or has any play, that will probably be the cause.

 

Actually there IS a roller bearing in the idler pully, or at least the ones I have do. Twice I have pressed the sealed roller bearing out of the plastic pully and replaced it with a new bearing. Once on one of my broncos and once on my F-150. Mine wasn't squeeling though, it was making a growling noise.

 

Agree, need new tensioner. Spring just plain gets weak.

 

Our Taurus did not have enough tension on the
Belt, and causing the undetectable noise.

Cheap fix after throwing parts at it that is.

 

I didn't soak the pulley itself, the tensioner pulley is actually brand new. The one on there before was new'ish but was a bit too small, the new one is the 3'' which was stock on this engine combo. (plus I have a saginaw pump and 3g alt)

and the wd40 for the tensioner was just to remove rust/corrosion from the spring to reduce tension and to clean it up a bit, I filled with grease and it didn't make a difference, so I cleaned it out again with WD40 (to remove grease/rust). Then used an engine cleaner (to get rid of the wd40) and was just trying it completely clean in the video.
I expected the sound to change somewhat after that, just at least so I could troubleshoot the problem.

One more thing that has me iffy about running out and spending $75 on a tensioner. When I put a wrench on the bolt and tried to push down to tighten while the motor was running, I got absolutely no change in sound. However, it doesn't take much force by hand to push the tensioner down after I shut my motor off.

The belt is a dayco, it still looks brand new and isn't glazed or anything.

 

NEVER, NEVER handle a moving belt or pulley or you will end up with the nickname Stubby.
Here is a list of pulleys for a lot less than the $75 you mention;
Advance Auto Parts: Search Results for tension pulley

The complete assembly is currently $45
Dayco 200-89236 - Dayco No Slack Automatic Belt Tensioners - Overview - SummitRacing.com
Buy Dayco No Slack Automatic Belt Tensioner, Light Duty 89236 at Advance Auto Parts

 

You can change pullys all day long with no results. The tensioner assembly itself is most likely the problem. Can't say 100% sure, internet trouble shooting is not an exact science.

 

err, there was some confusion. I meant I already changed the pulley (which was 15), that's not the problem.

Seperately, I dont like the idea of throwing $75 into the tensioner without knowing for sure. I have seen people say tensioners fix the problem, but I have changed sooo many parts chasing this that I'm just about sick of it. (rebuilt alternator twice, changed smog pump, two idler pulleys, new belt, flushed power steering). .. honestly, my waterpump/timing set change were related to this problem as well, I probably would have waited on those items if I hadn't been fighting this (though I'm glad i didnt). Thought leaking coolant was causing the noise.

I hate problems like this.. if I can't troubleshoot it, I can't fix it and I end up replacing good parts to try and find it. I can't really afford that.. I'm still trying to get my truck regeared, get a good plate bumper made so I can mount my winch, etc.

 

and you guys notice how it sounds like the sound is coming from EVERYWHERE? it's just as bad in person.

 

It might be a long shot, but take out the alternator and inspect the rear bearing. This happened to me earlier this year: https://www.ford-trucks.com/forums/1...l#post10385665

 

The rear bearing in the alternator was in good shape but dirty and making noise when I pulled it, I cleaned it and cleaned it and cleaned it then put grease in and it went silent, felt fine. After seeing those pictures I think I'll pull it one more time and see if maybe I didn't do the job. I had repacked the bearing when my front bearings dried up but didn't clean it, this last time you could feel that it had picked up a lot of crushed carbon, but I got to it before the ***** took any damage.
I wish you could buy the rear bearings seperate, no local store has them.

also, a bit more testing, when I tighten the tensioner by hand with a wrench.. like if I push it down when the motor is off, when I restart it stays at that point and doesn't freely move back if that makes any sense? I know it use to move more freely than it does now.
In other words, if I let the tensioner rest by itself it moves to about the top of the "Range" brackets, if I push it down it moves closer to the middle and stays there without bouncing back up. I don't think a tensioner is suppose to do that. It will stay at that point while the motor is running.

Also! When I got the truck it was running the idler 3.5'' pulley, after the 3G and Saginaw swap, I put in a smaller no-AC pulley (2.5'' or 2.75''). The 3.5'' was tight without the swap, hard to get the belt on, after the swap it was impossible. My new belt was a tad looser than my old one apparently, the 2.5'' Pulley wasn't enough and it took the 3'' to put it towards the middle of the "Range" brackets on the tensioner, the old 2.5'' has it towards the low end of the "Range" brackets, the 'original' 3.5'' had it well above the range brackets, but I haven't run it with the 3.5'' for almost a year.