91 F150 302. Serp belt seems to squeal. Maybe a pulley. After a few minutes of it and I'm ready to put a shotgun under the hood and fire a few rounds for effect! It stops on occasion like somebody flipped a switch then later starts all over again. I have replaced the belt, and then it was quiet for about 30 min and started up again. I spray the belt with belt dressing and it stops instantly for a couple of min. Then away we go again. Any suggestions? I need my truck but I really can't stand the noise..... this has been going on for several years. I am ready to start replacing stuff out of desperation.

 

It sounds like the belt is slipping. Its either mis-aligned or the tensioner is too loose.
I'd check the tensioner first.

 

Seems to be very tight, minimal deflection. I will say the that waterpump pulley and the tensioner pulley are very "shiney" as if polished. But the tensioner pulley spins very freely. I took it off to see if the bearings seemed okay. When I try and spin the fan it makes a low whining noise.... but when I spray the belt dressing it goes away so I sort of ruled out the water pump and the tensioner pulley.

 

if you replaced the belt and the noise is still there, there is obviously a problem with a pulley. what u need to do is take the belt completely off and spin all of the pullies by hand exept the crank (if thats the problem the noise is the least of your worries) and listen very carefully cuz if it squeks when you spin it by had at 25 rpm or what ever when the motor is running at a 1000 it gonna make noise so listen carefully

 

After reading bunches of posts about this problem I rechecked the backside of the tensioner mech. There is supposed to be a "pin" that locks into a positioning hole on the mounting bracket. It controls belt tension/alignment I think. My pin is sheared off. I suppose this could cause the idler pulley to malfunction and cause belt squeal? I've priced one out at about $75. Anybody agree with this scenario?

 

it that were the case then using a wrench on the tensioner to add a bit more would also quiet the squeel. Sounds like an easy test to prove or disprove that theory.

 

"With the engine running, check drive belt tracking (the position of the drive belt on one of the grooveless pulleys, idlers or drive belt tensioner. If the edge of the drive belt rides beyond the edge of the pulley, noise and premature wear may result). If a drive belt tracking condition exists, visually check the drive belt tensioner for damage, especially the mounting pad surface. If the drive belt tensioner is not installed correctly with the locating pins in the locating holes, the mounting surface pad will be out of position. This will result in abnormal drive belt tension and chirp and squeal noises."

This is the portion of the Ford check list I found. After reviewing it, it says "pins". Mine only has one pin and pin hole. I suppose I'm talking about the same thing, but my model only has one. I guess I'll reinstall it and try adding more pressure (I hate losing fingers). If I don't post again I lost my typing digits.

 

I am not sure if it can be done but have you tried removing the bolt from the pully on the tensioner and putting some grease inside the hub/bearing area. Its a long shot but may help narrow the problem down.

 

Tried to get the bolt loose, but it beat me like a rag doll. Must be near welded on after all these years. I will say the pulley runs ok, and when spun it spins and spins and spins. Seems like it would have drag if the bearing were going. This item is the first thing I suspected. However, after spraying the belt with dressing and then the squeal stops right away I feel I have eliminated the bearing anyway. If I replace the whole unit it comes with the idler pulley? Or just the tensioner?

 

I think you can purchase either way.I have never replaced one in 250,000 miles.I know when you spray the belt the squeal stops.If a belt is slipping it should squeal. The belt dressing gives it some grip and stops the squeal for a little while.Try cleaning all of the glazing off the pullies and if possible scuff the belt with sandpaper.See what happens. No sense in changing parts until you can confirm what is needed.See if any thing is leaking onto the belt or pullies. I had a leak on the cooling system that went onto the belt and it squealed like crazy. Maybe a small oil leak or power steering pump seal.

 

Thanks, will try cleaning the pullies. No engine leaks or oil ect spilled in the area. I just got through reassembling the belt and positioned the tensioner by placing the spot where the pin used to be at the point of the hole and tightened it up. I found after cleaning off the road grime.... the "range" indicator for the first time. The pointer is not "in" range at all. Facing the engine the pointer is well to the right of the "range" box. The belt seems quite snug however. I would say within the 1/4 " range mentioned. Is it possible that the spring has become worn over time and now won't tighten properly? Like I said, the belt seems tight. I cranked it up and squeals abounded as usual. Sounds like its coming from the tensioner area. I'll sand the ribs a little tomorrow and see what happens.

 

How old is the belt? If it isnt in the range I would think the belt is stretched or since the pin is broken you may be off the target a little when reinstalled.The pin had broken on mine and when I installed I marked the tensioner with a marker to see if it would slip from the position it was bolted in. So far it hasnt moved and that was a few years ago.I will look at mine today and see if there is something there that I can shed light on.

 

I bought this belt about 5 months ago. Not many miles on it. I had ruled out stretch to the fact it's a serpentine belt. Do they stretch too? How many pins does your unit have? I have only one that is obvious. There are two other holes above and below the hole for the bolt that attaches the unit to the housing. The pin hole for the broken pin is at about 11 oclock (facing the engine) and offset to the left considerably.

To my way of thinking if I installed the tensioner with the "pin" at about 12-1 oclock (missing the obvious hole of course) this would put the tensioner in range. Of course if this pin were still present this would not be possible due to the tensioner not being flush to the mounting pad. So, is the tensioner worn, do I have the wrong belt, or am I a frustrated Chevy owner? Who knows. Maybe if I post the numbers off of the belt someone could confirm this is correct. I bought it at Autozone.... no brand on the belt. Can't remember what brand it was.

Also I declined to put more pressure on the tensioner while running. Way too close in there. cluck cluck cluck..........pwaaaak! I need my fingers.

Wish we could post pictures here. They say a picture is worth at least 32 words.

 

Remove or feed the pig

Moving the tensioner so that the pin of the mount is not in the whole will guarrentee it moves later on, if not misalign it immediately. The squeel won't go away and you'll break something. An airborne tensioner hurts.

You can post pictures here. Put it on a web server somewhere, and put the URL to the picture between the URL tags, or just above the white box where you type your post, you'll a tiny picture of a mountain with a sunset - click that and follow the prompts.

Something is misaligned. If it's really bad you could see it with your naked eyes, if not, you're not going to like the "hard way", which involves taking the fan(s) out and putting in a framing square. For a short time my crewcab ate belts faster than I could buy them, and I found that the alternator pulley was slightly bent, due to my skipping the air pump and the tensioner.

 

Agreed on the mounting dangers. Only tried that to see if I could influence the squeal one way or the other.

Great to know about the pictures. I suspect I should remove the fan and put the square to work. Other than that I'm at the point of just replacing the tensioner which now I realize has to be replaced due to the sheared pin anyway. So, I'll remove the fan and check the pullies and if they check out, I'll just put in a new tensioner. Then go from there. First, I'm gonna go take a picture of the tensioner and post it here so you guys can see what I'm talking about concerning the sheared pin.