ALMOST no stupid questions... that was a good one. Don't be afraid to ask...

 

I'm with madhat, the only stupid question is the one you don't ask. then you are left with an assumption(AKA: lowest form of knowledge), or no clue at all.

 

Here is a follow up for those who may be interested.

First a quick summary of the history. The squeal started approximately 4,000 miles ago. Two belts had one edge get chewed up, one losing one rib and the other two ribs. Always the forward edge of the belt. The third belt was a heavy duty belt and was perfect for a few hundred miles before the noise started again and one edge of the belt showed signs of fraying. Checked everything repeatedly in an attempt to locate the source of the problem, but nothing showed up. Had to take a long trip, so took a couple of spare belts with me. Removed the belt often during the trip to check for out of line and free running pulleys. As usual, lost one rib of the belt. The squeal become continuous, but always went away after a while.

In desperation at one stop I bought some belt lubricant and gave the belt a good dose. The noise vanished and has not returned. Have now driven about a 1,000 miles since then with zero squealing. Still have one rib missing from the belt, but as everything is working just fine, am not going to install a new belt.

So, no conclusion as to the source of the noise or what is causing the belt to get chewed up. As long as there is no more noise and the belt does not lose any more ribs, am going to keep driving, but keep a really close eye on things.

Sorry, wish I could give you more info, but that is all I have for now.

 

I know you said you checked the fan pulley bearing and it spun freely by hand, try checking it with the fan and belt on. With the belt on grab the fan and check for any back and forth or up and down play. If you find any play you found the problem. There is a reason one rib is being chewed off and if you keep driving it without finding the problem you will earn yourself a catastrophic cascading failure instead of a $230 bearing replacement.

I see this happen often on larger trucks Stan, $230 is cheap compared to a new radiator and shroud, hoses, a/c lines, electrical lines and whatever else the fan will take out once the bearing fails.

Just my .02

 

Tim, have checked the fan for movement again and again with the belt on and with it off. It is solid. All the pulleys feel solid with zero play in any direction and spin smoothly.

I am very nervous about the possibility of catastrophic failure like you pointed out, but at the same time am reluctant to become a guessing parts changer. Used a stethoscope repeatedly everywhere I could and have not heard any bad sounds yet.

 

Have you tried a different manufacturers belt? Are these all the same manufacturer? Reson I ask is that while the p/n may stay the same, the material the belt is made of may have changed.
Grids makes it worse? I would think thats due to the intense load being put on the alternator, thus loading the belt more.
Not sure if you would find it by spinning them by hand due to there not being any load and not enough speed.
The A/C compressor could be deleted by using a non-ac truck belt.
I would probably focus on the pulleys that are ribbed (not the ones that run against the back of the belt)
As others have said, if you have to, paint the pulleys with some bright colored paint and look for rubs on the leading edge of the pulley.

 

Yes I did. The belt that is on there now is a Gates HD belt, a green color.

Have tried it with the A/C engaged and free and there is no difference in sound, so hopefully that eliminates the A/C.

When I get some time, will paint the pulleys.

 

Might want to take a look at that belt. Take if off and lay it on a flat table and make sure it's true. A buddy of mine had a similar issue with a brand new Dayco belt on his Superduty. Had a kink in it. Replaced with a Goodyear Gator belt and no more issues.

MikeyB

 

I'm sure you have checked for this already, but I'll throw it out there. I've seen sometimes when there is a misalignment problem that causes one side of a belt to lose a rib, with the engine stopped or idling the belt will appear to be sitting in its proper location on every pulley. Then, have someone rev up the engine while you are watching the belt. As the engine accelerates, the belt may hop over one groove on the misaligned pulley, and will hop back to its proper place as the engine comes back down to idle. Seen this a couple times, and it may just help you to narrow down the cause.

 

I really like the paint idea because it will wear off the pully that is eating the belt! Sure the lube quieted it, the squeal is coming from the belt being eaten, and the lube reduces the friction.

Paint and then please let us know what you find. Very interesting!

 

One thing I forgot to mention. Once a rib peeled off the belt, I made sure that the belt was positioned so that it was to the aft side of all the pulleys, thus ensuring that there was one groove of all the pulleys exposed on the forward side - the side where all the belts got damaged. In theory, if something on the forward edge of the belt was causing the squeal, then it would quit. It still squealed as usual. Only the belt lubricant stopped the noise.

MikeyB, I can see that, but this is belt #3 and if not brand #3, certainly brand #2.

 

Follow up.
Just thought I would update anybody that may be interested.
After I sprayed some belt lube on the belt, the noise vanished. Left the belt on with one rib missing, but kept a close eye on it. Have now driven many miles like that and there is no noise and the belt is not deteriorating any further. So as to what caused the original squeal and the tearing up of the belts is anybodies guess.
Will keep driving it like this for now and check it weekly.

 

I wonder if there is a rough spot, or something stuck to a pulley on that one ridge...

 

My truck has this god awful squeal. It only happens when I'm pulling the loader or if I'm in a hurry and hauling the mail. It seems to be the fan engaging and being too much load for the belt or my tensioner is weak. Haven't dug into it too much yet but if I push the clutch in and let the rpms drop and bring it back up slowly you hear the belt stop screaming and the fan start spinning up the rest of the way.

Mark

 

I had same issue, towing a camper cross country, awful squeel at first start when cold, would go away quick, crawled under at the ac compressor and saw the belt off track one rib toward motor, broke loose tensioner, moved belt and noise gone. 3 weeks later at a stop light sound like the tranny was exploding, pulled over and found one rib of the belt missing and wrapped around the fan, water pump and slapping the inside of the hood. Drove straight to parts store and got a new gates belt. 4 months later, same thing, new belt missing inside rib but this time it took out the crank trigger sensor and a few teeth on the plastic gear on the harmonic balancer. I replaced the idler pulley,or tensioner pulley, cant remember which one now, but was easy to see it was worn pretty bad on the inside, only when I could compare the old and new side by side. Didnt think it was bad at all until the comparison, it was like 18 bucks. Wish I would have done it before it took out the plastic crank trigger sensor and gear. Not cheap or fun.