My mom assumed ownership of my grandfathers truck after he passed away last year. It's a 1991 F150 XLT Lariat with a 300-6 and Auto. It has 100K and is in superb rust free condition.

Even when my grandfather drove it...it had belt noise to an extent. I never really paid too much attention to it then.

Anyhow...I've been doing some routine service work to it for her and noticed the belt chirping alot. It's worst on start up...and eventually goes away after 25 miles of driving, after the belt warms up from engine heat I assume. Until then however...it is ANNOYING!!!!!

The belt on it looked great and all the accessory pulleys spin very free and quiet. So I suspected the idler pulley on the tensioner. That's where the noise was obviously coming from. Its bearings seemed stiff and dry...so I replaced it. Helped for about 10 minutes.

Next I replaced the tensioner itself, which came with a new pulley as well. Helped for an afternoon. The next day it was back as bad as ever.

Next I replaced the belt with a Dayco...as Gatorbacks (which I usually use) are NLA at any autoparts store (Napa, Zone, Advance, Orielly). The Goodyear shop didn't have one in stock and acted like I was asking for a sacred stone anyhow. All they wanna sell is tires.

This helped for a full day. Then it was back as bad as ever again.

I noticed that at idle the squeak occurs when the Dayco printing on the belt passes the tensioner pulley. So I scuffed the lettering off with scotchbrite...and scuff finished the pulley. The plastic pulley (Dayco) was shiny and slick originally.

This helped for a day and it was very silent now. I really thought this would do the trick...until tonight it started squeaking again just as it always does.

It's so annoying with this noise. Its terrible sounding and irritates the crud outta me that I can't solve it. I've never had this much trouble with a belt. In fact...I've never had a belt squealing issue on any of my 15 different vehicles...even ones with ruined idler pulleys and junk alternators.

I suspect the plastic pulley is part of the problem. Or else its out of round. Usually I've only ever had steel pulleys...whether it be on my Fords or GMs.

Does anybody make a steel replacement tensioner pulley?

 

You sure its a Dayco Poly-rib belt?

I had the Same problem and it was due to an inferior belt, new Dayco poly rib, and it's done squeaking!

 

I had this same problem on both my F250, Explorer, and my friends C-10...I used WD-40 and sprayed the pulleys where the belt goes, and I sprayed some on the belt. Went away almost instantly for all 3. Idk if it's right I do that, but it works, and I've never had a problem. You will however get a little WD-40 everywhere.

 

Maybe the problem isn't with the belt or the tensioner pulley. I've had alternators that made noise only when there was tension on the pulley. Take the belt off, spin the alternator, and no noise. Put the belt back on, start the vehicle and the noise comes back. This is one of the things I don't like about having just one belt on a vehicle. It makes it difficult to determine where noises are coming from. Back in the days of multiple V-belts, a fella could use a process of elimination to figure out what is going on.

 

As far as I know its a Dayco belt. I bought it at AutoZone...the cardboard said Dayco...and the belt had the Dayco logo, numbers, poly-rib name printed on the rubber in blue/white. Until I rubbed it off. The pulley I bought and the second pulley that came on the new tensioner...both had Dayco on them. And NTN-Canada bearings.

I actually took an electric motor and hooked up a typical V-belt to all the accessories individually. I held the motor while I spun the pulleys at speed. It was kinda trickey to do...but it worked. Everything seemed quiet under that circumstance. Very quiet actually.

I'm sure its the tensioner/pulley. The noise is so obvious right there...and the squeak was obvious when the Dayco printed area on the belt passed that pulley. It was timed perfectly.

I'm going to drill wire wheel all the pulleys...in line with the ribs to clean down in them. I cleaned the water pump pulley with denatured alcohol real good and scotchbrite.

I will say that today...it started up and drove with no noise except for a tiny bit on down the road. Then it went away again for the rest of the evening.

Having always purchased GatorBack belts for my own vehicles (the only one that won't chirp on shutting down a Cummins engine)...the Gatorbacks sure feel nice and soft, rubbery...like a tire. The Napa and Dayco belts feel "hard" and "plastic like". Slick too. Gators make tight bends with ease...while other brands seem to be much stiffer. Who knows.

 

Dayco belts always squeaked on mine, I went thru 3 of 'em before I got a Goodyear Gatorback, that fixed it for good. Advance and Autozone don't carry that anymore so I got mine on rockauto.com.

 

My '97 5.8 250HD has the same issue pretty bad. When I let it warm up in the morning it wakes up the neighbors, LOL. I noticed that it's worse on a humid or foggy morning, or if it rained the night before. I always suspected it was because I got anti-freeze (sticky) on the belt & pullies at one time (blown hose). I should clean all the pulleys with alcohol and install a new belt and see if it fixes it.