I looked at all of the different forums and didn't find one specific to "belts" or "engine accessories", so I decided to give posting about my serpentine belt in here a shot.

1994 F150 XLT 5.0L Auto w/ Air -- 168k Miles

Okay, not sure where to begin other than saying that I'm totally lost and know of nothing else to do...

This all started back in the Spring-- a slight "squeak, squeak, squeak" at idle speed. I searched the internet thoroughly, checked the pulleys/accessory bearings by free-spinning them, etc. and couldn't find anything matching the noise I heard. The only thing that really turned up on the net was possibly the smog pump. It did make a slight noise when turned by hand, but not the squeak, squeak I was hearing... However, I decided to replace it.

The new pump had a sticker that said to give the pump 500 miles of run-time to "seat" the new bearing. It did squeak for a short time, but went away-- no more noise. Then, I bought a Miata to drive back and forth to work in and the truck started sitting. When I'd go to drive it every two weeks or so, the "squeak, squeak, squeak" was back, only a little louder. I replaced the idler and the tensioner pulley to no avail. I took them back to the parts store and swapped them for a new belt. It's a Duralast from Auto Zone, which was the best they had. The truck had a Gatorback on it that's been there the seven years and 40k+ miles I've had the truck. The only reason I replaced it is because I thought it might be the culprit.

Well, it wasn't... It's even worse now-- it's a "squeal, squeal, squeal".

I researched the net tonight and read about cleaning the pulleys with a wool pad and brake cleaner and decided to give that a try. I even roughed up the belt a little and it's even worse now... It's a constant shrill-squeal the whole time the truck is running. I don't have any belt dressing, but I decided to see if WD-40 would do anything at all... Nope.

I put the worn Gatorback on and it's a little better. I then decided to check the tensioner. I started the truck and put pressure on the tensioner, again to no avail.

I've been coming back and forth to the computer, tying this up over the last hour or so. Between the time I started typing and now, I've tried one more thing- soaping the Gatorback belt.

I started the truck to the now-usual shrill squeal and immediately soaped the outside of the belt with the only bar soap I have; Irish Spring. Lol. It turned the belt green and quietened some, but wore off quickly and began to not be any good at all, even while still holding the bar to it. I then had the bright idea to soap the inside of the belt... WOW! Instant relief!!

I let the belt eat roughly 1/2 of a bar and stopped. It's like new again!

Although, I know this is only temporary... I have come to you guys to see if any of you have run into this and what might've fixed it. I know that a new Gatorback will be on its way soon, but what else? I cleaned all of the pulleys except for the crank.

HELP!!!

 

How old is the belt? If it's glazed and has hairline cracks ... I'd slap a new one in there. Shouldn't take more than 5 minutes. Keep the old one as a spare.

BTW, I'm a firm believer in NAPA for parts. That's just me but after crappy starters and such from the "low cost guys", what can I say?

 

Thanks for your response, tomandbeth.

The belt that was on the truck when I got it seven years and 40k+ miles ago was a Gatorback. It showed no signs of cracking, glazing, etc-- I just decided to replace it because I couldn't find the culprit to the squeak.

But, now it's back on and Auto Zone is getting their Duralast belt back...

 

I have had a similar problem in a 5.8 and did much of what you have to try and remedy it but with no luck. The only thing I can think of is that a pulley may be slightly out of line with the others.
As I don't drive the truck that often anymore I have resorted to applying chalk to the belt when it begins to squeal, as silly as that sounds. That seems to last a day or so.
Sorry I don't have a better answer.

 

Is the ac compressor good
The bearings could be hanging up giving that squeak
Just a thought

 

Never use WD-40, it can harm seals and it doesn't last.

Gatorbacks are great pieces, and I would suggest them next to Motorcraft.

The more foreign materials you start putting on your belt is stuff you need to clean off later when you install your new belt. You may have to clean all the pulleys later to keep the contamination off your new belt.

Most times the idler pulley and the tensioner assembly can cause the elusive
Squeak.

In some cases even if the tension assembly reads in the "good" range, it not
Be putting enough tension on the belt.

Is the tensioner assembly original?

All of the above is "been there done that" so you really need to start with clean parts.

 

Thanks for your response, Rebuild101.


As far as I know, the compressor is good. When free-spinning the pulley, it makes no noise, and it doesn't make any more or less noise when the compressor is engaged and the truck is running.

When I put the bar of soap to the grooved side of the belt, the squeal immediately went away.


IMHO, one of the grooved pulleys, the belt, the tensioner, or a combination of any of the three is the culprit.


The WD-40, I know, wasn't smart... It was just something I gave a squirt at to see if it administered any relief.

I will be ordering a new Gatorback or Motorcraft belt soon... Would you say that the Motorcraft is superior or equal?

When cleaning the pulleys, do you scrub them to a brilliant shine or just scuff the surface with a brush?

I had replaced both the idler and tensioner pulley to no avail-- the squeak, now squeal, remained.

To my knowledge, the tensioner is the original, however... When I applied tightening force to it while the truck was running, the squeal remained. It did let up slightly, but it didn't correct the problem. Was this test adequate, or should I just order a new tensioner/pulley assembly? I also noticed that if I put downward pressure with my hand on the belt between the A/C compressor and the idler, I could take slack in the belt. Is that normal, or should there be quite a bit of resistance?

Thanks again everyone!

 

Oops... I skipped you!

Thanks for your response.

What type of chalk are you describing?

I would be happy with the soap trick if it only had to be applied every week or so. Time will tell, as I haven't even had the truck above an idle since I did the application.

Thanks again!

 

The only squeaks/squeals I've ever dealt with on my truck was from grains of sand in the belt grooves and bad idler and tensioner bearings. Or when I spill or splash water on it, though that is quite temporary.

Good luck.

 

Thanks for your response, GoinBoarding.

I drove the truck about 40 miles tonight, and the squeak never returned until I took it to the car wash. Instead of the automatic wash, I used the "wand" and gave the truck a bath, making sure to spray extra water into the grill to simulate rain spray. Only after that did a slight squeak make itself known, which was nothing compared to the squeal from before.

I'm going to put a little more soap on the belt in the morning and just see how long it will last all together. I observed the Gatorback belt that I have back on the truck, and I didn't notice any rotting or splitting. So, I'm going to live with that belt for a while longer. When I do decide to change it in the future, it will be accompanied by a new tensioner and a thorough pulley cleaning.

 

Try the new Gatorback with a good pulley cleaning before investing 70.00 or so for the new tensioner assembly.

Keep us posted.

 

Will do.

Thanks again for your assistance!

 

I spray Armor all or son of a gun On the belt stops squeak immediately

 

Note that the thread is over five years old, the OP has probably resolved his belt squeal issue or given up by now. But what you are recommending only lubricates the belt, making it easier to slip and simply eliminating the noise. It doesn't actually fix the issue and is comparable to turning the radio up to solve a rod knock.

 

4.9 motor here,

I changed the belt , and auto tensioner on my motor,

also changed the clutch fan...

I let the truck warm up until the RPMS drop, always, takes maybe a minute.

it squeaks sometimes, but not as bad as it did. I think they all do that to some degree.

I have used belt dressings before, in my experience, the belt dressing makes the squeal louder until it wears off.