Serpentine Belt Chirp

PABowhunter · Nov 12, 2014

About a year ago my serpentine belt started chirping. Constant chirp, couldn't get it to go away. Checked all the pulleys and they seemed to be good. Was out of town and went to Advance Auto and got the most expensive one they had. Belt came with a 3 year warranty. Chirp went away immediately.

Fast forward 6 or so months and the belt is chirping again. Checked all the pulleys again and didn't find anything obvious. Got a free replacement from Advance and chirp is gone.

Fast forward another 6 months (this past week), and the belt is chirping again.

Keep in mind, this is all with low miles on the truck. I think I might have put on 5,000 miles so far this year.

Is the problem just a crappy belt? Or do I need to take a closer look at my pulley system? I don't mind the sound of an old 7.3 with single shot injectors, but a noisy belt drives me crazy.

DEEZUZ · Nov 12, 2014

hows the tensioner?

DEEZUZ · Nov 12, 2014

watch it while it runs, it should have a pretty firm but consistent bounce

mandkole · Nov 12, 2014

Chirping is a gradual wearing of the belt's rib profile, driven by pulley misalignment. Have you changed the tensioner or any of the pulleys recently? If the tensioner is older it likely has some arm misalignment. Also, the belt spans around the tensioner are the shortest and the most susceptible/sensitive to misalignment. Higher mileage vehicles are most common as the belt/pulley rib fit is marginal when the belt is new and quickly gets worse with a little belt wear.

Its the most common belt complaint that we deal with in our automotive replacement division.

supermoto · Nov 13, 2014

Not sure if your's is the same issue, but I experienced a similar sounding issue with a new belt - I learned there was a different size or two - using the smaller size belt resolved my issue. I believe this is what I ordered:

GOODYEAR 4081215

cbf9703 · Nov 13, 2014

CTC DEEZUL said:
hows the tensioner?

X2 I had a bad tensioner that would trash a belt, fixed the problem instead of warranting a bunch of belts.

Jomax · Nov 13, 2014

An excursion belt at Ford is slightly smaller. That fixed my issue. That and check your water pump pulley. If it's really shiny, scuff it up some.

Sent from my SM-N900V using Tapatalk

mandkole · Nov 13, 2014

Jomax said:
An excursion belt at Ford is slightly smaller. That fixed my issue. That and check your water pump pulley. If it's really shiny, scuff it up some.

Sent from my SM-N900V using Tapatalk

Using shorter belts just preloads the tensioner spring more. Its bandaiding a bad or wearing tensioner...

Arisley · Nov 13, 2014

Beat me to it. If a tensioner fails, it will shred a belt. Stopping you on the side of the road and causing peripheral damage. It is much cheaper to replace the tensioner or other out of alignment pulley than it is to band aid fix it.

PABowhunter · Nov 13, 2014

Thanks for the input guys. I'm gonna check that belt tensioner when I get home. Is there anything specific I should look for besides alignment and proper tension?

mandkole · Nov 13, 2014

at Gates, we call the tensioner inspection 'spin-cycle'--

1) spin the idler and listening for unusual noise, dry bearings,etc.

2) then, cycle the tensioner arm back and forth, feeling for issues with movement or alignment issues. The tensioner may look OK at 'free arm' position (no load) but will begin on misalign as you load it up. As tensioners wear, the pivot bushings wear and cause misalignment of the arm to base.

The factory tensioners on the 7.3s are not high content parts and dont have a lot of life. They usually develop issues by 3 yrs/ 75-80K.

A good running tensioner and well designed layout should have almost no arm movement as the belt is running on it.

OBS-Addiction97 · Nov 14, 2014

mandkole said:
at Gates, we call the tensioner inspection 'spin-cycle'--

1) spin the idler and listening for unusual noise, dry bearings,etc.

2) then, cycle the tensioner arm back and forth, feeling for issues with movement or alignment issues. The tensioner may look OK at 'free arm' position (no load) but will begin on misalign as you load it up. As tensioners wear, the pivot bushings wear and cause misalignment of the arm to base.

The factory tensioners on the 7.3s are not high content parts and dont have a lot of life. They usually develop issues by 3 yrs/ 75-80K.

A good running tensioner and well designed layout should have almost no arm movement as the belt is running on it.

What brand do you recommend? I replaced my tensioner on my 97 with one from napa which appeared more heavy duty and was larger.