Serp Belt Slipping/Chirping

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My 2007 2.3L Escape has an issue where when it is hot outside (90F+), AC is running, car is stopped and transmission is in DRIVE, the belt will start chirping. Put it in neutral OR give it some gas and the chirping stops.

I replaced the belt, idler pulley and tensioner a couple years ago and the slipping had stopped but now it is back. Belt and everything still look new. So, a few things:

1) Is this likely the result of the belt getting soft and stretching a bit?
2) Is there something I could clean or maybe spray on the belt that could help?
3) Could this be harming the compressor?
4) Any suggestions on how to permanently fix this other than throw a new belt on every couple of years?

Thanks.
 
NO belt dressing on a serpentine belt! !

What brand of belt did you install? A new Gates gave me the same issue on our van. A Gatorback (now Continental) solved it.
 
Originally Posted By: zrxkawboy
NO belt dressing on a serpentine belt! !

What brand of belt did you install? A new Gates gave me the same issue on our van. A Gatorback (now Continental) solved it.


The current belt is a gatorback and if I remember right was the first one to not have the issue when it was new. All others (OEM & gates) slipped from day 1.
 
Bewst solution to this is something I have used with great success on many vehicles over the years. Take a few dabs of SILICONE lubricant grease (dielectric grease will be fine) and gently spread it on sections of the ribbed side of the belt. About three pea sized portions spread around will do just fine. When the engine runs and warms it will distribute evenly on the ribs. This will stop the squeak, NOT cause belt slippage and will not affect longevity of the belt. DO NOT USE petroleum grease or "belt dressing".
 
+1 something is causing drag on the belt. A worn bearing possibly on the idler pulley, alternator or air pump. Something is resisting turning enough to cause belt slip.

Next time you remove the belt inspect for contamination from oil also and clean the pulley's off if needed.
 
Compressor may cause the chirping like an almost seized clutch or the bearing in the clutch is starting to go bad?
Also check other parts attached to the belt like Alternator, etc.
 
Originally Posted By: Chris142
Dayco makes a quiet belt too. Look in the pullys for built up rubber,rocks etc.


The Dayco "W" belt is a very good quiet belt, much better IMHO than the Gatorback which tend to whine.

OP Check belt alignment first with the old belt in place then remove the belt, check the pulleys for smooth operation and play.
Any misalignment must be corrected with shims, flat washers, pully back spacing, etc.

Clean the pulley with with grey Scotchbrite pad and a little dawn liquid in warm water, rinse and blow dry then brake clean spray. Replace the tensioner if old or original, loss of spring pressure is the major contributor to noise and wear.
 
Originally Posted By: Colt45ws
Are you SURE its the belt slipping? It seems rather unlikely at idle. I would be looking closer at a bearing in the accessory drive somewhere.


Positive. Keep in mind it only happens when all of the following is true:

1) Must be hot outside (90F+ and sunny) and under the hood.
2) The AC must be running
3) The transmission must be in Drive (no noise when unloaded in neutral)
4) Must be stopped holding the vehicle in position with foot on the brake(at stoplight or stop sign)

If any of those things is missing, the noise ins't there. I would have assumed everything was strapped directly to the engine so I don't get why engine loading has an impact on this. I would think this type of noise should happen all the time.
 
Last edited:
Originally Posted By: JMJNet
Compressor may cause the chirping like an almost seized clutch or the bearing in the clutch is starting to go bad?
Also check other parts attached to the belt like Alternator, etc.


In addition to the idler pulley and tensioner being new, the alternator and compressor have both been replaced in the last year. Just about everything on the serp belt is new.

It only happens when it is HOT under the hood. Could be related to a grease or something thinning out...frustrating.
 
I had a 1998 Yukon years ago that I bought with about 50,000 miles on it. The belt always chirped a little and drove me nuts. I bought a new belt exactly like the one that was on there and it would be quiet for a short time and start the exact same chirping again. Didn't matter if it was Gates, GM or whatever, they all did it.
Finally, I got smart and went to Ernie the counter guy who was very knowledgeable and asked what length belt was SUPPOSED to be on my truck. Low and behold, there were two available. The heavy duty alternator option had a half inch longer belt than the standard one. My truck did not have heavy duty charging but someone had put the belt on and I kept repeating the mistake.
Finally got the right belt and end of problem.
 
Originally Posted By: badtlc
Originally Posted By: Colt45ws
Are you SURE its the belt slipping? It seems rather unlikely at idle. I would be looking closer at a bearing in the accessory drive somewhere.


Positive. Keep in mind it only happens when all of the following is true:

1) Must be hot outside (90F+ and sunny) and under the hood.
2) The AC must be running
3) The transmission must be in Drive (no noise when unloaded in neutral)
4) Must be stopped holding the vehicle in position with foot on the brake(at stoplight or stop sign)

If any of those things is missing, the noise ins't there. I would have assumed everything was strapped directly to the engine so I don't get why engine loading has an impact on this. I would think this type of noise should happen all the time.

Okay, I just ask because I watched a compressor that was spinning lock right up in front of my eyes, and the compressor clutch began to smoke rather than the belt slipping over the compressor pulley, so it seems it takes a lot to get a serpentine to actually slip.
 
After many many hours of replacing belts pulleys tensioners more than once DIELECTRIC GREASE was the solution .....

First thought was a bad tensioner not keeping enough tension ...... did not fix the issue

Second try was a second new belt I had thought the first new one had sat around long enough to be hardened and brittle even when it appeared to be 100% new

Three dabs of dielectric grease and it instantly quit squealing
 
I'm going through this right now, on our CRV. I replaced the tensioner because it was rattling and now the belt chirps. I replaced the tensioner again thinking it's defective and not keeping the belt taut; nope same noise. I'll replace the belt, to see if that helps, nothing else was touched 🤷‍♂️
 
I did a brand new belt no change my final solution was the dielectric the pulleys are too smooth or glazed the dielectric is kinda like a tacky film once it spreads out
 
I have an 05 GMC sierra that drove me nuts. I did everything from straight edge to new belt and pulleys. I finally roughed up the idler pulley with 80 grit. Problem mostly solved except in really wet weather at startup.
 
What kind of parts did you use? OEM? Aftermarket?

Besides the grease, another possibility is something driven by the belt (alternator, PS, compressor, WP, etc) being no good, or the pulley on one (or more) of those being no good.

You can try using a Dayco W-belt. It's supposed to help with being quiet. Continental stopped making those polycog belts a few years ago.


🛑

NO

Do not use belt dressing
 
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