Chirpy Belt Noise

EJD

EJD

TJ Overlander
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Hey so lately after washing my Jeep in the spray bay and sometimes early in the morning, when I hit the gas pedal i'm getting this chirpy belt noise. The noise does go away after a little bit or after it dries out or something. Since my belt is quite new am I to believe the idler pulley needs to be replaced or is it something else?

Thoughts, ideas?
 
EJD said:
Hey so lately after washing my Jeep in the spray bay and sometimes early in the morning, when I hit the gas pedal i'm getting this chirpy belt noise. The noise does go away after a little bit or after it dries out or something. Since my belt is quite new am I to believe the idler pulley needs to be replaced or is it something else?

Thoughts, ideas?
Click to expand...

I’m not sure if they offered an auto tensioner in later models but I’d say it has just gotten some slack and needs tightened usually happens 1-3k after new belt install
 
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hamrickac said:
I’m not sure if they offered an auto tensioner in later models but I’d say it has just gotten some slack and needs tightened usually happens 1-3k after new belt install
Click to expand...

That’s not all that unusual for a manual tension system, especially if you were on the conservative side at initial installation. Tighten it back up and it should be fine.
 
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hamrickac said:
I’m not sure if they offered an auto tensioner in later models but I’d say it has just gotten some slack and needs tightened usually happens 1-3k after new belt install
Click to expand...
Could be, I have a 2000 and there is a touch over 1k on the new belt. Did the '00 have the auto-tentioner or a way to tighten it manually?

Daryl said:
That’s not all that unusual for a manual tension system, especially if you were on the conservative side at initial installation. Tighten it back up and it should be fine.
Click to expand...
That sounds worth a try but how do I tighten this? Lol.
 
EJD said:
Could be, I have a 2000 and there is a touch over 1k on the new belt. Did the '00 have the auto-tentioner or a way to tighten it manually?


That sounds worth a try but how do I tighten this? Lol.
Click to expand...

Look under your hood and see if you have an automatic tensioner. It’ll look like this:

1203E39B-55AF-4BE9-9395-E6A3195BD2BF.png
 
I just looked at your profile. You have a 2000 4.0, so you have an automatic tensioning system. It’s probably getting weak.
 
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If you have an auto tensioner it’ll be this. If you don’t you’ll have an idler pulley in the same spot that either raises or lowers with a bolt next to it to put tension on the belt

B1E1917B-53B5-428B-A968-CC61F7C259BD.jpeg
 
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Great info.. I’ve been dealing with that same thing as well.. I’ve just been turning up the radio to drown it out!!
 
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I can say I’ve never changed one on the 4.0 but it should be as easy as take it off and put it on. You should have enough room without removing anything.
 
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Well i'll order it up on Amazon and it'll be here in 2 days!
Thanks guys, I really appreciate that super quick and very detailed response from both of you. (y)
 
All it takes is a breaker bar to get leverage on the automatic tensioner and release the tension to slide the belt off. Then a single bolt through the center of the tensioner assembly holds it on.
 
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Daryl said:
All it takes is a breaker bar to get leverage on the automatic tensioner and release the tension to slide the belt off. Then a single bolt through the center of the tensioner assembly.
Click to expand...
Thats awesome, yeah my current one is the original so 165k on that could probably use a replacement. Anything against going with a Gates or should I just go Mopar?
 
EJD said:
Thats awesome, yeah my current one is the original so 165k on that could probably use a replacement. Anything against going with a Gates or should I just go Mopar?
Click to expand...

Nothing wrong with Gates. I always buy OEM unless it’s NLA.
 
Question in regards to swapping out the tensioner pulley...

When you unbolt the T40 thats holding the tensioner pulley on, there is a small o-ring on the backside of it. What is the importance of that o-ring?

I only ask because the hole that the bolt goes through on the new Gates tensioner pulley was wider and the o-ring has no snug effect on the new one. I was just curious as to what its purpose was. I did happen to have a bag of fuel injector o-rings left over that was a perfect fit to go over the bolt and fit the new Gates tensioner pulley snug on the backside in the same fashion as the OE one. Just curious.

And by the way the noise is gone! :)
 
Ok, so the noise is back...

I've replaced the tensioner pulley first, the noise went away. Then a few days later I notice a periodic chirp every now and then, and I realize that maybe I should have replaced the idler pulley at the same time. I replace it with a cheap Dorman pulley, fire it up and no noise. I figure its all good, till a few more days go by and every time I start the Jeep up in the morning the chirpy noise is back with a vengeance. It does eventually go away but i'm wondering what the hell the problem is? It seems to be very loud and noticable for at least 15-20 minutes of driving then quiets down and doesn't happen again till the next day...

Are these symptoms of a bad pulley? or is there a way that I could have tightened it down to much and its not spinning freely enough or something? Any ideas? Should I try getting a Mopar pulley and see if that clears it up?
 
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