Tracking down a belt squeal / squeak

Grn02tj

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Feb 16, 2019
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Columbus
2nd post. First wrangler. Owned it close to a year.
When winter hit, my belt started crying at me. It started as a squeak. At this point the idler pulley, tensioner and belt were replaced withing 5 months and it hadn't made a noise.
Winter hit, and it came back. Noise Changed when I sprayed water on it. Changed when I removed parts and put them directly back on without replacing them.
I thought water pump and fan clutch. NOPE. Was exactly the same. So next I pulled my belt, idle and tensioner and replaced them under warranty.
Which is where I'm at now.
Alternator works great. Charges great. Steering box leaks, but not on my belt.
I'm not expecting a definite answer, just opinions.
I really might take it to a shop just to have them take a stab at it.
 
Does it squeal when idling or, at reasonably low RPMS when not in gear? If so, take a rubber or vinyl hose of about 4-5 feet and use it as a poor-man's stethoscope to probe around to try and localize the noise. This may require a helper to do engine revving duties but can really help track down that pesky squeaker...sometimes, despite our stereo hearing, just listening is not enough to determine where a noise is coming from...especially squeaks and rattles.
 
I've kinda done this. It sounds like it in the area of my idler or tenisioner. But I've replaced them literally 20 miles before. Maybe a cheap belt? The belt was also replaced 12 hrs ago. Autozone belt.
Maybe an alternator bearing being bad but it still charges at full strength. Its been tested. But the bearing/pulley is a little rusty. Its literally driving me crazy.
 
A possibility that has, interestingly, come up twice recently, is the possibility of a too-long belt. Take a look at the belt where it pases by itself when it runs over the idler. It should look something like this with about 1 - 1.3 inches distance at the closest point. If it's much less, your belt is too long and the tensioner can't keep it tight enough to grip.
I had this problem and resolved it with a Dayco Poly Rib 5060883 belt.

P.S. The fact that the sound changes when spraying water would also lend credence to this theory as most bearings (unless they're REALLY bad) will not react immediately to water spray).

P.P.S. Also look for signs of oil contaminations on the belts or pulleys (I think you've already done this, but just checking).

EDIT: just realized I didn't attach the picture...here 'tis.
77838
 
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Out of curiosity did you replace a belt driven accessory before belt noise started? Squeal started at mine after I had to remove idler pulley to change water pump.

Running down same problem as we speak, definitely narrowed it down to belt slippage at the idler pulley. Noise goes away when water was added. It also goes away when you just flat out take the idler pulley out of the loop. Tried cleaning belt with various degreasers and cleaners no real improvement. Tried playing with tension, no improvement. Belt seems to be in alignment when stopped but alignment looks out as engine is ran. Gonna shim idler pulley and see if that helps.
 
I'm pretty certain it's my alternator now. I've pulled the autozone tensioner and idler and belt and replaced them all with napa parts. It kind of changed after that, but is back to normal squeaking. Pulled off the belt and the alternator bearing seems grindy. Eveything except power steering, alternator and harmonic balancer has been changed. 100% coming from idler area but I cant pinpoint it.
 
It's an 02. And also an automatic tensioner. I'm pretty sure it's an alternator at this point. It registers 14v on the dash. Never given me a problem. It's a Denso so it probably good charging wise, just old.
 
No way I know of to test without just replacing it. Be sure to get one with a decent warranty as the rebuilt units are somewhat notorious for failing.
 
An alternator with a bad bearing may not have any issues charging. As long as the stator, rotor, diodes, and controllers are fine it won’t present any symptoms electrically.

However the bearing will eventually fail and seize and tear up your belt (leaving you stranded) so it should be replaced.

Now would be a good time to consider a Durango alternator upgrade or a high output alternator if you think you’ll be adding accessories in the future.

The new Durango alternator might even be the same cost as the new TJ OEM specified alternator.
 
2nd post. First wrangler. Owned it close to a year.
When winter hit, my belt started crying at me. It started as a squeak. At this point the idler pulley, tensioner and belt were replaced withing 5 months and it hadn't made a noise.
Winter hit, and it came back. Noise Changed when I sprayed water on it. Changed when I removed parts and put them directly back on without replacing them.
I thought water pump and fan clutch. NOPE. Was exactly the same. So next I pulled my belt, idle and tensioner and replaced them under warranty.
Which is where I'm at now.
Alternator works great. Charges great. Steering box leaks, but not on my belt.
I'm not expecting a definite answer, just opinions.
I really might take it to a shop just to have them take a stab at it.

Did you end up fixing this? I've got the same issue and I've done the same things to attempt to fix it.
 
Just to chime in on this, I just noticed a squeal coming from my alternator 2 nights ago. My assumption is a bearing going bad. I plan on getting a high output unit this weekend or next. Any suggestions would be appreciated as I run a winch and 8 halogen fog lights.
 
Just to chime in on this, I just noticed a squeal coming from my alternator 2 nights ago. My assumption is a bearing going bad. I plan on getting a high output unit this weekend or next. Any suggestions would be appreciated as I run a winch and 8 halogen fog lights.

I actually had an alternator squeal and replaced as well, but Both of these happened on my TJ. Actually, my TJ is boring, it literally never beats the odds, every “this happens on 2005’s” I read, it shows up, ha.

I bought this Db Electric to replace my Alternator and it’s run my battery fine with my 6 Halogen KC’s and Hogh output headlights. I’m not sure it hurts, but I got a lot of advice that the high output alternator isn’t really necessary for my 1 battery setup etc.

1669990646875.jpeg
 
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i would go ahead and replace all the pulleys and bearings where you can. i swear by the gatorback belts, crown now sells them.