Belt chirp

[kook911]

This is driving me crazy as it just started recently. The problem. When I first start the Jeep it will chirp till warmed up. Once warmed up and at idle the chirp goes away. If you push on the gas the chirp will increase with acceleration. I have done the water test and once water is sprayed the chirp goes away. 

 

Things that I have done. I removed the belt and cleaned it with soap and water. I also checked all the pulleys by hand and all turned freely and spin. I have tightened the belt and no changed of noise. I have checked the alignment of the power steering pulley and it lines up with the water pump pulley. 

 

Everything that I read is saying that I have a pulley misaligned. The only pulley that has ever been off the Jeep is the power steering pulley. I don’t have a laser to check it but I did use my straight edge. Harmonic balancer looks good also. So do you have any tips or other suggestions that I can look at to try to fix this problem.   

[HOrnbrod]

P/u a mechanics stethoscope and listen at each pulley while the engine is running. That'll tell you quickly where the chirp is originating. I like the Lisle 52500, not expensive and amplifies the foreign sounds well.

 

[AZJeff]

Belt tension on the 4.0 has to be INCREDIBLY high to avoid slippage/squealing/chirping.  Are you tensioning the belt to the recommended level and using a tensioning gauge?

[Jeep Driver]

You say you wash the belt with soap and water which tells me it was saturated with oil and a saturated belt cannot be cleaned and it will chirp

[JustEmptyEveryPocket]

I have had the same issue on two different 4.0L engines. In both cases everything seemed to check out and replacement belts chirped also. I checked and had the same findings as you report. The problem ended up being the harmonic balancer for both of them. Even though it looked fine from a visual examination, it must have been the culprit because as soon as it was replaced the noise went away. If you do this make sure to get both the removal AND install tool. I managed to only rent the removal tool, which meant an unnecessary trip into town and back.

[grumpiebill]

This is driving me crazy as it just started recently. The problem. When I first start the Jeep it will chirp till warmed up. Once warmed up and at idle the chirp goes away. If you push on the gas the chirp will increase with acceleration. I have done the water test and once water is sprayed the chirp goes away. 
 
Things that I have done. I removed the belt and cleaned it with soap and water. I also checked all the pulleys by hand and all turned freely and spin. I have tightened the belt and no changed of noise. I have checked the alignment of the power steering pulley and it lines up with the water pump pulley. 
 
Everything that I read is saying that I have a pulley misaligned. The only pulley that has ever been off the Jeep is the power steering pulley. I don’t have a laser to check it but I did use my straight edge. Harmonic balancer looks good also. So do you have any tips or other suggestions that I can look at to try to fix this problem.   

Look at the harmonic balancer closely. Is it tubing the timing cover?

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[grumpiebill]

Rubing...rubing the timing cover...don't wait too long

Look at the harmonic balancer closely. Is it tubing the timing cover?

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Sent from my LG-M210 using Tapatalk

[Motorhead X]

I second the proper tightening of the belt using a brand new quality belt.

[87MJTIM]

My vote, and experience - harmonic balancer.

[WahooSteeler]

I have this same issue and it drives me nuts. New belt and idler pulley in the past year, no help even though the bearing on the idler was worn out. It seems that when the engine is reallly warm, like after highway driving, it goes away. When I had a new A/C compressor installed recently, I told the shop to make sure the belt was about another turn on the tensioner from what they would consider normal deflection. The owner who I normally deal with was off that day and the other guy looked at me like I was crazy and said it would shorten the life of the bearings on all the pulleys yada yada yada. I said I know, but just do it. It was chirping before and now it's tight as crap and still chirps. Most things I've read on this seem to lead back to the harmonic balancer so I guess that's next for me. 

[PIKE]

http://www.daycoproducts.com/dayco%C2%AE-belt-tension-gauges

[grumpiebill]

Just did the Harmonic Balancer on my WJ 4.0 last week. I thought at first it was an idler. Either the tensioner or idler pulleys. I took the belt off to check pulleys and then fired it up to see if noise was still there. Sure enough noise was still there. Closer look...balancer pulley had come loose from its rubber bonding, shifted inboard and was rubbing the timing cover...as I said before don't wait too long. Its a big leak if you do. I found a very reasonable price on eBay...

This is driving me crazy as it just started recently. The problem. When I first start the Jeep it will chirp till warmed up. Once warmed up and at idle the chirp goes away. If you push on the gas the chirp will increase with acceleration. I have done the water test and once water is sprayed the chirp goes away. 
 
Things that I have done. I removed the belt and cleaned it with soap and water. I also checked all the pulleys by hand and all turned freely and spin. I have tightened the belt and no changed of noise. I have checked the alignment of the power steering pulley and it lines up with the water pump pulley. 
 
Everything that I read is saying that I have a pulley misaligned. The only pulley that has ever been off the Jeep is the power steering pulley. I don’t have a laser to check it but I did use my straight edge. Harmonic balancer looks good also. So do you have any tips or other suggestions that I can look at to try to fix this problem.   

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[JMO413]

I had a similar squeak and it was the idler pulley. It looked good spun good by hand. I finally took it all apart again and the bearing in the pulley was junk. Wouldn't spin by hand.

[AZJeff]

Guys, this topic has surfaced 8 bazillion times on XJ forums.

 

Yes, the HB can go bad, and a careful visual examination with an inspection mirror and straightedge can rule out any issues there.  Obviously an HB that has deteriorated will cause belt noises.

 

That said.....Nobody who is not familiar with the XJ/MJ 4.0 belt routing has any comprehension on how tight the belt has to be to avoid noises.  "Finger testing" the belt for tension is totally inadequate for judging proper tension.  A belt tension gauge is mandatory for good results.

 

End of factual rant.

[kook911]

Thanks for all the advice.  I am picking up a new belt.  I also got a new idler pulley but it still had the squeal.  I took the belt off and started the jeep and the squeal is not there.  I am pretty confident that the water pump bearings are going out.  So I am going to swap that out this weekend and will update once I get that complete.  As for the the balancer I looked at it and there is no rubbing that I can see or rubber coming out. 

On 11/15/2018 at 6:48 PM, JMO413 said:

I had a similar squeak and it was the idler pulley. It looked good spun good by hand. I finally took it all apart again and the bearing in the pulley was junk. Wouldn't spin by hand.

How do you take them apart?  

[JMO413]

I just meant I took the insert out so I could spin the pulley. That's when I figured out it was just spinning on the insert. 

[gogmorgo]

I had my harmonic balancer go bad as described above. Not even particularly noticeable separation of the rubber bit, but it was enough to create a small wobble that slapped the belt against the timing cover once per revolution, and the belt was winning. No damage to it.

The engine's sitting in my shed now with no belt on it but you can still see the groove the old belt cut into a raised bit on the timing cover. 

 

There wasn't anything wrong with the belt either. I reused it with the new HB. 

As far as replacing the HB goes, as was said above the puller kit is definitely helpful. If you can't get the install kit, just use a bolt that matches the balancer bolt but 3/4 of an inch longer, and some washers to stack under it for when it bottoms in the crank. Don't try pulling on a harmonic balancer with the factory bolt. You won't have much thread engagement and you'll risk stripping out the end of the crankshaft, which would be a major pain in the @$$ to address.  

[AZJeff]

Just a reinforcing comment here -- OP cites two symptoms that are HIGHLY indicative of belt slip:

 

1.   noise is reduced or eliminated (temporarily) by wetting the belt

2.   noise increases as engine (and accessory drive belt) is accelerated

 

These point to a belt tension,  belt condition, or pulley cleanliness issues and not bearing related problems.

[kook911]

18 minutes ago, AZJeff said:

Just a reinforcing comment here -- OP cites two symptoms that are HIGHLY indicative of belt slip:

 

1.   noise is reduced or eliminated (temporarily) by wetting the belt

2.   noise increases as engine (and accessory drive belt) is accelerated

 

These point to a belt tension,  belt condition, or pulley cleanliness issues and not bearing related problems.

True. I took off the old water pump and put a new one on there. When I just spray water on just the water pump it quite down and came roaring back. So I was thinking the water pump bearing went out on me. Started the Jeep tonight and sound has gone. Will tell once I drive it to work. 

[kook911]

Just updated this.  It was in fact the water pump bearing going out.  The water pump was not leaking but it as squealing.