Can't figure out this noise

Ok, this has been getting worse for about a week now. At the rate it's going it might just go out/grenade/catch fire before you guys can figure it out but ether way I'll at least know what it is then.

First off this is a 96 Cherokee. 4.0, ax15, 4x4, A/C (that works), with 220k on it.

It is making a squealing noise very similar to a belt slipping. It only does it during acceleration, it's only loud in 1st and 2nd. 3rd is quieter, 4th and 5th you almost can't hear it at all. It changes with engine load (hit the gas it gets louder, let off/hit the clutch it stops). Reving it in neutral it doesn't do it at all.

Any thoughts? I have a vid of it I will try to post too


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If you are sure it isn't your belt slipping then I would suspect the fan hub bearing in the a.c. compressor bracket.

Xjnk2500 said:

It is making a squealing noise very similar to a belt slipping. It only does it during acceleration, it's only loud in 1st and 2nd. 3rd is quieter, 4th and 5th you almost can't hear it at all. It changes with engine load (hit the gas it gets louder, let off/hit the clutch it stops). Reving it in neutral it doesn't do it at all.

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With the engine dead cold, take off the serpentine belt and start the engine. Does the squealing stop? If so, check the movement of the pulleys, they should turn smoothly, but obviously with effort in some cases. If they squeal or feel out of round-replace them.

J

If it squeals with the AC on, I'll bet the belt is slipping.
My 96 did the same and tightening the belt fixed it.

Ok so to make this even more odd. When I got off work tonight it didn't make a single squeak. But all the way there it did it. The A/C on or off makes no change by the way. I will try to remove the belt tomorrow and see if that changes anything.


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Xjnk2500 said:

Ok so to make this even more odd. When I got off work tonight it didn't make a single squeak. But all the way there it did it. The A/C on or off makes no change by the way. I will try to remove the belt tomorrow and see if that changes anything.


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The load on the alternator or AC will effect it if it's belt related. If it's bearing related, temp and humidity will change the properties of what little grease is left.

J

Bad harmonic balancer.

Or bad idler pulley, had a bad one squeak intermittently before it totally failed.


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Ok well I feel really dumb now. I finally got a chance to go work on it. Pulled it up and down a hill a few times and it was going with the rpm of the drive line not the engine. So I slid underneath and low and behold my back u-joint was shot! Never noticed it much because my a tranny has 350k on it so it has some slop in it without the bad I-joint.


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