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Squeeking/Squeeling/Rattling from the Accessory Drives

Rick Anderson

NAXJA Forum User
Location
Lusby, MD
This is a '95 Cherokee 2WD, 2.5 L4, AX-5, w/AC,PS. 200k miles + the vehicle has been garaged the last year fixing a rusted out floorpan, I'm just getting the motor up and running again.

I'm getting an awful loud squeal/squeak when I start the motor,when its cold, the noise is associated with engine speed. It gradually dissipates as the motor warms up.

It doesn't sound like belt squeal, I'm thinking it might be idler or bearings on the AC pulley or Alternator. As well, once the squealing has dissipated as it warms up, there is still a rattle coming from the same area, this sound seems to be the fan or its thermal clutch.

Are there any common causes for these noises? Any test or checks I can do to narrow down the problem items and eliminate the noises? This is a 2.5L L4, I don't know if it has the same damper/crank pulley as the 4.0L L6, does the 2.5L crank pulley/damper start to fail and make noise as well? How do you check the condition of that?
 
The wife,s 98 had the same issues,it was a 4.0,but noise was a bad AC clutch bearing.An easy replacement,if it is replacable on your unit,but costly.
Wayne
 
I'd look first at the idler pulley. This is a pretty common problem, and the pulley is not expensive to replace. You may not feel it wobble, but if you take the belt off (or even just take the pulley off - you can unbolt it with the belt still installed) you can give it a spin, and if it's rough, replace it.

It could also be the bearing in the fan bracket, but this is less common, so I'd suspect the idler first.

Often a bad bearing will stop squealing when it heats up.
 
I was afraid of that, but it does sound like its coming from that area. Unfortunately, all the rotating parts on that belt are so close together, you can't really tell which one is making the sound.

The rattle really sound like the fan, its very similar to the sound of hitting the fan blades with something metallic (NO there is nothing actually contacting the fan), but constantly happening, could this be the thermal clutch creating the racket? I'm thinking any noise/vibe/shock from the clutch is being carried out from the fan blades. How does a fan create rattle noises if nothing is hitting it?
 
Matthew Currie said:
It could also be the bearing in the fan bracket, but this is less common, so I'd suspect the idler first.

Often a bad bearing will stop squealing when it heats up.
Thanks, thats what I suspected, a bad bearing on at least one of the rotating parts, and I can afford new idlers but NOT a whole new AC clutch.

Anyone know where to find just the bearing for the AC pulley/clutch? If it turns out to be the AC pulley/clutch bearing, everything else is good for that unit. I've only seen it sold as an entire unit for $240. I should be able to take it apart (done it on other vehicles), I would think it shouldn't be hard to press the bearing out/in on the pulley.

Matthew Currie said:
It could also be the bearing in the fan bracket, but this is less common, so I'd suspect the idler first.
Bearing in the Fan Bracket?? What and where is that?? Internal to the Thermal Clutch??

The rattle really sounds like its coming from the fan (thats my perception, NOT fact). Nothing is touching the fan, so I'm guessing it has to be something internal to Fan Clutch or even the water pump bearing.

BTW, the fan shroud is off the radiator at the moment, I don't see how that would create noise either, but it is different than the proper setup.
 
On my 85 2.5L I began to get a rattling noise around 270,000 miles that turned out to be the timing chain and tensioner. It did not go away as the engine warmed up. The alternator bearing went about the same time and the noise from that did decrease as it warmed up.

There was a thread some months ago (time flies -- maybe a year) about changing the AC clutch bearing including a part no. (for the Sanden 508?) I plugged the number in on a Google search. I don't recall exactly how many hits I got but know there were several sites with the cost around $20. I have all this earmarked but unfortunately on our old computer currently not set up.

The 85 2.5 doesn't have an idler pulley -- don't know about later years.
 
I have a '96 with same engine, trans etc.

On mine I bypassed the air conditioner pulley to keep the Jeep going by using a shorter non-air serp. belt. It's a direct replacement without the extra air conditioner "loop".

As summer is coming soon I will need to tackle the air and deligate to non-air belt to back-up which seems like like a good thing to because you can drive home without air but not without a belt.
 
Rick Anderson said:
Thanks, thats what I suspected, a bad bearing on at least one of the rotating parts, and I can afford new idlers but NOT a whole new AC clutch.

Anyone know where to find just the bearing for the AC pulley/clutch? If it turns out to be the AC pulley/clutch bearing, everything else is good for that unit. I've only seen it sold as an entire unit for $240. I should be able to take it apart (done it on other vehicles), I would think it shouldn't be hard to press the bearing out/in on the pulley.


Bearing in the Fan Bracket?? What and where is that?? Internal to the Thermal Clutch??

The rattle really sounds like its coming from the fan (thats my perception, NOT fact). Nothing is touching the fan, so I'm guessing it has to be something internal to Fan Clutch or even the water pump bearing.

BTW, the fan shroud is off the radiator at the moment, I don't see how that would create noise either, but it is different than the proper setup.

The shaft that the fan turns on is built into the bracket beneath the AC pump. That can go bad, but it's not nearly as common as the idler.

It's also possible that a badly worn fan clutch can rattle. There's a bearing inside the fan clutch itself, and that can wear out. So can the water pump, of course, though in my experience that usually rattles more. You're not going to be certain until you take the belt off and start spinning and wiggling.

If it's the bearing in the AC clutch, you can test that in a jiffy if your AC is working. Turn it on. If the noise stops, you have your culprit. If not, you don't.
 
Matthew Currie said:
The shaft that the fan turns on is built into the bracket beneath the AC pump. That can go bad, but it's not nearly as common as the idler.
Ah, I see where we are getting confused. This is a 2.5L L4, it sounds like your talking about the far more common 4.0L L6. The 2.5L has a more conventional radiator, that is squarish/rectangular with the long side orientated up/down in the center of the header. It just uses one fan, and that fan/thermal clutch is mounted on the waterpump of the motor.

I think the 4.0L has the super-wide radiator, that uses 2 fans, the engine driven one being offset toward one side of the motor. Thus the bracket and bearing your speaking of, thanks, but it doesn't apply in my case.
 
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