Accessory grinding noise on occasion

[HoosierJeeper]

Walked in front of the KJ yesterday while it was idling and heard a very faint grinding noise from something belt driven. Got home and it had quit, it was silent. Today I pulled the fans out and took the belt off to check the pulleys. Everything feels solid and turns quietly, except both pulleys on the tensioner seem to have a little bit of wobble. I also noticed the AC clutch had a bit of wobble if I pressed it on the face, and it was hard to turn, but uniformly hard to turn.

What's normal and what isn't? Both the tensioner and AC clutch have 164k on them.

Thanks!

 

[uss2defiant]

i'd use a mechanic stethoscope to see if those grinding noises came from those pulleys.

 

[HoosierJeeper]

I poked around yesterday with it running with one and didn't hear anything interesting from the AC comp pulley. Didn't know how to get it on the clutch with it spinning lol.

Don't trust myself to get the stethoscope down to the tensioner with it running....I like being able to play guitar lol.

 

[uss2defiant]

I poked around yesterday with it running with one and didn't hear anything interesting from the AC comp pulley. Didn't know how to get it on the clutch with it spinning lol.

Don't trust myself to get the stethoscope down to the tensioner with it running....I like being able to play guitar lol.

pull the shroud out which will give you ample room.
There should be a nut in the middle of the clutch which should allow you to place the stethoscope. The one I bought from HF has been useful.

 

[HoosierJeeper]

The nut doesn't spin? I don't have my shroud cut to fit over the fan, so I'll have to fire it up without the fans I guess.

 

[uss2defiant]

oh it spins, you should be able to see a dimple in the threaded shaft the nut is thread on.

I think might be able to get to it with the shroud still on. I'm not sure. you'll have to check.

For the auto belt tensioner, you can get to it from the side from the air box down at an angle. as long as you can touch any part of the tensioner, you should be able to hear anything bad.

 

[Royy]

I had all kinds of weird noises coming from the tensioner at around 140k.
Initially I just replaced the pulleys on the tensioner. That quieted it down somewhat. Replacing the entire tensioner assembly made all the noises disappear.

 

[HoosierJeeper]

That's sort of what I'm thinking.

The AC clutch wiggle seems normal...as with the Jeep off it's disengaged from the AC pulley and it's spring operated, so there should be some give.

Also one thing I noticed in the winter is when it's around 0 deg, there's a metal on metal "whistle" sound when flooring it...it's done that for the past winters and goes away if it's like 10F or warmer.

 

[GunnerSchenck]

That's sort of what I'm thinking.

The AC clutch wiggle seems normal...as with the Jeep off it's disengaged from the AC pulley and it's spring operated, so there should be some give.

Also one thing I noticed in the winter is when it's around 0 deg, there's a metal on metal "whistle" sound when flooring it...it's done that for the past winters and goes away if it's like 10F or warmer.

Alot of the heat settings use the ac compressor, so it could be that.. could be just when the clutch engages, that's typically when they will make noise when they're going.

 

[uss2defiant]

I can actually hear the AC clutch engaging from inside.

 

[GunnerSchenck]

I can actually hear the AC clutch engaging from inside.

Same here, kind of a whir or humm

 

[uss2defiant]

a little click when it engages then the whirling/humming

 

[LibertyTC]

Ya wobble on tensioner = get new unit..I used a Gates complete assembly.
Link: http://www.jeepkj.com/forum/f196/jeep-kj-liberty-gates-tensioner-belt-56405/

 

[HoosierJeeper]

Glad you chimed in!

When I spun the idler and tensioner pulleys by hand, they spun smooth without grinding, but I noticed they stopped spinning quickly and abruptly just seconds after I took my hand off, unlike the other pulleys which would spin for like 15 seconds or more and gradually slow down. Is that normal?

Just read that thread you linked too...my wobble is with the belt off. I'll see if it wobbles with the belt on tomorrow!

 

[LibertyTC]

HJ I can not remember how long they should spin for, but the wobble should be a hint bearings not good.
It really is not an expensive part and if yours has not been replaced, just get one.
I think 60k miles is a good time to do the assembly and belt anyways.
Edit there should be no wobble belt off either! Time 4 a new one!

 

[uss2defiant]

https://www.gatestechzone.com/en/problem-diagnosis/accessory-drive-system/tensioner-failure-signs

 

[uss2defiant]

as long as there's no grinding noise you should be good.
I think the difference is that those that spin and stop fast are greased filled bearings vs dry bearings.

Which one is dry or filled? IDK

 

[HoosierJeeper]

Got two vids. One of the AC turning off and on and then one of the grindy noise I hear.

AC vid first. Had a help turn it off and on. Don't really see or hear anything odd.
https://www.youtube.com/watch?v=qC7qEQqFaKg

Grinding vid. It was easier to hear with the hood shut and standing in front of the grill. You can kind of see where I was holding my phone- right above the bumper. It seemed more pronounced with the AC on. But the AC pulley and clutch were quiet when I spun them by hand. Could the tensioner be quieter when there's no AC and then when the AC load gets put on it, it gets noisey?
https://www.youtube.com/watch?v=zSUINRqPMzc

 

[Royy]

The sound in the grinding video sounds a lot like what mine did. New tensioner fixed it.

 

[uss2defiant]

i'd try to isolate the source w/ a stethoscope before throwing parts at it.