chrisl757

Hi all,
I have a 2001 XJ, 4wd, 4.0, 185K miles.

There is a whine that I have noticed for a while that is coming from the engine. I have some experience with XJ's (this is my 3rd XJ). The whine varies with the RPMs of the engine, so it gets a higher pitch at higher RPMs. There is a whine even when the car is at a stop and running, so I know it is not a bad wheel bearing.

Now, aside from that whine, I had a high squeal from the AC (not the whining noise I mentioned above) when I turned the AC on and the squeal would go away after about 5 seconds. I read on here that if I tightened up the belt, that it would take away the squeal because the fan might be slipping when the AC kicks on. So, yesterday I tightened up the fan belt. The squeal is now gone, but the whine has gotten worse and it is making me worry. This is my DD and my only transportation for me and my little boy (single dad).

I can turn the wheel left and right and it doesn't affect the whine, so it's not the power steering, and the fluid level is good on the power steering.

I just changed the oil this weekend and it looks good.


That seems to leave a few things:

1. water pump?
2. AC compressor?
3. alternator?
4. Transmission????

It is hard to tell if it is coming from any of the above, although the AC compressor is noisy.
Is there any way to figure out where this is coming from? Should I take the belt off and spin the pulleys to see if they are tight?

I am guessing that this is some sort of a bearing issue, but I really could use some help.

Thanks to all for reading all this.

Jjs2000xj

Taking off the belt is easy enough so doing that first like you suggested, would be a good start....IMO. If all of your accessories are original or well used it seems as though it could be any of them without directly hearing the sound for ourselves. Keep in mind, the speed and tension of the belt on and running normally can exasperate the sound much more than jar by hand.

cruiser54

Here's the answer.

chrisl757

Thank you. When I do take the belt off, what am I looking for? Should I just spin the pulleys? How much resistance should I feel and should the AC pulley feel the same as the other pulleys?

Thanks

cruiser54

Spin them and listen/feel. Hard to explain. Easy to figure out once you're in there. Report back what you find.

CCKen

Run the engine with the belt off for a minute and see if the whine goes away. If so you know you're in the right ballpark. Just a matter of pinpointing the bad guy.

I had a whine (of sorts) not long ago and I found the alternator bearings were shot using a mechanics stethoscope. The alternator and water pump can be checked with the stethoscope but the idler pulley will need to be removed and checked by had.

chrisl757

Just so I'm sure, you're saying to pull the belt, and just start the engine for a while to see if the same sound exists? I guess that would rule out the transmission being a problem.

Can I manually push the throttle control when I'm under the hood to see if that makes the whine worse? I used to do that when I had an old Bronco with a carburetor, but I've never tried it on my jeeps.

ThatAintStock00

You're right on track. My '00 does it. Sounds like a supercharger. Seriously. I need to test mine but for right now i'll give people reason to wonder....

and you can push the throttle just like the old carbs we were so fond of.

CCKen

Yes.

Lw2044

Its one of your pulley bearings. Spin them by hand and see which one is the loudest and doesn't turn smoothly.

chrisl757

I didn't have time to pull the belt last night, but I did lift the hood and listen very closely to the pulley sounds when I revved the throttle. The sound appears to be coming from the front passenger side. I put a long crescent wrench on the body of the compressor and tried to feel for vibrations (like a tuning fork?).

Anyways, I'm not sure I did it right, but I could definitely feel the vibrations increase from the compressor when the throttle went up.

Just for curiosity, I put the wrench on top of the valve cover and I could feel the vibes being transmitted all the way over there too. If I can find the source of this, things are probably going to get a lot quieter under the hood.

I'm going to pull the belt tonight and see how the pulleys feel. My hunch is that it's the compressor, or maybe the alternator.

Both the compressor and alternator are original equipment.

OleBlue

If you do run the engine without the belt, dont do it for very long. No water pump pumping water is a bad thing!

MACherokee

Have the same whine... sort of a high pitch whistle.... mechanic said it was alternator bearings....

chrisl757

Hi All,
I took the fan belt off and here's what I found:

The Fan spun just fine.
Power steering seemed normal.
Idler puller was smooth spinning and no noise.
The water pump had just a bit of resistance and it made a slight noise, but it turned relatively easy.

The alternator pulley was hard to reach with the fan blades in the way, but it still turned without any noise, and it was smooth.

My AC pulley would spin just fine, but it had a hiss sound that sounded like metal on metal.

I did turn on the engine for about 20 seconds to listen, and the noise was totally gone, which is good since that rules out any transmission issues.

Then I put the belt back on, tightened it up and started the engine. Since I didn't put the fan shroud back on, I was finally able to see how the AC clutch engages (never saw that before).

Here's the deal: The sound gets much quieter when it seems like the clutch engages (or when the center part of the pulley stops rotating--wouldn't that be the clutch engaging?). I guess I mean that I hear the AC kick on, but the whine that I've been chasing seems to get much quieter. If that part is the culprit, it makes sense that the noise goes away when it stops rotating.

I'm open to any thoughts, but this seems to me like it's the AC bearings in the compressor.

One thing I should say is that my AC blows cold air just fine, and so I'm wondering if I can play around with the belt tension a little to see if there is a sweet spot to keep the noise from a roar.

I'm assuming these bearings are enclosed so that one can't just spray some lubricant in there.

Is there any way to replace just the bearings since the AC works fine?

In other news, I finally seem to have found out that my heater core is leaking, and I will need to do that. So, if I have to do an AC discharge, it seems to make sense to do the compressor and heater core at the same time since I'll have to pull the evap lines too. That will be a long long weekend of work. I'm hoping to get by for a few more weeks so I can start buying all the parts I'll need.

chrisl757

bumping to see if there is any way to fix the bearings without having to do a full blown replacement of the compressor.