PackMule1911

Hello Folks,

Traded for my first Jeep yesterday: '01 Cherokee Limited. Hearing some things now that I didn't hear when I test drove the car. I've search some for help on a what I'm hearing, but since I've got two different concurrent noises, I thought it would be OK to ask.

Noise #1:

- Origin sounds like driver front origin.
- Sounds like the constant honing of a knife, metal on metal, but not grinding, and a not a really sharp sound.
- Noticeable from 20mph and up, and then stops being noticeable when I decelerate.
- No "pulse" that changes as the car goes faster, but the volume seems to increase with speed.
- Front differential fluid was checked and topped off by the dealer's mechanic. He said to drive it for a while and see if it improves or goes away.

I would image something like a bent rock shield lightly pressing on the rotor, or maybe the caliper applying too much constant pressure. Thoughts?

Noise #2:

- Driver side front origin.
- Pulsing "rah" sound. Not really a "whump" like a tire or wheel bearing.
- Pulse dictated by speed.
- I would think it's a wheel bearing just starting to go, or maybe a bad tire.

Am I off-base, on the right track? I went from an Acura MDX cocoon of silence and comfort to this Jeep, which I am very happy about, but I've got a lot of differences to get used to still.

The tires look to be new (Goodyear Assurance). The mechanic put the car on the lift, put it in gear, and used a scope to check the sound of all the bearings. Reported to hear nothing bad from anywhere.

I personally have not done the wheel bearing test yet, rotated the tires, or removed the calipers. Just got the car, not keen on sharing bad news with Mrs. so soon after getting the car, and am hoping for a simple and inexpensive problem to fix.

Thanks for the guidance and patience with the a newbie.

Radi

Probably a good time to see what's left of the front brakes, u-joints and general suspension condition.

PackMule1911

Rotated tires tonight and there's no change. Tried the wheel bearing test and they don't seem worn.

Plenty of rotor and pad. After I drove it tonight I checked to see if the brakes were really hot, thinking the calipers are seized. They're not abnormally hot. It did seem that the homing sound disappeared when I applied the brakes enough to start to stop. Maybe they're not releasing enough?

Radi

I'd take a close look at the ujoints in the front axles and driveshaft then.

What is the "homing sound"? The grind noise?

PackMule1911

Will do.

It's like metal and metal are pressing against each other, but not really hard. Not grinding; softer sounding than that. I imagine it's what the brake pads and rotors would sound like if they weren't quite separating enough when you take your foot off the brake. Or, it could sound like something spinning that wants some lubricant because it's too dry.

Hard to describe sounds sometimes.

4OHI6

Jack front tires off the ground and spin them and see if you can hear anything. Wheel hubs can make various noises as they start to go out. My passenger hub start making an odd noise from 40-50 recently. I hadn't narrowed down to passenger side, so I started with driver side and replaced hub and ujoint. No change in noise. After passenger side it was so smooth like a new vehicle.

Plus all the other suggestions so far.

PackMule1911

When I had the tire off I rotated the wheel and it sounds like I tried to describe, a light honing sound. I'm not confident in concluding what the source is. I assume it's not the hub because of the 12 and 6 test. I'll try to check the u-joint once I learn how to troubleshoot those.

I understand that the pads are in some contact with the rotors. But don't they release also? If the pins aren't lubed that would restrict the movement of the calipers, yes?

Regarding the sound, the tech didn't hear anything bad when he had it in the air and was using his scope.

Crazy 8s

The piston in disc calipers can be a bit sticky and let the pads lightly rub on the disc...resulting in the knife honing sound you hear. I don't think it is a huge issue, but it could also be an indicator of future failure. If you are handy, you could rebuild the calipers for just a few bucks.

Crazy 8s

Nice looking Cherokee, btw! Cheers!

4OHI6

The pads will make light contact. You should be able to spin the tire by hand and it will have a little resistance. My hub showed no movement by the 12/6 test. It just made a droning noise when I hit 40mph. Any idea how many miles are on the hubs? Has it been ran off-road at all?

Also inspect front Drive shaft u-joints. You can remove front drive shaft and drive it to see if any difference.

PackMule1911

No idea on the miles of the joints of if it was driven off road. It seems like a city and highway car to me.

Just take the front drive shaft off and drive it? Make a mark on it though, right, since it matters how it's positioned?

I can easily swap out the calipers if that's needed. I did notice that the rotors are circular ridges. I would think that would make for a poor mating surface with the pads and cause excessive noise.

PackMule1911

Thanks. It's pretty clean, but I'm starting to wish I'd had it looked at more closely before I traded. Hopefully it will work out well after a shaky start.

4OHI6

Yes, mark it before taking off. Inspect the ujoints in the shaft for any movement. Remove and then test drive in 2WD, obviously.

md21722

You could take your front driveshaft out and see if it goes away. Theres a centering ball in the double cardan joint that gets dry and causes noises that some call "angry sparrows". There is also a chain in the transfer case that can wear and when it wears it gets longer and rubs against the aluminum case. You can also change from 2WD to 4WD and see if the noise changes. Do not run "4Hi" on dry pavement with the driveshaft installed.

PackMule1911

Driver side wheel bearing done (my first go at that job), and the sound remains.

A mechanic friend drove it around and in 4WD some, switched to N, and the sound remained which I was told rules out the pinion. It seemed to diminish when swerving to reduce the load on each side, which we thought would confirm the wheel bearing.

I'll get to the passenger side wheel bearing and try the other tests as soon as I can.