HELP - '99 XJ Buzz/Vibration/?

Hello all - it's been a while since I've poked my head in here, but I
hope all is well with y'all.

Anyway, my '99 XJ (AW4 tranny) has developed a very strange
buzz/vibration that I just can't figure out. When driving along,
starting at ~40mph, this noise starts up. It's kind of like being
inside a drum - more of a resonance than a sound.

As speed increases, the vibes will get stronger. But they don't seem to
vary directly with the speed or engine RPM. Like I said, it's more of a
resonance.

It does not vary with road surface, braking, payload, or maneuvers.
Acceleration/deceleration makes no difference. I can put the tranny in
neutral and coast and it makes no difference. In or out of 4wd makes no
difference.

I've looked and listened all around the engine bay and found nothing
that has the same frequency. The Jeep has to be in motion for it to happen.

If I run with the windows down, I hear nothing obvious. AC on/off makes
no difference.

It's a very "heavy" buzz. Kinda like what you'd expect if the center
guide bearing on a big truck's center driveshaft were going out and the
truck was pulling a heavy load. Or possibly what you'd hear/feel if the
AC compressor pulley bearing were going out.

The only feedback is a slight jingling of my keys in the ignition. If I
put a finger on the ignition cylinder, I can feel a very faint vibe that
matches the frequency of the overall drum sensation. But there's no
feedback in the steering or anywhere else.

No work has been done on it, it's not had any accidents, nothing has
changed.

I'm at wits end trying to figure it out. I'd welcome any suggestions.

Thanks to all!

Good write up, hope you find the problem
K.

"Clap Trap" > wrote in message
...
> Hello all - it's been a while since I've poked my head in here, but I
> hope all is well with y'all.
>
> Anyway, my '99 XJ (AW4 tranny) has developed a very strange
> buzz/vibration that I just can't figure out. When driving along,
> starting at ~40mph, this noise starts up. It's kind of like being
> inside a drum - more of a resonance than a sound.
>
> As speed increases, the vibes will get stronger. But they don't seem to
> vary directly with the speed or engine RPM. Like I said, it's more of a
> resonance.
>
> It does not vary with road surface, braking, payload, or maneuvers.
> Acceleration/deceleration makes no difference. I can put the tranny in
> neutral and coast and it makes no difference. In or out of 4wd makes no
> difference.
>
> I've looked and listened all around the engine bay and found nothing
> that has the same frequency. The Jeep has to be in motion for it to
> happen.
>
> If I run with the windows down, I hear nothing obvious. AC on/off makes
> no difference.
>
> It's a very "heavy" buzz. Kinda like what you'd expect if the center
> guide bearing on a big truck's center driveshaft were going out and the
> truck was pulling a heavy load. Or possibly what you'd hear/feel if the
> AC compressor pulley bearing were going out.
>
> The only feedback is a slight jingling of my keys in the ignition. If I
> put a finger on the ignition cylinder, I can feel a very faint vibe that
> matches the frequency of the overall drum sensation. But there's no
> feedback in the steering or anywhere else.
>
> No work has been done on it, it's not had any accidents, nothing has
> changed.
>
> I'm at wits end trying to figure it out. I'd welcome any suggestions.
>
> Thanks to all!
>
>
>

Check your exhaust pipe for contact on the body or crossmember, I had a
similar issue with a '93 XJ.

--
_ _ _ _ _ _ _
Matt Macchiarolo

"Clap Trap" > wrote in message
...
> Hello all - it's been a while since I've poked my head in here, but I
> hope all is well with y'all.
>
> Anyway, my '99 XJ (AW4 tranny) has developed a very strange
> buzz/vibration that I just can't figure out. When driving along,
> starting at ~40mph, this noise starts up. It's kind of like being
> inside a drum - more of a resonance than a sound.
>
> As speed increases, the vibes will get stronger. But they don't seem to
> vary directly with the speed or engine RPM. Like I said, it's more of a
> resonance.
>
> It does not vary with road surface, braking, payload, or maneuvers.
> Acceleration/deceleration makes no difference. I can put the tranny in
> neutral and coast and it makes no difference. In or out of 4wd makes no
> difference.
>
> I've looked and listened all around the engine bay and found nothing
> that has the same frequency. The Jeep has to be in motion for it to
> happen.
>
> If I run with the windows down, I hear nothing obvious. AC on/off makes
> no difference.
>
> It's a very "heavy" buzz. Kinda like what you'd expect if the center
> guide bearing on a big truck's center driveshaft were going out and the
> truck was pulling a heavy load. Or possibly what you'd hear/feel if the
> AC compressor pulley bearing were going out.
>
> The only feedback is a slight jingling of my keys in the ignition. If I
> put a finger on the ignition cylinder, I can feel a very faint vibe that
> matches the frequency of the overall drum sensation. But there's no
> feedback in the steering or anywhere else.
>
> No work has been done on it, it's not had any accidents, nothing has
> changed.
>
> I'm at wits end trying to figure it out. I'd welcome any suggestions.
>
> Thanks to all!
>
>
>

Following up....

Found the problem. Front wheel bearing was shot. It was odd that there
were no driving symptoms and no change in/out of 4wd. But it's fixed
now and quiet as ever.

-clappie

Clap Trap wrote:
> Following up....
>
> Found the problem. Front wheel bearing was shot. It was odd that
> there were no driving symptoms and no change in/out of 4wd. But it's
> fixed now and quiet as ever.

Thanks for the follow-up. Glad you found the problem before it got worse.

You don't get driving symptoms from a failing bearing till you see the
wheel bounce off into the distance. :/ The amount of wear that can make
noise is no where near the amount you can feel simply by rocking the wheel.
Guess it's similar to the squeaky idler pulley, but at least there you can
get a stethoscope on it.

--
DougW

DougW wrote:
> Clap Trap wrote:
>> Following up....
>>
>> Found the problem. Front wheel bearing was shot. It was odd that
>> there were no driving symptoms and no change in/out of 4wd. But
>> it's
>> fixed now and quiet as ever.
>
> Thanks for the follow-up. Glad you found the problem before it got
> worse.
>
> You don't get driving symptoms from a failing bearing till you see
> the
> wheel bounce off into the distance. :/ The amount of wear that can
> make noise is no where near the amount you can feel simply by
> rocking
> the wheel. Guess it's similar to the squeaky idler pulley, but at
> least there you can get a stethoscope on it.

Just a comment for future reference but sometimes you can diagnose a
wheel bearing problem by noting whether the noise changes in turns.
Turn left and the right side bearings get loaded a little more, turn
right and the left side bearings do, and the changing loading may mean
that the noise or vibration changes.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

J. Clarke wrote:
> DougW wrote:
>> Clap Trap wrote:
>>> Following up....
>>>
>>> Found the problem. Front wheel bearing was shot. It was odd that
>>> there were no driving symptoms and no change in/out of 4wd. But
>>> it's
>>> fixed now and quiet as ever.
>> Thanks for the follow-up. Glad you found the problem before it got
>> worse.
>>
>> You don't get driving symptoms from a failing bearing till you see
>> the
>> wheel bounce off into the distance. :/ The amount of wear that can
>> make noise is no where near the amount you can feel simply by
>> rocking
>> the wheel. Guess it's similar to the squeaky idler pulley, but at
>> least there you can get a stethoscope on it.
>
> Just a comment for future reference but sometimes you can diagnose a
> wheel bearing problem by noting whether the noise changes in turns.
> Turn left and the right side bearings get loaded a little more, turn
> right and the left side bearings do, and the changing loading may mean
> that the noise or vibration changes.
>

Another give away is your brake pedal. If your brake pedal is lower on
the first pump after taking a corner, your wheel bearings are fried.
That is how we figured out ours was gone. Ours didn't make noise.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

Mike Romain wrote:
> J. Clarke wrote:
>> DougW wrote:
>>> Clap Trap wrote:
>>>> Following up....
>>>>
>>>> Found the problem. Front wheel bearing was shot. It was odd that
>>>> there were no driving symptoms and no change in/out of 4wd. But
>>>> it's
>>>> fixed now and quiet as ever.
>>> Thanks for the follow-up. Glad you found the problem before it got
>>> worse.
>>>
>>> You don't get driving symptoms from a failing bearing till you see
>>> the
>>> wheel bounce off into the distance. :/ The amount of wear that can
>>> make noise is no where near the amount you can feel simply by
>>> rocking
>>> the wheel. Guess it's similar to the squeaky idler pulley, but at
>>> least there you can get a stethoscope on it.
>>
>> Just a comment for future reference but sometimes you can diagnose a
>> wheel bearing problem by noting whether the noise changes in turns.
>> Turn left and the right side bearings get loaded a little more, turn
>> right and the left side bearings do, and the changing loading may
>> mean that the noise or vibration changes.

Not a bad check. Worth noting for the next time someone asks.

> Another give away is your brake pedal. If your brake pedal is lower
> on the first pump after taking a corner, your wheel bearings are
> fried. That is how we figured out ours was gone. Ours didn't make
> noise.

interesting ideas. I'd imagine if the bearings were out enough to
walk the pads back that you could almost feel the bearing move by
rocking the tire or hear it with a stethoscope.

I've had folks say that dragging the brake will make the noise stop for
bad bearings, but that also stops noise from the whole drivetrain.
Especially CV/UV joint noise by loading the joint up.

--
DougW

DougW wrote:
> Mike Romain wrote:
>> J. Clarke wrote:
>>> DougW wrote:
>>>> Clap Trap wrote:
>>>>> Following up....
>>>>>
>>>>> Found the problem. Front wheel bearing was shot. It was odd that
>>>>> there were no driving symptoms and no change in/out of 4wd. But
>>>>> it's
>>>>> fixed now and quiet as ever.
>>>> Thanks for the follow-up. Glad you found the problem before it got
>>>> worse.
>>>>
>>>> You don't get driving symptoms from a failing bearing till you see
>>>> the
>>>> wheel bounce off into the distance. :/ The amount of wear that can
>>>> make noise is no where near the amount you can feel simply by
>>>> rocking
>>>> the wheel. Guess it's similar to the squeaky idler pulley, but at
>>>> least there you can get a stethoscope on it.
>>> Just a comment for future reference but sometimes you can diagnose a
>>> wheel bearing problem by noting whether the noise changes in turns.
>>> Turn left and the right side bearings get loaded a little more, turn
>>> right and the left side bearings do, and the changing loading may
>>> mean that the noise or vibration changes.
>
> Not a bad check. Worth noting for the next time someone asks.
>
>> Another give away is your brake pedal. If your brake pedal is lower
>> on the first pump after taking a corner, your wheel bearings are
>> fried. That is how we figured out ours was gone. Ours didn't make
>> noise.
>
> interesting ideas. I'd imagine if the bearings were out enough to
> walk the pads back that you could almost feel the bearing move by
> rocking the tire or hear it with a stethoscope.
>
> I've had folks say that dragging the brake will make the noise stop for
> bad bearings, but that also stops noise from the whole drivetrain.
> Especially CV/UV joint noise by loading the joint up.
>

One bad thing about those flat bearings is the wheel doesn't rock when
they get loose like tapered bearings do, it just slides in and out.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

DougW wrote:
> Mike Romain wrote:
>> J. Clarke wrote:
>>> DougW wrote:
>>>> Clap Trap wrote:
>>>>> Following up....
>>>>>
>>>>> Found the problem. Front wheel bearing was shot. It was odd that
>>>>> there were no driving symptoms and no change in/out of 4wd. But
>>>>> it's
>>>>> fixed now and quiet as ever.
>>>> Thanks for the follow-up. Glad you found the problem before it got
>>>> worse.
>>>>
>>>> You don't get driving symptoms from a failing bearing till you see
>>>> the
>>>> wheel bounce off into the distance. :/ The amount of wear that can
>>>> make noise is no where near the amount you can feel simply by
>>>> rocking
>>>> the wheel. Guess it's similar to the squeaky idler pulley, but at
>>>> least there you can get a stethoscope on it.
>>> Just a comment for future reference but sometimes you can diagnose a
>>> wheel bearing problem by noting whether the noise changes in turns.
>>> Turn left and the right side bearings get loaded a little more, turn
>>> right and the left side bearings do, and the changing loading may
>>> mean that the noise or vibration changes.
>
> Not a bad check. Worth noting for the next time someone asks.
>
>> Another give away is your brake pedal. If your brake pedal is lower
>> on the first pump after taking a corner, your wheel bearings are
>> fried. That is how we figured out ours was gone. Ours didn't make
>> noise.
>
> interesting ideas. I'd imagine if the bearings were out enough to
> walk the pads back that you could almost feel the bearing move by
> rocking the tire or hear it with a stethoscope.
>
> I've had folks say that dragging the brake will make the noise stop for
> bad bearings, but that also stops noise from the whole drivetrain.
> Especially CV/UV joint noise by loading the joint up.
>

This one gave no symptoms other than noise. No change during braking,
cornering, 4wd, or anything else.

Sometimes you can also tell a bad wheel bearing by going over
"dippity-dos." You know - those times when you top a narrow hill and
your stomach flies up. When you do that, you take load off the wheels
and the sound can change. But that didn't work this time either.

The bearing was actually found by accident. I knew the axle u-joint
needed replacement since it "hopped" in tight parking lot maneuvers.
The bearing was discovered when replacing the u-joint.