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Whirring

S

sjx40250

NAXJA Forum User
Location
Alexandria VA
I now have a whirring sound coming from somewhere on the drive train. It increases in frequency as the speed increases or decreases with speed as well. Can't detect where it is coming from
I put the heep on jackstands and put it in drive and 4wheel drive for both axles but could not hear the whirring. Only exists when driving on the road.
I checked fluids in the front and rear diff as well as the TC. Didn't check the transmission though.
1998 4.0L AW4 30 front, 8.25 rear. Stock.

Any speculation where to start or how to determine what is causing the noise?
 
Pull the front DS, drive it and see what you hear.

("see" what you "hear"?)
 
Whirring? or groaning/moaning? Check the condition and level of you P/S fluid. I had a groan, moan, whirring. Needed P/S fluid, went away. Maybe.
 
Not tires, they haven't changed.
Power steering changes with engine speed not vehicle speed.
Not groaning/moaning - know that one well!
Will have to pull the frnt DS, didn't really want to do that until I got some responses. - Thanks all.
I suspected wheel bearing too. I have cheep automotive stythescope I used to check the rear wheel bearing and diff housing. I could hear them but they were all consistant in noise level and sound. I forgot to check the front. Guess I will do that again prior to removing the DS. It does sound much like an electric window regulator or a straight cut gear set. The sound becomes noticable above 15 MPH. Just showed up last week.
 
Could be a transfer case chain.
 
So I put it back on the jackstands, turned it on, but it in 4hi full time and put it in drive. Forgot to release the ebrake. The whirring was clear!

Disconnected the DS, still heard a whirring but at a higher frequency. Couldn't really tell if it was the same thing. More noise in 4Hi FT than any other selection.

Dropped it down and drove it around the block. Whirring still evident but like on the jackstands. Did vary with speed and consistant.

Checked the AW4 fluid level, between add and full. Must be either the AW4 output shaft bearing or the TC.

Recommendations? Should I just drive it? I did replace the TC fluid with Dex III soon after hearing the whirring.
 
Personally, I would run it and just monitor things.

It is either going to get worse fast, or get worse slow, or stay the same, or go away.

If it gets worse it will be easier to locate the source.

Good luck.
 
Joe, that was my thinking too.

I had a friend years ago who said "if it came by itself, it will go away by itself". That has held true! It either goes away quietly or with a bang!
 
I have the same rear axle and i experience said whirring sound when i put it into "1" gear on the auto. So it might be a load thing or fluid, or your gears are not meshing properly.
 
Not sure if it's come up yet, but if you just can't find where it's whirring from, you might also try disconnecting the rear driveshaft and inspecting the u-joints. I've had u-joints that went dry before they developed play, and you couldn't tell from the usual shaking and wiggling until they were actually disconnected. But they'll make noise.
 
Jeepcherokeeboy99 said:
u-joints
Click to expand...

Matthew Currie said:
Not sure if it's come up yet, but if you just can't find where it's whirring from, you might also try disconnecting the rear driveshaft and inspecting the u-joints. I've had u-joints that went dry before they developed play, and you couldn't tell from the usual shaking and wiggling until they were actually disconnected. But they'll make noise.
Click to expand...

;)
 
another update:
I went on a trip today and did the following.
Put the transmission in neutral - no impact.
Put the TC in neutral - no impact.
Now if the transmission was contributing, I would not expect to hear the sound with the TC in neutral as all the load should be removed. Do you agree?
When the vehicle was on the jackstands and in 4 HI and the e-brake on, no rear drive shaft rotation, the noise was deffinitely there.
With the e brake off, it was hard to hear it. I am wondering if the ebrake produced enough load to induce the sound and that it is in the transfer case with rotating parts on the drive line side of neutral.
 
Given that the sound is only associated with the vehcle in motion and even with the TC in neutral, anything in front of the input shaft of the TC, including the shaft, is not a contributor. That leaves the chain to the front drive shaft, the TC oil pump and the speedometer gears as suspect if the TC is the source.
What would then be eliminated are:
Engine
Transmission
Input to the TC
Rear drive shaft to the wheels (e-brake applied prevents rotation and the sound is still present while on jackstands).
Front drive shaft to the wheels (disconnected drive shaft resulted in no noise or undetected noise level).

What is not eliminated is the TC output.

No impact to MPG as I went on a 60 mile trip with a 21 MPG average.

I have an 1989 TC (242). Other than the input and rear output shafts, are they identical?

Any comments? Like yeah, that makes sense?
 
Last edited:
take a video of the sound so we can hear it
 
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