I have a '97 F150 4X4 with 4.6 and auto transmission with 83K mi.

There has been a 'howling' noise present for the past 30-40k mi. It's gradually becoming louder and I think I should get it checked.

The noise becomes heard around 30 mph and only while under load. If I remove my foot from the accelerator, the noise goes away. The noise gets louder as road speed increaes, but remains constant regardless what gear the tranny shifts. Installed new tires and the noise hasn't changed. Occurs in both 2WD or 4WD.

Has anyone heard of this? Please direct me to more info. I think it must be differentials, driveshafts, or transfer case but I'd like to know where to start.

Thank you!
- Ken

 

TSB Article No. 99-14-3
NOISE - "MOANING" FROM FRONT DIFFERENTIAL WHILE IN 2-WHEEL DRIVE - VEHICLES BUILT THROUGH 4/15/1999
AXLE - "MOANING" NOISE FROM FRONT DIFFERENTIAL WHILE IN 2-WHEEL DRIVE - VEHICLES BUILT THROUGH 4/15/1999

Publication Date: JUNE 29, 1999

FORD: 1997-99 EXPEDITION, F-150, F-250 LD
LINCOLN: 1998-99 NAVIGATOR


ISSUE:
Some 4X4 vehicles built with center disconnect front axles may exhibit a "moaning" noise from the front differential while operating in 4X2 mode. The noise goes away when operating in 4X4 mode. This may be caused by the front differential side gears.

ACTION:
Replace the front differential side gears with revised gears and replace the front differential pinion gears with revised gears. Refer to the following text for details.

For vehicles that exhibit a front differential moan in 4X2 mode that goes away in 4X4 mode, replace both front axle side gears and both front axle pinion gears. Replace any worn or damaged pinion thrust washers and side gear washers. Refer to Section 205-03 of the appropriate model/year Workshop Manual for removal and installation procedures.

PART NUMBER PART NAME
XL3Z-4236-AA Side Gears (2 Per Box)
XL3Z-4215-AA Pinion Gears (2 Per Box)
DOAZ-4230-B Pinion Thrust Washer
C9OZ-4228-B Side Gear Washer



OTHER APPLICABLE ARTICLES:
NONE

WARRANTY STATUS:
Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage

 

Hi Ken and welcome to FTE
I'd be almost willing to bet that you've got dead pinion bearings in the rear diff.

 

terrible news for me. would anyone like to estimate the difficulty of this job? i'm pretty sure it takes some specific skill and alot of time if you've never done it before. How much would a shop charge for this? And, what are the "side gears"? I guess the front axle doesn't disengage on the ends instead it disengages within the Differential.

 

sorry to bring back an old thread, but did you ever sort out the Moaning situation on your F-150? I'm in this situation right now and I want to know what to do, it's driving me crazy.

 

I had the bearings in the rear diff replaced. The noise got better, but did not go away. I sold the truck 4 months later because the wife needed a minivan. Don't know if the new owner ever resolved this. Sorry I don't have a definitive answer for you. Good luck.

 

Your differential ring and pinion gears are howling.It's not really a do it yourself type of job.