Front Axle Growl Noise in 2WD May Not Occur in 4WD - keywords differential drone moan

This PI was superceded to remove model years due to an engineering investigation. Please discard PIP3853A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Customers may comment of a moan, drone or growl noise from the front of the vehicle. The condition may be described as a noise that phases (cycles) in and out. The noise typically occurs in 2WD and is eliminated when shifted to 4WD.

The condition described above may be caused by several different concerns. Make sure to see the notes below prior to any differential diagnosis.

Note 1: Make sure the noise is not coming from the rear brake drum rubbing the backing plate as this noise can sound very similar to this front axle concern. Refer to the latest version of PIT3224.

Note 2: Also refer to the latest version of PIT3876 as body mount ground out has contributed to this concern.

Inspect the front axle disconnect sleeve (shift collar) item #21 for proper installation.

There could be machining a burr on the counter bore of either stub shaft in the front axle that would cause scraping on the pinion shaft (right) or inner axle shaft (left). Deburr the stub shaft counter bore and replace any damaged mating components.

Check the bearing assembly (item #22 Document ID # 1285562) and the bearing side of the left front axle shaft (item #23) for rust. Clean or replace the bearing assembly as necessary. Pack the bearing assembly with synthetic bearing grease.

It has been discovered that simply removing and reinstalling the front differential assembly has corrected this noise. If no obvious signs of damage are found, the vehicle may be repaired once the front axle is reinstalled.

Road test to ensure the noise is eliminated.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.