Skip to content

The drive axle howls, background noise in the differential gear

Main Causes::

1) Insufficient oil level

  • The drive gear sealing ring is damaged.
  • The sealing rings of the semi-axles are damaged.
  • The breather is damaged or dirty.
  • The filler or drain cap is leaking.
  • The differential cover is leaking.
  • The seal is damaged.

2) Dirty transmission oil

  • Too much water and (or) dirt got into the oil.

3) The final drive reducer or differential gear is damaged.

  • A large gap in the drive gear bearing
  • Poor alignment or gear wear.
  • Difficult movement of the balance wheels on the axle.
  • Scratches on the working surface of the pinion axle.
  • Jamming of the gears or semi-axles in the differential housing.
  • An irregular gap between the teeth of the differential gear.

4) Wear of semi-axle bearings.

5) Wear of spline connection with half axle gears.

6) The semi-axles are deformed or have an unacceptable runout.

7) Loosening of the fastening screws in the axle reduction gear housing, the fastening nuts of the driving gear, the fastening of the driven gear or misalignment.


1) Operation of a vehicle with insufficient level of transmission oil leads to excess heating and consequent rapid wear of bearings and gears of the reducer and differential gear. When the drive axle wears out, background noises arise in various operating modes. In order to eliminate such wear, one should first confirm and eliminate the cause of the leakage. If the leakage is caused by loss of elasticity or insignificant wear of the sealing rings of the drive gear or semi-axes, it is recommended to add SEALER — the agent for elimination of leakages in transmission units in transmission oil, because such solidifying agent can restore elasticity of sealing rings and eliminate leakage . If leakage occurs because of a damaged breather, leaking caps, damaged gaskets, or leaking differential cover, such causes should be eliminated by replacement or repair. Further, after eliminating the causes of leakage and adding oil to the required level, it is recommended to add one of the XADO Revitalizant® solutions for gears and reducers to transmission oil to eliminate wear of bearings and gears.

annotation: When the wear is approaching the wear limit or when the efficiency of application of the XADO Revitalizant® solution for gears and reducers is not sufficient after the mileage of 3,000-5,000 km, it is recommended to use XADO repair lubricant in the amount not more than 2% additionally enter the oil pan into the heated transmission oil.

2) If a large amount of dirt and moisture gets into the transmission oil, bearings and toothed gears can quickly wear out even with insignificant mileage. In this case, it is recommended to change the transmission oil, rinse the axle interior and treat the fresh transmission oil with one of the XADO Revitalizant® solutions for gears and reducers.

3) If the final drive reducer is damaged, all fully worn components should be replaced and gaps adjusted properly. After readjusting the repaired reducer and running it in for a short time (100-300 km), for further protection against wear it is recommended to treat the axle with one of XADO Revitalizant® solutions for gears and reducers if there are no assembly defects.

Such solutions are suitable for all the situations described:

4) In the event of critical wear, the half-axle bearings should be replaced.

5) In case of critical wear, the splined shaft connection with half-axle gears should be changed.

6) Loosening of the fastening screws in the axle reduction gear housing, the driving gear fastening nuts, the driven gear fastening or its misalignment can be corrected by tightening them to the recommended torque.

Previous article Vibrations during engine operation
Next article Difficulty starting (petrol engine)