A small rear differential leak or a slight bearing whine is sometimes tempting to ignore.  A proper repair involves disassembly of the differential and replacement of the worn parts.  Doing nothing is far more expensive.

There are many possible causes of differential problems.  Water sometimes dilutes the lubricant.  Other times the rear differential oil is not replaced and over time breaks down.  Still other times a bearing will fail and cause a seal to leak and/or ring and pinion gear misalignment.

Rear end differential gears operate at extreme pressure.  A misalignment of a few thousandths of an inch can quickly destroy ring and pinion gears.  When the pinion bearing in the above photo began to fail, it was due to a breakdown of the rear axle lubricant.  The differential oil had not been replaced in over 150,000 miles.  

Replacement of the bad bearing and the differential oil may have bought several additional years of service.  Instead the vehicle was driven a few months with the bearing noise.  Eventually the load became too great and the ring gear failed.

The broken teeth jammed, tore the rear cover and locked the rear differential.  In seconds, a few hundred dollar repair became a few thousand dollar repair and a wrecker bill.

Rear differential leaks and noises can normally be repaired if address immediately.  Better still they can often be prevented with proper maintenance.  Doing nothing is a VERY expensive option . . .

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