I had a "roaring" noise in front end. It was diagnosed as a left wheel bearing. Assembly was replaced. Noise continues. When vehicle while in motion is turned to left noise stops. A second mechanic feels that it is the right wheel bearing. First mechanic disagrees. His reason: right assembly turns freely after it has been removed. His second diagnosis: a faulty bearing in the front differential. Says that to replace this bearing is expensive because you have to "drop the differential" to repace bearing.

Can you determine the condition of the bearings in front wheels by turning the assembly (bearings are enclosed) after it has been removed from vehicle?

Does one have to drop the front differential to repair a bearing.