The differential is an important part of the car. It is what enables wheels on the same axle move at different speeds, and this is particularly important when taking turns. When negotiating a corner, the outer wheel needs to spin faster than the inner one, because the outer one moves across a longer distance.
The differential is made up of a bunch of spiders and gears and can be pretty complex. A rear noise is a sign that the synchrony of these gears is not at its optimum. You need to know how to identify these noises and know exactly what's wrong. That's the only way you can find a suitable solution for it. So here's a brief overview of some common causes of differential noise.
Leaking differential fluid
Sometimes, the seals at the rear axle fail, and the differential fluid leaks out. Check the rear for any leaks and watch out for distinctive smells. You could also inspect the ground the car has been on. If you notice a leak alongside the noise, then you're probably suffering from this problem. In some cases, the leak may be difficult to spot as the fluid may seep into the brake assembly. Such leaks are normally associated with an increased braking distance. Axle oil is also thick and hardly flows out of any openings when cold. You'd be in a better position to spot leaks on the axle, inner surfaces of the wheels, or brakes after warming up your engine. Get the car to a repair shop for a differential oil change and refill.
Incorrect ring and pinion gears
These are the gears that make up the differential. The pinion gear is what causes the ring gear to turn once the drive shaft starts rotating. In summary, this is the basic make-up of the differential. Once these gears are not properly installed, then the contact between the teeth is affected. The teeth between the gears exert too much heavy contact with each other and cause the noises.
Worn out gears
Another cause of a noisy rear end is wearing out of gears. This is probably the case of your vehicle has seen better days and clocked thousands of kilometers. The sound produced will be a howling noise when accelerating. Such gears need to be replaced and lubricated to get rid of the noise.
The howling noise could also be caused by worn out bearings that may need replacement. The bearings may also produce a rumbling sound if they are in bad shape. For assistance, talk to a a diff repair expert.