Buying and Maintaining Diesel Cars

Posted on: 8 May 2017

Most people don't understand what the purpose of a differential is, or even if they have one. Unless you're looking at a vehicle designed for off-road use, manufacturers don't tend to talk about the differential when they're trying to make sales, but that doesn't mean it isn't a very important component.

What you need to remember is that wheels actually spin at slightly different speeds. The job of the differential is to distribute the torque created by your engine between two parallel wheels. Most vehicles contain only one differential, though others may include them at both the front and rear.

In any case, differential issues are commonly diagnosed by odd sounds made while you're driving. Here's a quick roundup of the sounds you should watch out for and what they might mean as far as differential repair.

Howling

Howling is one of the more common sounds an unwell differential might make. This is most often caused by low or dirty oil. The differential contains a lot of gears and moving parts, so it can howl loudly when it doesn't receive proper lubrication, and that sound may become louder as your vehicle increases its speed. If your differential howls under all kinds of acceleration, it could also be that the gears have become worn or that they have moved out of alignment with each other.

Banging

If you notice banging sounds, you're probably dealing with a more serious problem; banging usually means that something has actually broken instead of simply becoming worn. If one of the gears breaks, you'll probably hear a crunching or banging sound when you start moving. It might also be that a broken ring gear is banging or grinding instead of properly engaging with the pinion; if this is the case, you're likely to find that bangs or clunks are heard regularly instead of continuously as you drive. Finally, one of the gear teeth might have been chipped; this will produce bangs, but only when you're speeding up or slowing down.

Whistling

A high-pitched whistle is often the first sign of differential trouble. Unfortunately, the fact that it will not be that loud means that people often fail to hear it. If you do think you hear a whistling sound, turn off your radio and concentrate to see if it's really there. Whistling will usually be caused by a slightly worn ring or gear. As the problem gets more serious, you'll start to notice louder whirring noises at higher speeds.