To understand how you can tell if your car's differential may have a problem, you have to first understand how a differential works. Essentially, it is a piece of technology that allows two wheels on the same axle to turn at different speeds. Why would you want your tires to turn at different speeds? Consider how your wheels work when you go around a corner. The tires on the outside of the turn have to travel farther than the ones on the inside. This means they have to turn faster. If they don't, and both tires spin at the same speed, the inner tire will spin in place as it pivots.

Signs of a Problem

The differential is a vital component of your drive train and linked closely to the transmission. It's here that you will see the first signs of a problem. During acceleration and slowing of the vehicle, there will be strange noises coming from the drive wheels (from the front if you have a FWD or the rear for RWD). There may be an increase in noise when you merge onto a highway or have to brake suddenly. This is because the gears in the differential are starting to wear and aren't meshing as well.

Another sign that your differential should be looked at is a strange vibration that you can feel through the floor of the car when you're traveling at highway speeds. This vibration is caused by improper lubrication of the differential as the gears slip in and out of alignment. If you see any fluid pooled under your drive shaft overnight, this is another big indicator that you have a leak in either a universal joint or in the differential.

How to Fix It

Because of the degree of difficulty involved, properly diagnosing a differential problem isn't something for the casual maintenance person. If you're worried about whether or not your differential is going bad, you need to take your car to a licensed mechanic right away. They will be able to do an inspection of the gears and fluid to tell you if there's an issue. In many cases, all you'll need to set everything right is a fluid change. In more extreme cases, you'll need the seals replaced or even an entire transmission rebuild. This is why it's so important to adhere to your manufacturer's recommended fluid maintenance schedule and change your differential oil every 30 to 50 thousand miles.

As always, there is nothing wrong with just taking your vehicle to a mechanic, such as those found at Jim Stephen's Foreign Car Repair, if you aren't sure what the problem is.