5 Leaking Differential Symptoms and How to Fix

A leaking differential can lead to a broken differential. A broken differential can lead to expensive repair or replacement costs and even dangerous driving situations! Read on to see the symptoms of a faulty differential and what you can do with a car with a damaged differential. 

5 Symptoms of a Differential Leak

#1 Strange noises

A bad differential sounds much worse than a normally functioning one. If you hear grinding or rattling, especially from the back of your car, it could mean you have rear differential problems. Grinding or rattling coming from the front of your car could also be your transmission, but it is definitely one of the more common bad differential symptoms, and you should definitely have it looked at by a mechanic. 

#2 Strange smells

Differential oil (also called “gear oil”) is thicker than motor oil. This means that when it goes bad, it goes bad quickly, and many bad things can happen to your differential once it goes. Because it’s already thick, when it thickens even more, it heats up, and the gears have more friction, creating more heat. This will cause your differential oil to smell bad. Any time you smell burning coming from your car, it’s time to get it checked by a mechanic because it will lead to bigger issues down the road. 

#3 Poor handling

The differential helps your vehicle handle by keeping the wheels on either side of the axle spinning at the correct speed. (This is true even on the rear axle differential, even though they’re not the wheels steering your car.) If your car isn’t handling correctly, it might be because of a faulty drive differential. 

#4 Vibrations

A differential without sufficient gear oil will cause the gears to mesh together not as smoothly as they should. This will sometimes cause the car to vibrate while driving along, particularly during turns. Vibrations can be a sign of a faulty differential or many other serious issues with your car. It’s definitely time to get your car checked out by a mechanic if you feel vibrations. 

#5 Leaks

Differential oil can leak from the gasket. Sometimes it’s a slow leak (seep), or sometimes it leaks quickly enough to drip. If you suspect an issue with your differential, check for leaks. Read on for how to check for leaks. 

How To Check if Your Differential is Leaking

Every car has a differential (sometimes called a “diff”). A rear-end differential is found on cars that are rear-wheel drive. Front-wheel drive cars have a front-end differential (sometimes called a transaxle). Cars with four-wheel drive have both, which means you’re prone to a rear differential leak as well as front differential leaks. There are two main ways to check for a leaking differential. 

Differential oil under your car

Checking differential fluid should really only be done by a trained mechanic, but you can look out for signs. If you have rear-end differentials, you will find an oil leak under your car’s rear axle. If your front diff is leaking, it’s a bit more complicated because that’s where other leaking fluids from the engine bay will appear as well. If you just find oil on the ground underneath the front of your car, it could be differential fluid, transmission fluid, or motor oil. If you have a front-wheel drive car and find a leak in the ground in the front of your car, have a mechanic check your differential oil. (Especially if you have symptoms of a bad differential, like front diff noises.)

Leaking rear differential gasket

The best way to find a leaking differential transmission is to check around the gasket. You’ll find this on the underside of the differential housing, and if you find oil leaking from it, you have a worn-out gasket. This means your gasket is leaking fluid, and it’s only a matter of time before it turns into a bigger problem. If you have a rear diff leak, you will find the oil drips right in the middle of the two rear wheels. 

What Causes a Rear Differential to Go Bad

The main cause of a differential gone bad is too little gear oil. The gear oil keeps the gears lubricated and prevents them from creating too much friction and heat while the spider gear inside the differential is spinning. This heat and friction will eventually cause the metal gears to grind down and lead to a broken differential. Another cause is just putting it through hard use. If you have modified your car to have more horsepower than it’s designed to have, or you do burnouts or drag racing, it’s a sure way to kill the lifetime of your differential. 

What Can Go Wrong If I Drive With a Bad Differential

What can go wrong while driving with a bad differential depends on how severe the problem is. Vibration isn’t that dangerous or even annoying while driving, but if it’s from the differential, it means it’s time to get it looked at and fixed. If you have badly chipped gear teeth or broken gear teeth, you will experience a skip or slip in power while driving. This gets worse the faster you drive. 

In more severe cases, driving with a faulty differential will create problems with the way your car handles around turns. The tighter the turn, the more you will feel the handling issues. In very extreme cases, a broken differential can even leave you stranded.