Is your car making strange noises when you’re driving? Does it whine when you accelerate or slow down? If your car whines, grinds, howls, knocks, or clunks, you could be dealing with a bad front or rear differential. Today, we will discuss all the causes for this issue and show you how to fix a noisy differential.
By the end of the article, you will understand what differentials do, what the different noises mean, how to diagnose a bad differential, and how to quiet a noisy differential whine so you can have quiet rides once again. Without further ado, let’s get started!
What Is a Differential and What Is Its Purpose?
When you turn your car, the outside wheel has to travel faster than the inside wheel. The differential is part of the rear and/or front axle assembly and it’s a set of gears. Their purpose is to transmit engine power to the wheels while allowing them to rotate at different speeds whenever you turn left or right.
This allows the wheels to either provide traction so they rotate less or react to resistance. Front-wheel-drive vehicles feature the differential alongside the transmission, inside a unit called a transaxle. In rear-wheel-drive vehicles, you can find the differential between the rear wheels and it’s connected by a driveshaft to the transmission.
In all-wheel-drive and four-wheel-drive vehicles there’s a center differential or transfer case that will distribute power to the front and the rear. If you want to learn more about differentials, click here to read more about this important car part.
What Causes Differential Whine Noise?
Differentials are finely tuned, so they rarely need to be repaired. However, if you’re experiencing front differential noise or rear differential noise, it means there’s something wrong with the differentials.
Now, the differentials can fail for many reasons and you must become familiar with them. The kind of noise your car is making will help you identify the underlying cause, but you have to know what you’re looking for.
The first step on how to fix a noisy differential is to know what the noise means, so here’s a list of noises and their causes so you can have a clear idea of what’s going on with your differentials.
Differential Humming Noise
If you’re dealing with a humming noise or a whine, it could mean that there’s excessive clearance with the ring gear.
Clicking Differential Noise
If you hear a clicking noise when you slow down from 20 mph to stop the car, it may mean there’s an issue with the side-gears, or the carrier care bores are worn out. But if you hear a clicking or clunking noise every few feet, you may be dealing with a broken ring gear or tooth on a pinion.
Grinding Differential Noise
If you hear a grinding or squeaking kind of noise when you’re driving, it could be due to a worn or damaged universal joint.
Whirring Differential Noise
If you hear a whirring noise when you’re speeding up or slowing down at 10 mph, it could mean that the pinion bearings are either loose or worn.
Knocking Differential Noise
When you have a gear tooth that’s chipped or a worn axle shaft splines, you will hear a knocking or clicking kind of noise from your differential.
Rumbling Differential Noise
If you hear a low-pitched rumble when you’re driving at over 20 mph, it could mean that the carrier bearing is wearing out. If you hear a rumbling or clicking kind of noise that gets worse when you make hard turns, it could be a sign of a worn wheel bearing.
Clunking Differential Noise
If you hear a clunking or banging noise whenever you corner, reverse, or slow down quickly from highway speeds, it may mean the spider gears or clutches are worn out or your differentials may need proper lubrication. Incase you hear the noise when you speed up, it could be because of a loose or worn yoke spline, spider, or U-joint wear. If it happens when you’re starting from a stop, the slip yoke splines may be worn.
Banging Differential Noise
If you hear a banging, crunching, or popping noise when you corner, it could be due to damaged or worn-out spider gears. It could also be because of damaged or broken teeth in the pinion gears, which make a banging noise every 2 to 3 feet when you accelerate or slow down. If you hear this noise every 8 feet, you could have broken teeth or damaged ring gear.
Whining Differential Noise
When you hear a whine or a howl whenever you accelerate or slow down, it may be because there’s a loose gear inside your car’s differential.
Howling Differential Noise
If you hear a howl when you slow down the car, you could be dealing with a bad pinion bearing. Incase you hear the same noise when you accelerate, it could be due to a lack of lubrication or overloading. If the howl is accompanied by a whir or a rumble when you accelerate, you could have a worn gear set, pinion, ring gear, or bearings.
Differential Noise When Turning
If you are steering at any speed and you hear a noise with a steady pitch or intensity, it could indicate an issue with the meshing of gears inside the car’s differential. If the pitch increases or becomes more intense when you corner, then there could be an issue with the wheel bearing.
If what you feel is a vibration throughout the vehicle, the issue could be a worn U-joint or a driveshaft that’s out of balance. If the vibration intensifies when you’re driving at a particular speed or when you slow down, it could be because of a misaligned pinion gear.
How to Diagnose a Differential Noise
Learning how to diagnose a differential noise is key when you’re learning how to quiet a noisy differential whine. However, diagnosis can be a bit problematic because it’s not easy to tell the difference between a failing wheel bearing and a differential that needs attention.
- Take the Car Out for a Spin
Both of these issues can make the same type of noise and similarly affect your driving. So, the first thing you need to do is take your car out for a spin on an empty road at a steady speed of 50 mph.
Listen very carefully when you accelerate to see if there’s a howling noise. Turn the wheel slightly to the left and then to the right while listening intently. If there’s a noise, determine if it stays the same or if its intensity changes.
If the noise increases when you steer left and decreases when you turn right, the most likely issue is the wheel bearing. But if the noise doesn’t change when you steer to either side, you could be dealing with a front differential noise or rear differential noise.
- Put the Car on Jack Stands
If you think you have a failing differential on your hands, you should put your car on jack stands or a hoist. You want your drive wheels to be lifted off the ground and put blocks behind the other tires. Shift into neutral with the engine off and rotate one wheel forward or back.
Most cars feature an open differential, so when you do this, the other wheel should rotate in the opposite direction. If both tires rotate in the same direction it means you don’t have an open differential or there’s a problem with the differential.
Get someone to help you by holding one wheel in place or use a block to keep it from rotating. While in neutral, you will be able to rotate one drive wheel while the other is kept in place. If you can’t, it means there’s an issue.
Next, you want to make sure the wheels can rotate freely and start the engine. Disable your ABS/ESP system and shift into forward drive gear while the engine is idle.
Listen to the differential; if it’s quiet, you’re good, but if there’s a noise, it means something’s failing. Refer back to the types of noises and what they mean for more understanding. If the differentials are quiet but you hear a noise from one of the drive wheels, it means the issue is not with the differentials, but with the wheel bearing.
Symptoms of a Bad Front Differential
Usually, when a front differential is going bad, there are 4 tell-tale symptoms. If you notice one or more of them, take your car to the mechanic right away and don’t wait too long. If you do, your car could be damaged and it will be more expensive to repair.
- Your Car Goes Through Too Much Oil
If your car is going through oil too quickly or it’s leaking oil, it means your differential is not getting the lubrication it needs, so it will start to fail. The oil keeps the mechanism from overheating and allows it to run smoothly. If it’s not getting the oil it needs, it will lead to a front differential noise, like a whine or a howling.
- Grinding Differential Noise
If you’re hearing a grinding noise, it means your front differential is going bad, so you should get your car checked out as quickly as possible. The noise will get louder as you accelerate and this noise is often related to a loss of oil as well.
- Your Tires Wear Out Fast
If your inner tire is wearing out quicker than the outer one, it means your front differential is not doing its job. Remember, the differential manages the speed at which the tires spin when you are cornering. So, when they go bad, the inner tire will wear out faster.
- Vibration When You Accelerate
Lastly, if your car starts to vibrate when you accelerate, that’s a clear sign that you may need to replace the front differential. When you accelerate, the vibrations will increase and you’ll feel it in the driveshaft.
Symptoms of a Bad Rear Differential
When your rear differential is going bad, there are 5 symptoms you should keep an eye on. If you are experiencing one or more of these symptoms, take your car to a mechanic and have it checked out as soon as possible.
- Rear Differential Noise
One of the most common symptoms of a bad rear differential is excessive noise. If you hear a humming, whining, howling, or whirring noise and it changes whenever you accelerate, slow down, or corner, you may be dealing with a failing rear differential.
- Oil Leaks
If you see there are leaks around the gasket of the rear differential or the rear axle area, it means your differentials are not getting the lubrication they need. When the leak is bad, it will lead to an accumulation of oil and dirt below the carrier, brake system, and pinion gear.
- The Differential Is Overheating
If your rear differential is overheating, it means there’s a problem. It could be a lack of lubrication, overloading, worn gears, and more. Usually, when there’s overheating, it means that there’s not enough differential fluid.
- It’s Challenging to Handle the Wheels
If you are having difficulty handling your wheels, particularly when you’re cornering, it means your rear differential has an issue. In most cases, it means that the differential is worn out and it’s dangerous to drive your car like that, so make sure you solve the issue quickly.
- Vibration From the Rear Wheels
Vibration is always a cause of concern, but if it’s coming from the rear wheels, you should get your rear differential checked out because there could be something wrong. Vibrations are always a sign of trouble, so don’t ignore them no matter where they’re coming from.
How to Fix a Noisy Differential: Solution for Front and Rear Differential
If you are wondering how to fix a noisy differential, you will be happy to know that this is something you can do on your own. Especially if you have mechanical skills and the right tools, such as jack stands or a hoist, which is a must.
The moment your differential starts to make a noise, you know repairs are inevitable and they should be done quickly. The longer you wait, the more you’ll spend on repairs. So, here are the steps to follow to fix a noisy differential so you can get started.
Step 1: Prepare Your Car and Work Area
The first thing you have to do is prepare your car and work area. Place your car on a jack stand or ramp so you can access the differentials and see what they look like. Something to note here is that differentials are available in different designs depending on your car, so the repair job can be very messy or super tidy.
Step 2: Change the Differential Fluid
Once you have access to the differential, the first thing you should do is replace the differential fluid. Check your car’s manual for instructions on how to do this properly. If it has been a while since you changed the differential fluid and there aren’t any leaks, you should drain the oil before you pour the new fluid.
If your differential has a drain plug, you’ll just have to remove the fill-hole plug at the top and unscrew the plug. However, if you have to remove the differential housing, you should remove some bolts and loosen up the rest so the cover is still in place.
Pry it over with a screwdriver and be gentle, so you can drain the fluid and inspect it to make sure there are no metal pieces in there before you pour the new differential fluid. Also, make sure you get the right differential fuel for your vehicle.
If you need visual guidance to remove the differential cover, this detailed video will help you out!
Step 3: Replace the Differential Seal
If you found metal pieces in the oil you drained from the differential, you have to remove the differential cover entirely, clean it, and inspect it carefully. You may need to replace the seal, especially if you’ve been dealing with a loud whine when you drive.
The differential seal should be replaced whenever there’s a leak, so if your car has left oil stains on your parking spots, it means that the differential seal is broken.
You’ll have to place your car on a jack stand and go with a hydraulic lift so you can do this job easily. Not to mention you have to remove the wheels, tires, and axle, so you’ll need 3 to 5 hours to do this. Here’s a step-by-step guide you can use to replace the differential seal.
Step 4: Go on a Test Drive
In most cases, a change of differential fluid and seal replacement will eliminate a noisy differential whine. So, once you do this, you should go on a test drive. If you don’t hear any whining noise, you won’t need to perform any more repairs. However, if the whining is still there it means there’s an issue with the parts.
That means you have to inspect all the parts of the differential, including the pinion seal, side seals, and rear gasket. The latter is not difficult to inspect, but the other parts may be a bit tedious and challenging.
To inspect the rear differential, all you have to do is drain the oil and check if it’s broken or worn out. To inspect the side seals, you’ll have to remove the axle shaft. If you don’t know how to do that, you can look for videos for your specific make, model, and year, or check out the owner’s manual.
Once you remove the axle safely, look for broken seals. If you find one, don’t remove it until you stuff a clean rag in there to protect the differential once the seal is removed.
Step 5: Replace Any Broken Parts
When you’re trying to fix a noisy differential, you may have to replace broken parts such as seals, gears, bearings, etc. This video will help you inspect the differential gears for wear and if you find that they are chipped or worn, you’ll have to replace them.
If you have to replace the bearings, you’ll have to take the differential apart and also replace pinion seals. Whatever it is that you have to replace, make sure you get the right parts and do your research to do the job well. If you find it too overwhelming, take your car to a professional mechanic.
Step 6: Lubricate Everything
Once you replace old or broken parts, make sure to lubricate everything well and don’t forget the differential fluid. Pay special attention to the axle and make sure all the gears are well placed and rotating smoothly.
When you are certain that everything is lined up, you have to tighten the bolts and attachments so you can put the axle back into the differential. Take your time and do it well.
Step 7: Go on a Test Drive Again
When the axle is in its place, the bolts are tightened, and everything is reassembled once more, it’s time to go on a test drive. Drive for 15 miles and if everything’s okay, you shouldn’t hear any noises.
Once the test drive is done, check the differential again and make sure there are no fluid leaks. If there are, you have to check the differential seal and take care of it if need be as explained in step 3.
Step 8: Clean the Differential Housing
If you’ve replaced all the parts that needed replacing and you’ve changed the differential fluid but your car still whines, it could be due to a dirty differential housing.
Cleaning the housing is very easy to do and you’ll just need a clean rag and brake cleaner. You want to use the brake cleaner to saturate the male fitting and axle gear before you wipe off all the grease and dirt.
If the noises persist even after all this, you have to take your car to a mechanic ASAP. Let them know about the repairs you’ve performed and explain the kind of noise the differential has been making.