Your car’s brake system relies on a reasonable amount of friction between the brake pads and the rotors to bring the car safely to a stop. Yet the friction never gets serious enough to cause a fire or overheat the metal.
So, when you step on the brakes and you see smoke, you’re only right to be worried. This isn’t a normal thing and left unchecked, it could cause some seriously unsafe and expensive damage to the brake system.
The most likely cause of brake smoke is usually a stuck caliper or perhaps a brake pad that’s come loose from the mounting in the caliper. Warped rotors and brake drag could also be afoot.
To find out what’s causing your brakes to smoke and what you can do about it, we’re going to have to pull over and take a closer look at common brake components and what can go wrong with them.
Is It Normal for New Brakes to Smoke?
New brakes that haven’t been bedded in or cured could still give off a few tiny puffs of smoke if you’re braking hard or you need to ride the brakes down a long, steep hill. Still, this should clear up in a few miles. You might want to think about bedding in your new brakes to marry their smooth relationship with your rotors.
This is a careful process of driving at 35 MPH, then lightly braking down to 5 MPH. Then speed up again to 35. Rinse and repeat 3 to 5 times. Then, take it up to 55 and slow it down to 5 MPH. Rinse and repeat 3 to 5 times. Then, take a leisurely drive home and let the brakes cool all the way down before driving the car again.
7 Causes of Car Brakes Smoking and How to Fix Them
Overheated brakes from abusive braking, caliper problems, and improperly mounted brake pads are the top reasons why brakes might be smoking. However there are certainly other problems that could be afoot if you see smoke every time you put your step on the brake pedal.
Here are seven common causes of smoking brakes and how to fix them.
1. Overheated Brakes
Overheated brakes are often the result of arguably abusive braking habits. This includes stomping down hard on the brakes when you’re coming off a highway or riding the brakes down a long, steep hill. Every time you step on the brakes, the caliper presses the brake pads into the rotors, which creates friction.
The heat energy that builds up can cause the filler, amalgam, and other materials in the brake pads to get superheated to the point where they start smoking. This can also glaze some of the material onto the brake rotors. Once this happens, the brakes can smoke later, even when you’re driving carefully.
How to Fix
Reducing the risk of brake smoking due to overheating starts with reviewing and correcting your driving practices. To begin with, try to honestly assess your driving habits and make an active effort not to drive aggressively.
Driving aggressively and braking hard in stop-and-go traffic can gradually start to overheat your brakes, causing them to smoke. Staying within the speed limit and braking gently in medium bursts will go a long way toward keeping your brake pads within the specified heat range.
Using engine braking when driving down long declines will also help reduce the risk of overheating your brakes. So, as long as your car is traveling under 30 miles per hour, you can use the automatic transmission’s “Low” gear setting to help take some of the strain off your brakes.
Maintaining your brakes will also help reduce the risk of brake overheating. When brake pads start to wear down, the risk of metal-on-metal contact increases between the calipers and the rotors. Even if you have a little brake pad material left, minor metal-on-metal contact will drive up the heat from friction, which can cause the remaining amalgam filler in the brake pads to smoke.
2. Brake Drag
Brake drag from an overfilled brake fluid reservoir can cause the brake calipers to remain partially depressed, causing enough friction to overheat your brake pads and making them smoke. You might not even notice it when you’re driving along; then, when you stop and the air is still, the superheated brake pads start giving off noticeable tendrils of smoke.
Brake drag also makes your MPG suffer, as the torque from the engine and transmission struggle slightly to overcome the friction. You might even notice the engine running hot or at higher than usual RPMs.
Brake drag is a common mistake caused by DIY mechanics who do their own brake jobs and won’t bleed out the lines. The fluid level in the reservoir is the same as it was when you had thin, worn-out brake pads. With thicker new pads installed, the back pressure from the calipers will have the reservoir reading high or even with brake fluid in the neck.
How to Fix
Using a medicine syringe, turkey baster, or a siphon hose to draw out the brake fluid should alleviate the pressure of brake drag on the calipers. The goal is to draw the line in the reservoir down to just a hair under the MAX line.
3. A Stuck Brake Caliper
A stuck brake caliper that leaves the brake pad depressed partially or fully against the rotor can also cause severe friction and the smoke of overheated brakes. This could be caused by poor brake lubrication when the new brake pads were installed, excess brake fluid, a clogged brake line, or badly rusted brake calipers.
One of the most telltale symptoms of a stuck brake caliper is the car pulling hard to one side when you brake. It might also pull like you have an alignment problem when you set off again. You’ll likely hear metal grinding noises or squealing as the brake pad rapidly grinds down on the rotor.
How to Fix
A stuck brake caliper that’s causing one brake to smoke usually requires you to change both calipers on that axle. Even if you can get the caliper unstuck again by lubricating it, there’s a very good chance that rust, corrosion, or whatever caused it to stick in the first place will happen again.
If you’re a reasonably capable DIY mechanic, you might be able to replace both calipers for parts cost of around $150 to $250. Then, be prepared for the brake job to eat up most of your Saturday afternoon.
If you take the car to a mechanic, they can usually replace both calipers for an additional $150 to $250 of labor time added to the cost for a total of $300 to $500 for dual caliper replacement.
Just keep in mind that these costs don’t include other things like new brake pads or replacing the rotors, which you might need to do if you drove with a stuck caliper for too long.
4. A Partially Clogged Brake Hose
A clogged or partially clogged brake hose that prevents the brake fluid from returning to the brake lines and the master cylinder can cause the caliper to stay slightly depressed on one rotor. This closely replicates a stuck or seized caliper. Except in this case, the problem is in the brake hose itself.
If your car is pulling to one side and smoking on just that one wheel, but the caliper looks crisp and clean, then you might want to check the brake hose.
You can test if it is indeed a clog in the brake hose by first jacking the car up and putting it in neutral with the engine off. You should be able to turn the tire by hand relatively easily. Then, have someone else step down hard on the brake pedal 7 to 10 times to build up brake pressure. Wait 3 seconds, and then try to turn the tire by hand again.
If it’s suddenly very stiff, then you have a partially clogged brake hose that isn’t allowing the pressure of the brake fluid to move back toward the master cylinder efficiently.
How to Fix
If you’re a reasonably capable DIY mechanic, you might be able to replace your own brake hose. Though there’s a serious risk of accidentally drawing air into the master cylinder if you don’t bleed the brakes properly.
If you’re not comfortable with replacing your own brake hose, there’s no shame in bringing it to the shop.
A mechanic will charge you around $75 to $100 to replace a single brake hose. Though chances are good that all your brake hoses are old and could stand to be replaced soon. So, the wise move is to save a little money and have all of them replaced for around $175 to $300.
5. Dusty or Rusty Brake Pads
If your car’s been in storage for a few months, dust and/or rust can build up on the brake pads or rotors, causing them to smoke the first few times you step on the brake pedal. You might even hear a metallic rasping or grinding noise.
If the rust on the brake pads and rotors is minor, it should clear up in a dozen or so miles. If it’s more serious, you might need to clean the brakes.
How to Fix
Cleaning rust off your brake pads and rotors calls for a non-chlorinated brake cleaner, which won’t affect the friction relationship between the brake pads and the rotors. The bonus here is that brake cleaner is multi-purpose, and you can use it to clean other dirty parts and lawn equipment.
Berryman 2420 Non-Chlorinated Brake Parts Cleaner
CRC (05084-12PK) Brakleen Non-Chlorinated Brake Parts Cleaner
To clean rusty brakes, follow these steps:
6. A Bad Master Cylinder
While it’s somewhat rare, a bad master cylinder where the seals are stuck in place can cause all four calipers to depress onto the rotors, which causes enough friction for the brakes to smoke as they overheat. In a scenario like this, the problem will usually happen on all four wheels.
However, if you have a split, diagonal master cylinder with a single bad seal, it could cause one front brake to lock up on one side of the car. Then, the back break locks up on the other side of the car. The car will then pull just slightly toward the front brake, which bears more braking force.
How to Fix
With a bad master cylinder, the wisest course of action is to have it replaced rather than fiddle around with trying to figure out how to fix whatever’s gone wrong inside it. Since you’re dealing with hydraulics, it’s usually best to take it to a shop.
The cost to have a mechanic replace your master cylinder typically runs between $350 to $500. However, you might also need a bad replacement.
7. Stuck/Rusty Manual Parking Brake
Manual parking brakes with a cable system can often get rusty and stick, causing enough friction to make the brakes smoke as you drive down the road.
In a scenario like this, you park on a hill or steep incline and set the parking brake. The cable system tightens the parking brake on the rear wheels.
When you go to leave, you pop and release the parking brake, and everything seems fine inside the car.
Then you drive off, and you might hear a rasping, grinding, or even a strange howling noise coming from the back of the car, and the engine feels strangely sluggish. When you pull to a stop and check your side mirrors, you see smoke coming out of the back wheel wells.
How to Fix
If you’re lucky, you might be able to jostle the parking brake into releasing by shifting back and forth between drive and reverse, then setting and releasing the parking brake. If it finally does go, you’ll usually hear a “Clunk” noise.
If this works, you’ll still have to have the parking brakes fixed, as they’ll likely jam up again. In the meantime, if you need to park on an incline, simply turn the front tires so that if the car were to rock backward, the wheels would be stopped by the curb.
If you have some experience working with manual parking brakes, it might be possible to fix them, clean the rust, and relubricate them yourself. Though you still might want to bring it to a mechanic to handle the job and have them perform a complete brake inspection.
The cost to have a mechanic fix or replace rusted parking brakes usually runs between $225 to $300. Sometimes, they’ll give you a discount on the parking brake repairs if you’re also getting a brake job at the same time.
Expert Advice to Prevent Your Brakes from Smoking
There are several things you can do to help prevent brake smoking and overheating. This includes things like driving cautiously, as well as making a point to maintain your brake system properly.
1. Minimize Stop-and-Go Traffic
Stop-and-go traffic is one of the more common causes of brake overheating that leads to brake smoke.
If possible, try to find alternative routes that avoid the worst of the traffic. If it simply can’t be avoided, try to avoid aggressive driving habits. Stay within the speed limit and brake gently.
2. Maintain Your Brakes
Routine brake maintenance is another essential way to help prevent brake smoking. Well-maintained brakes with pads that aren’t overly worn are far less likely to overheat and start smoking. They’re also less likely to suffer warped rotors.
Having a routine brake inspection performed every time you rotate your tires will go a long way toward catching brake system problems before they lead to brake smoking. This includes making sure that your brake fluid levels are correct for the thickness of your brake pads to prevent brake drag.
3. Use Strategic Engine Braking
Engine braking can be done by downshifting and using a low-range gear when going down a steep, long grade. In a car with an automatic transmission, you can use the low gear (L) setting or the (2) to help the engine brake. So long as the car is staying under 30 miles per hour.
4. Don’t Ride the Brake Down Steep Hills
When going down a steep, short hill, it’s better to step on the brakes for 3 to 5 seconds to reduce speed rather than trying to ride the brake down the hill lightly. By only applying the brakes periodically, you give the pads and the rotors more time to cool, which reduces the heat from friction that can cause brake smoking.
Frequently Asked Questions
What Should I Do If My Brakes Are Smoking?
If your brakes are smoking, and it’s not just because the new brake pads haven’t been bedded in, then you need to pull the car over and park it. If it turns out to be a simple problem that you can fix on the roadside, you might be able to drive home or to the mechanic after the brakes have fully cooled down. Though most of the time, the wisest move is to have the car towed to a brake specialist mechanic.
Is It Safe to Drive with Smoking Brakes?
If the cause of your smoking brakes is something simple like a stuck manual parking brake or brake drag from overfilled brake fluid in the system, you might be able to remedy it on the hard shoulder. Otherwise, all the other things that can cause your brakes to smoke are serious road safety hazards.
Some states make it illegal to drive with a failing brake system not to mention the fact that overheated brakes do a very poor job of stopping the car.
End Brake Smoke for Good
Smoking brakes are most often caused by abusive braking habits or faults that cause one or more brake calipers to stick on the rotors. If you’ve recently used the parking brakes, and the smoke is just in the rear, then it could be that the rusted cables are causing the parking brake to stay partially stuck.
If you’ve recently had a brake job and didn’t bleed the brake lines or added extra brake fluid to the point your brake fluid reservoir is past the MAX line, then it might be a simple case of brake drag. Extracting some of the fluid might be an easy fix.
If you have smoke coming from a single wheel, and the car is pulling to one side when you brake, then you’re likely dealing with a stuck brake caliper.
This could be a fault in the caliper itself, such as rust on a caliper piston or a partial clog in a brake hose that prevents the hydraulic pressure from dissipating after you take your foot off the brake pedal.
You’ll likely need to replace both calipers on that axle and/or replace the brake hose.
Written By
Jason Farrell
Jason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.