When you're driving your car and you notice smoking coming from the car, it is best to stop as soon as possible and find the source. The brake system is commonly to blame for the presence of smoke, which typically has a foul odor. There are numerous reasons the brake may be smoking, so here are a few tips to help you diagnose your problem.
Do you have new rotors?
When you first install new rotors, there may be a bit of smoke as you break in the new parts. There could be contaminants on the surface of the rotors that create smoke as the calipers make contact with the rotors. This should go away after you use the brakes for a short period of time. You can also use brake cleaner to get rid of anything on the rotors that might be causing the issue.
Did you check the calipers?
If cleaning the rotors did not work or you're not dealing with new brake discs, the calipers could be the source of the smoke. Stuck calipers drag along the rotors even when the brakes are not in use, and this additional friction leads to smoke. Calipers are designed to clamp the rotors and the brake pads together to bring the car to a stop, but they can get stuck and lock the brake pad against the rotor. You can visually inspect the calipers and test their movement by hand by attempting to move them back and forth.
How about the wheel cylinder?
Wheel cylinders on drum brakes can also get stuck and create smoke. Drum brakes used to be on every tire, but these days they are reserved exclusively for the rear tires in certain cars and others may not use them at all. In this setup, the wheel cylinder may become stuck due to debris or corrosion. Just as in a sticky caliper situation, a stuck wheel cylinder puts pressure on the brake shoe. This increases friction on the brakes when the car is in motion, resulting in smoke and a noticeable stench.
Are your brakes clean?
A less common issue is simply that dirt and debris may have worked themselves up into your brake system. In this case, smoke would form as a direct result of this external material being caught in the braking mechanism. This can be solved by removing the foreign material from the brakes.