11 Causes of a Burning Smell in Your Car
Internal combustion engines work on the principle of burning things to go faster. Ironically, you probably won’t notice a burning smell while driving down the road.
If you notice a burning smell in or around your car, it’s important to identify the cause and solve the problem. Some flammable materials can be very dangerous and can even cause a fire.
We’ve done our best to put these different smells into words, but smells can be very subjective and difficult to describe. If you’re still not sure what’s causing the burning smell, ask a trusted local mechanic for advice.
Causes of the Burning Smell
1) Brakes
Brakes slow your vehicle by converting the vehicle’s kinetic energy into heat energy. Of course, excessive heat can make your brakes smell like they’re burning.
When your brakes are burning, they smell like burnt carpet. It’s an organic yet metallic smell that gets stronger the closer your nose is to the wheels. Therefore, it is important to find out what is causing your brakes to get very hot.
Brakes work well Even if your brakes are working perfectly, braking hard can start to cause chaos in the car. Examples of strain on your brakes include driving downhill, repeated sudden stops, and even one emergency stop from a high speed.
If you notice a brake smell after heavy use, make sure to let your brakes cool before driving long distances, especially if you will need to brake hard in the near future.
Not letting your brakes cool can warp rotors or cause brake fade. Brake fade is the loss of braking ability due to exposure of brake components to heat. In extreme cases, brake fade can cause a complete loss of braking performance.
If you notice brake fade, you should change your brake fluid. When brake fluid boils, air gets into the lines and the existing brake fluid can’t withstand the heat as well as it used to.
Worn Brakes As brake components wear out, they become less heat resistant. Brake fluid is hygroscopic and will absorb moisture over time. This lowers its boiling point. For this reason, there is a minimum window thickness for every vehicle. If the rotor is too thin, it runs a high risk of excessive lateral runout, commonly referred to as rotor warping.
Stuck Brake Caliper
A stuck caliper means that the caliper is unable to release its clamping force on the brake pads of a particular wheel. This keeps the pads partially or fully connected to the rotor, exerting a constant braking force on the wheel as you drive down the road.
Faulty brake hose
When a brake hose is pinched, pressure enters the caliper but cannot escape. This forces the brake pads against the brake disc, causing symptoms similar to those of a stuck brake caliper.
Applying the brakes
During brake break-in, the brakes are intentionally heated to transfer a thin layer of pad material from the new brake pads to the brake rotor. This coating is a necessary component of the inherent frictional force. There are actually two types of friction that occur between the brake pads and rotors to slow your vehicle down: abrasive friction and adhesive friction.
Abrasive friction is what most people think of when they think of “friction.” Abrasive friction is the breakdown of the molecular bonds between the pad material and the brake rotor. This causes the two surfaces, the brake rotor and the pad, to essentially wear down as they rub against each other, resulting in wear.
Adhesive friction is the “sticking” between the pad material and itself, which requires a thin layer of brake pad material to be placed around the surface of the rotor. When the brake pads rub against the rotors, they stick to this thin layer as the rotor passes over the pads, then break the bond as they move away.
If you’ve just replaced your brakes and are breaking them in for the first time (and you should always break them in with a new set of pads), your brakes will almost certainly smell during the break-in process. This is normal and expected.
Your brakes will get quite hot when broken in properly, so be sure to let them cool before applying the handbrake to prevent the rear pads from sticking to the rotors.
2) Clutch (Manual Transmission)
Nobody likes the smell of a burnt clutch. Because the clutch is hard to access, the smell of a burnt clutch can also be the smell of burning money.
A burning clutch smells like burnt rubber. It’s a bit like burning brakes, but more organic and less metallic. Think burnt rubber and burnt popcorn. This smell is most often felt inside the car, but sometimes outside too. Excessive clutch slippage can also cause smoke to come from the engine compartment.
If your clutch is slipping excessively, you are most likely experiencing clutch odors. You may be intentionally slipping the clutch when you partially depress the clutch pedal.
3) Electrical system burned out
Modern vehicles have many computers and require a maze of electrical cables to connect to fuses, sensors, and other computers.
Blown fuse
Fuses protect electrical systems from excessive current. If the current draw is higher than the fuse is rated for, the fuse will blow. This prevents electrical current from flowing and protects your electrical components.
If the fuse keeps blowing, there’s a problem with the electrical system along its path. Make a wiring diagram and see which components are connected to this fuse.
Then grab a multimeter and test the various parts of the electrical system that share the blown fuse to make sure they’re within factory specifications.
Electrical Short
An electrical short means that the current path completes a circuit in a different way than the circuit was designed for. A fuse may blow because too much current may flow through the system.
An exposed wire may cause a short circuit when current flows between two wires with poor insulation. If there is no fuse to prevent a short circuit, a short circuit may also cause the cable to heat up enough to melt the insulation.
Melted insulation
The wires in a vehicle’s electrical system are encased in a wiring harness to protect them from the hot engine compartment and ambient conditions.
If any part of the wiring harness comes into contact with a hot part of the engine (such as the exhaust manifold), the insulation may melt. Melted insulation smells like burning plastic and can also cause shorts.
Arcing
Arc flash is accompanied by a distinctive electrical smell caused by the production of ozone gas. This smell can be described as smelling like burning chlorine.
If a high-voltage component is not properly insulated and is close enough to jump to a nearby conductive surface such as metal, an arc flash can occur. Spark plugs, ignition coils, and spark plug wires are three components designed for high voltage. Beware of arcing flashes. These are powerful enough to give a severe electric shock and can easily cause an engine fire if they ignite flammable materials such as fuel.
4) Air Conditioning System
The HVAC system is connected to the vehicle’s cooling system through the heater core, and if you have air conditioning, it’s also connected. A burning smell coming from the HVAC system could be an indication of a problem with one of the other systems. Musty Smell on Startup
It’s not necessarily a burning smell, but it’s common for your HVAC system to have a bit of a musty smell when you first turn on the blower motor. Sometimes, your HVAC system needs to clear out a bit of dust and other particles before you can drive off odor-free. This is especially true the first time you turn on your car’s heater.
Faulty Heater Core
The heater core is a small radiator that uses hot coolant from the engine to heat your vehicle’s interior.
If your heater core leaks coolant, it can cause foggy windows, overheating of the engine, and a burning rubber smell. Dirty cabin air filter
Most modern cars are equipped with cabin air filters, but these filters are often forgotten and ignored. A dirty cabin air filter can produce all kinds of odors, none of which are unpleasant. Replacing a dirty cabin air filter is a cheap and easy way to freshen up your car’s interior.
Faulty Blower Motor
A faulty blower motor or blower motor resistor can cause too much voltage or too little resistance, resulting in the fan spinning faster than intended and a burning smell. A melted case can smell like burnt plastic or an electrical smell. Overheating Air Conditioning CompressorWhen the coolant level is too low, your air conditioning compressor has to work harder to pump the remaining coolant through the system. If the system overheats, you may notice a burning smell.
5) Foreign Objects
Maybe your car is perfectly fine, but you picked up a plastic bag floating on the road and it ended up stuck in your exhaust pipe.
If you smell something burning and can’t smell it, it’s a good idea to do a quick check on your car to see if anything has dripped or gotten stuck in any hot parts of your car. The exhaust system has some of the hottest components in your vehicle, so that’s a good place to start.
6) Engine Oil Leaks
Oil dripping on the sidewalk is a nuisance that can litter your driveway. Dripping oil down the exhaust pipe is a serious problem that can cause an engine fire. When oil burns, it’s easy to tell because it will smell like burnt oil written on the dipstick.
Motor oil has a relatively high flash point compared to gasoline, but it can still burn under the right conditions. If your car smells like burning oil, have it inspected to make sure the oil isn’t a fire hazard.
Remember: If oil leaks from your vehicle, it won’t lubricate your engine. If you notice oil leaking or burning, check your engine oil levels more frequently. If your engine runs out of oil, it can cause fatal damage to your engine.
Recent Oil Change
If you or a technician changed your oil recently, the oil filler cap may be leaking oil into the warmer parts of your engine. If the leak is very small, it may eventually burn off on its own without causing any problems. However, if you have a larger leak, it will need to be cleaned out.
Oil can leak from a variety of places, but here are some of the most common places:
1. Valve cover gasket
2. Oil pan gasket
3. Drain plug
4. Oil filter housing
5. Camshaft seal
6. Front and rear crankshaft seals (main seals)
7) Melted drive belt
A melted drive belt (also called a serpentine or secondary belt) will smell like burning rubber and is often accompanied by a high-pitched squealing noise. High engine part temperatures or stuck pulleys can cause the drive belt to melt.
Stick accessory pulleys can cause a lot of friction on the drive belt, causing the belt to heat up. This belt slippage can cause a loud squeal. If you notice belt squealing, check that accessory belt tension is properly adjusted and that all accessory pulleys rotate smoothly.
8) Loose hoses
Fuel and vacuum hoses can melt if they come into contact with hot engine parts. You may smell burning rubber or plastic. On older vehicles, these clips can become lost or broken. For a quick alternative, cable ties work great for securing hoses.
Once you have tightened the cable tie, cut off any excess length. Do not place cable ties near the exhaust or where they may come into contact with other hot components.
9) Clogged catalytic converter
The catalytic converter converts toxic gases that cause the rotten egg smell into more harmful exhaust gases. The operating temperature of the catalytic converter can exceed 800 degrees Fahrenheit (427 degrees Celsius). A clogged catalytic converter can cause the exhaust system to get very hot, which can lead to a fire. A clogged catalytic converter can cause other symptoms, such as: B. Reduced engine performance. It often glows when it gets too hot.
10) Misfire or partial combustion
Partial or incomplete combustion usually has a gas-like smell, and the source of the smell is often the exhaust pipe. However, you may also smell gas coming from the cabin. Incomplete combustion can have a variety of causes and often causes the check engine light to come on in new vehicles. It may also cause sluggish acceleration.
Poorly calibrated engine
If the engine timing is wrong, the vehicle may be running with a suboptimal air-fuel ratio. A rich air-fuel ratio will cause a gasoline smell.
Fuel leaks
A fuel leak can cause the car to run lean and turn on the lean engine speed light. This is because the fuel leaks before it can reach the combustion chamber. If the fuel leaks, it can easily ignite and cause a fire, which is very dangerous.
11) Transmission oil leak
Transmission fluid lubricates the transmission and differentials. When it’s fresh and when it’s burned, it has a distinctly different smell from motor oil. When gear oil burns, it smells pungent, like a burnt clutch, but a lot like burnt bacon. Some exhaust systems are mounted very close to the transmission or transaxle, and if transmission fluid leaks and drips into the exhaust pipe, it can fill the interior of your car with a foul odor every time you stop.
Locating the Source of the Burning Smell
There are a few steps you can take yourself to find burning material.
1) Check the exterior
If you’re driving and smell something burning, stop as soon as it’s safe to do so. Then get out of the car and walk around it for a bit. Look for anything obvious, like a fire.
2) Check the engine
If you see smoke under the hood, don’t try to open it. Opening the hood will add more oxygen to the fire, creating a dangerous situation.
Open the hood if you think it is safe to do so. Look for any melted, smoking, or smoldering material. The smell should be stronger near the melted ingredients.
3) Perform a sniff test
As you move around the car, identify the area where the burning smell is strongest. To isolate the problem, start the engine and smell the air around you. Then go behind the car and smell it. Which side is the strongest? Continue splitting each part of the car in half until you reach the area with the strongest smell.
Can you drive while smelling a burning smell? Look for any obvious defects around the smell. If the smell of burning is strong and you are unsure if the vehicle is safe to drive in its current condition, have the vehicle towed to a repair shop to have the problem diagnosed.
If the smell is mild, you may be able to drive the car safely to the repair shop under your own power. Only do this if you don’t mind taking the risk. Otherwise, the vehicle is running smoothly and there is no visible smoke. If the smell gets bad or you see smoke, stop immediately.
