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Diagnose Types of Car Smells – What They Are and What to Do?

Do you detect an unusual smell while driving your car around? This could indicate serious problems ahead. Knowing how to recognize them quickly could save you a lot of money in the end.

What about taste, then? Ok, maybe not taste since most automotive fluids are toxic but you get the point!

So what are the different types of smell that can come out of your car and what can you do about it?

Gasoline smell

car smells like gas inside

The smell of gasoline is one of the most frequent smells to happen in a car and probably one of the most potentially dangerous. It’s well-known that gas, when submitted to heat, burns and a car engine is producing a lot of heat.

They simply don’t go well together.

Fuel Leak

The first thing to think of, when detecting a gas smell, is a leak in a fuel delivery mechanism, such as a fuel injection line or fuel tank.

Park the car safely onto the side of the road and inspect for gas leaks under your car. Placing a piece of cardboard under the car may help you easily find where it’s coming from.

If any of your gas lines, fuel tanks, or any component of the fuel system is leaking, you shouldn’t try to drive the car anymore. If the leakage is rather large, the fuel pressure could rupture the line and the fuel would stop being properly delivered to the injectors. The engine would starve pretty quickly and it would simply stop running, leaving you stranded somewhere on the road.

Bad combustion

If you can’t find a leak pouring under the car, the problem may simply be located elsewhere. An engine burning a richer than normal air/fuel mixture, for example, will eventually fill the catalytic converter with gas fumes. This leads to a gas smell coming out of the exhaust.

In fact, everything modifying the internal combustion of the engine and making it any less than perfect can make your car smell like gas. A dirty engine air filter, old spark plugs, a malfunctioning MAF and every faulty component from the intake, exhaust or ignition system can cause a car’s exhaust fumes to smell like gas.

Related: How To Choose The New Spark Plugs

Burning Oil Smell in Car

Oil Leaks

The smell of burned oil could mean that oil is leaking somewhere and it’s getting on the exhaust system or any other hot part of your vehicle. A quick inspection of the engine bay will let you know if your engine has an oil leak.

The most common cause of oil leaks is the oil filter, the drain plug or the oil pan seal, the valve cover gasket and the oil pressure switch. Cam or crank seals and brake fluid lines can also fail but it’s definitely not as frequent as a leaking oil pan.

Oil is too hot

If for whatever reason, your engine oil or transmission fluid runs hotter than what it’s supposed to, a burned oil smell can happen. Check your engine’s temperature gauge to make sure the engine isn’t overheating.

In the case of an automatic transmission, a failing transmission cooler can cause the transmission’s temperature to rise to an incorrect level, causing the oil to literally burn. Check the color of the fluid on the dipstick, if you are lucky enough and your car is actually equipped with one. Most newer cars don’t have dipsticks anymore and yes, it’s a bummer!

The transmission fluid should be a bright red and have a slightly sweet odor. Its main purpose is to lubricate all the moving parts of the transmission and to keep it cool to avoid premature wear of its various components.

Whenever the fluid becomes of a darkish brown color, becomes thicker and opaque, or if your transmission is leaking and the fluid level gets too low, the fluid will overheat and begin to burn, causing a burned oil smell.

In addition to having to deal with a car with a bad smell, burned transmission fluid will not be able to lubricate the various components and will sometimes cause the transmission to slip while changing gears or take longer to shift.

Burning Rubber Smell From Car

Slipping belt

drive belt is slipping

The smell of burned rubber could indicate that the drive belt is slipping on the pulleys. This situation usually comes with the typical loud “belt-slipping” screeching noise. To fix this problem you’ll have to identify if the belt is slipping because:

– The belt is loose, old, cracked, worn or dried out;

– One of the bearings on any of the pulley is worn out, causing the pulley to be harder than usual to turn;

– The tensioner is loose, broken or stuck;

– The threads on one of the pulleys are damaged.

The most common cause is obviously a loose belt. Drive belts need to be replaced at regular intervals, which is a lot shorter than the life expectancy of the water pump pulley for example.

Rubber parts

Rubberized parts, such as hoses and plastic undercovers, can also become loose and rub on moving parts. Plastic clips can also dry out with time and break. This causes wires and various rubber components to touch the exhaust and cause an annoying burned rubber smell.

Coolant Smell

coolant smell

The sweet smell of syrup can be a sign that the engine coolant is leaking somewhere. Look for pink or green fluid coming out under the engine. The coolant could also be blue if you own a Honda. Yellow or clear if it’s been replaced with a universal product. It could be pretty much any color in fact but it’s definitely not oily like engine oil would be. Auto mechanics in the past had been known to recognize coolant by tasting it because it tastes super sweet and oil doesn’t at all.

But that was before.

When mechanics still smoked while replacing fuel tanks. When squinting was as good as wearing protective goggles.

Before we actually knew that coolant is known to cause cancer. So don’t do that. Just smell it instead.

Checking the coolant level in the expansion tank is also a good idea. If it’s empty, it’s probably leaking. Fill up the tank to the FULL level. Then, take your car out for a drive and look at the level later.

Burned fabric smell

The smell of burning fabric could be a sign that your brakes are overheating which is a definite danger to safety. When brakes are heating up, the braking distance of your vehicle will quickly increase to a point where they won’t be braking at all!

brake overheat

Overheating brake, especially drum brakes, can also cause the brake fluid to boil and that’s not a good idea. Brake systems work based on one assumption: that fluid doesn’t compress. Every pound of pressure applied to the brake pedal directly transfer to the brake pads or lining.

But air, unlike a fluid, is easily compressible. When the system is filled with boiling air bubbles, the brake pedal will go straight to the floor when pressed and the brakes won’t slow down the vehicle. In such a case, you’ll have to pull the handbrake and hope for the best. Not cool.

The main cause for overheating brakes is stuck brake pads. When rust is building upon the brake pads and caliper pins, the brakes won’t return to their original position when the brake pedal is released and will stay in contact with the rotors at all times. Just as if you were still holding the brakes while stepping on the gas. The temperature will obviously rise quickly and the pressure transfer property of the brake fluid will lower proportionally.

Brake pads also wear out a lot faster as temperature rises. The material will become softer and, if the rotors are hot enough, they may literally disintegrate when braking.

Exhaust smell in the cabin

exhaust fumes

This one is pretty self-explanatory. A leaking exhaust system will blow exhaust fumes inside the cabin. Depending on where the exhaust is leaking, the situation can go from bad to really bad real quick.

If it’s leaking near the muffler or at a flange near the back of the car, the fumes will penetrate using the air vent in the bumper, small holes in the trunk, the fuel pump access door under the rear seats, etc.

Exhaust fumes contain carbon monoxide, sulfur dioxide, nitrogen oxides, and formaldehyde only to name a few. I don’t even have to mention how toxic these fumes are. Everybody knows that.

If you smell exhaust fumes in the car, stop it and get it towed to the nearest repair shop right away. If you can’t, turn all the windows down, stop the air conditioning to prevent blowing the fumes straight into the car at full blast, and keep your head out of the window if you need to, but don’t gamble with your life. Your car is not worth dying, remember that!

Rotten egg smell

A rotten egg smell is never pleasant, but if it emanates from your exhaust, it could mean a few dollar bills less in your pockets. In fact, if this is the case, your catalytic converter is probably not working right.

The catalytic converter is a component of the exhaust system that transforms the harmful emissions generated by the engine into non-hazardous compounds. Without a catalytic converter, hydrocarbons, carbon monoxide, and nitrogen oxide would be released into the air by the muffler and could harm your health.

Driving with a faulty catalytic converter on your car is not as deadly as inhaling fumes from a leaking exhaust pipe but it sure costs a lot more to fix. Cats are complicated pieces of equipment and the materials needed to make them are really expensive. There’s no real way around it or cheap fix for this one.

How To Get Rid of Bad Car Smells

Obviously, you’ll have to fix the problem first. It makes no sense to try to get rid of the smell if the problem is still present.

But, what if your car has already been fixed up and the smell is still there?

The first thing to do is to ventilate the car as much as possible.

Use an odor absorber

Put a container of odor absorber in the car, remove the lid and let it work. The smell should dissipate in a couple of days.

Use bicarbonate

Sprinkle the inside of the car with baking soda. Put some on the floor and on the seats. Let the product work overnight and vacuum in the morning.

Use an odor destroying deodorant

Smell-destroying deodorizers can destroy all the bad odors in a car pretty quickly. Spray some on fabric and mats, let it sit and repeat until the smell is gone.

Essential oil

Pour a few drops of pine or mint essential oil on a washcloth or cloth, roll it into a ball, and let the fragrance spread. Change it every day or so.


For non-fabric surfaces, wipe with a towel moistened with a mixture of 3/4 water and 1/4 white vinegar.

Vinegar works with most odors but I personally think it leaves a weird odor after but that’s only me. I suggest you use this technique with one of the deodorizing ones so it will effectively clean plastic surfaces but your car won’t smell like vinegar for weeks.

Resistant bad odor

The only way to remove stubborn odors is to thoroughly clean the inside of the car: carpet, mats, and seats.

To clean the trunk, generously moisten the inside of the chest with water and detergent, and vacuum up immediately after. Use a hairdryer or a hot air blower to dry up the trunk and sprinkle the fabric with baking soda.

Leave it overnight and vacuum in the morning.

Last words

Odors can tell you a lot about how great your car is running. Stay on the lookout for unusual smells and learn to differentiate them. Being able to pinpoint the correct cause every time takes a lot of practice. When in doubt, always get your car checked by a full-fledged mechanic and don’t be afraid to ask questions.

Make sure you understand what was the problem and what they did to fix it so you can troubleshoot it by yourself next time. Understanding how your car works and what are the symptoms of various car failures will not only save you money in the long run but it will also help you be more confident on your next trip to the auto repair shop.

Turning a bad experience into a learning experience will definitely help to reduce the pain of seeing your car on the operating table again.

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