Identifying Bad Smells on a Car

Does your car smell like rubber burning or rotten eggs?

A car that is running fine should not emit strange smells. If you smell something unpleasant, don't ignore that strange smell. This guide will help you identify car problems based on the smell. 

One way to diagnose car problems is by identifying that strange smell. Often the first sign that something is wrong with your car is a bad smell. It is important to identify those odors before they become serious car problems.

Let take a look at some of the most common car smells and possible causes. 

Rotten eggs smell

rotten egg smell in car

A vehicle emitting a rotten egg smell is a sign of a bad or plugged catalytic converter. The catalytic converter is responsible for converting harmful gases into friendly gases that are emitted into the air.

When the catalytic converter is working inefficiently, the hydrogen sulfide, which is present in gasoline, is usually converted to sulfide dioxide, which is odorless. Replacing the catalytic converter costs $250-$400 for an aftermarket universal cat, or $700-$1500 if you decide to install an original catalytic converter at the dealer. 

In addition, a faulty fuel pressure regulator can also contribute to a rotten egg smell.  

Fuel / Gas 

car smells like gas

A car smelling like gas is extremely dangerous. That means there is a possible fuel leak somewhere in the fuel system. The fuel system is enclosed, and neither fuel nor fuel vapor is allowed to escape. However, if this fuel smells is present. I suggest checking the fuel system as soon as possible. 

Check the following:
•    Fuel line going from the fuel pump to the engine
•    Check fuel injector seals for possible leaks
•    Check all fuel vapor related to emission
•    Check all fuel line and hoses at the fuel tank
•    Check fuel tank for possible damage and leakage
•    Check fuel pressure regulator hose

Burning Oil Smell

car smells like burning oil

There is a difference between a car smelling like oil and a car burning oil. In this discussion, we will discuss car smells like burning oil. A car smelling like burning oil is a sign that there is external engine oil leaking.

Here are the possible areas that should be checked for leaks. 

•    Bad valve cover gasket can leak on to the engine and exhaust 
•    Bad oil pan gasket can leak on to the exhaust system
•    Bad camshaft and crankshaft seal
•    Leaky rear main seal

Vinegar Smell in the Cabin

car smells like vinegar

If a car smells like vinegar, it is a sign that there is mold in the air duct. This is due to condensed water left behind when the air conditioner has been used. Moreover, the dirty cabin air filter can also contribute to a vinegar-like smell. To reduce condensed water from building up, turn off the air condition five minutes prior to turning the vehicle off. Also, replacing the cabin air filter may help along with disinfectant spray. 

Excessive Smoke Smell

car smells liek smoke

A car that smells like smoke is a sign of a leaky exhaust system or possibly a severely worn engine.

Check the following:

•    Leaky exhaust manifold gasket
•    Worn piston rings and low compression (use compression gauge)
•    Leaky exhaust fumes somewhere in the exhaust downpipe
•    Rusted muffler
•    Leaks between the catalytic and resonator 

Something is Burning

car smells like burned plastic

A car is made up of many components. One of the components commonly used is plastic. Plastic can be used anywhere from the interior of the vehicle to the exterior of the vehicle.

If your vehicle smells like it is burning, here is what you should check.

•    Check between the wheel well and tires. The wheel well can rub against the tires.
•    Check for loose engine undercover that may be touching the exhaust system
•    Check the exhaust system for possible melted plastic  shopping bag that may have got caught on the exhaust 
•    Check for engine cover that may come loose and burning on the engine 
•    Check for possible loose engine plastic components on the engine bay area that may come loose
•    Check for possible tools  on the engine bay that may have accidentally been left behind by mechanic or technicians

The smell after an oil change

car smells after oil change burning

There are a few possible reasons why a car may smell after an oil change. During an engine oil change, the mechanic or lube tech needs to drain the oil and remove the oil filter. In this process, the engine oil can flow from the oil filter housing or drain plug to different areas of the vehicle, usually to the lowest point, sometimes flowing to the exhaust system. The residue/oil is then gets burned off by the exhaust. 

The wired smell from air vents

smell from air vents

The air vents can emit a few strange odors.

Here are some of the odors can be emitted:
•    Foul smell: a foul smell can be a sign of a dirty cabin air filter that has not been replaced
•    Mold smell: a mold smell is water residue left behind after the air condition has been run for a while
•    Dirt smell: It is possible that if you drive on the unpaved road; dirt and can enter the air vents, therefore, emitting a dirt smell 

Bad Clutch Smell

bad smell from clutch manual transmission

The smell from a clutch system is a sign that the clutch is wearing out. Usually, it smells somewhat like burned metal rubbing against each other. If the vehicle smells like a burned clutch, it is time to replace the clutch.

Here are some of the following symptoms that may display that:

•    Unable or difficulty shifting gears
•    RPM jumps when shifting gears
•    Burning metal smell
•    Grinding noise when shifting

The car smells like antifreeze outside.

semll of leaking coolant

One of the most common coolant smells is from a leaky heater core, cracked radiator, or damaged coolant hose. The upper radiator hose, thermostat housing, lower radiator hose, heater core hoses, broken radiator, broken coolant reservoir can all contribute to coolant smell when these components start to leak. 

By  YOUCANIC Automotive Experts

Published on: Tuesday, December 10, 2019.
Updated on: Thursday, December 31, 2020