Why Does My Engine Smell Like Rotten Eggs?

If your car’s engine smells like rotten eggs, the catalytic converter is unable to convert the hydrogen sulfide that is found in your vehicle’s exhaust. You may also smell rotten eggs around the battery if it is leaking sulfuric acid. This is just one odor that your automobile will release if it is having a problem. Here are the other common odors and what causes them.

Hot Wires/Burning Rubber

You may smell hot wires and or burning rubber coming from the engine or elsewhere in your automobile if your vehicle’s electrical system is producing too much electricity. Ideally, you should never have more than 14.5 volts of electricity surging through the system. Anything higher than this will overheat the system and melt the wires and rubber insulation.

Sweet/Musty Syrup

Your automobile may release a sweet and musty odor that smells like pancake syrup if the engine has a coolant leak. Coolant can leak out of the radiator and radiator hoses. It can also leak out of the heater core or the cooling system seals and gaskets. The reason why the coolant smells sweet and musty is that it contains ethylene glycol. Please note not all coolants have this chemical.


Speaking of musty odors, you can also get musty odors coming out of the vents if there is mold or mildew in the ventilation system. One of the easiest ways to dry up the mold and mildew is to turn on the vent, set it to its highest setting, and let it run until you no longer smell the odors. It is particularly important to dry up mold and mildew if you live in a moist climate.

Hot Oil/Burning Engine

It can be damaging to drive your automobile if you smell hot motor oil or a burning engine. This is a sign that the oil level is too low and the parts are producing excess heat because they are not lubricated properly. The same thing can happen in the transmission if the transmission oil is too low. The transmission parts will rub against each other and overheat.

Burnt Paper/Carpet

Finally, although these two parts are not in the engine, it is worth discussing their associated odors if something is wrong. The odor of burnt paper means that your clutch facing is overheating. This can happen if you write the clutch. The odor of burning carpet means that your brake pads are too hot. This is a sign that your brake system is overheating.

We are here to help, so call us today to set up a service appointment for your automobile if it is producing strange odors.

Photo by Aigars Reinholds from Getty Images via Canva Pro

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