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Name: Hayward
Status: student
Grade: 9-12
Location: LA
Country: USA
Date: Spring 2013

I had a get-together the other day and I was hooking up a stereo system in the building and I laid a speaker on the hood of my truck and a friend came up to me and said not to keep it there to long because it could affect the carburetor and motor. Can magnets affect a carburetor and/or motor?

Hi Hayward,

The short answer is " absolutely not"! A magnet laid on the hood of the car will have absolutely no effect whatsoever on a car's carburetor or any part of its engine. Your friend is out to lunch on this one!!!

Regards, Bob Wilson


Magnets in a speaker are not big enough (by a long shot) to effect a carburetor or engine. Magnets built big enough could eventually build eddy currents in the engine block to disrupt the spark plug firings and cause the engine to stop, but those magnets would have to be at least as big as a house.

Some people have claimed that sparks in the focal point of a high gain antenna can shut down an engine, but when you start asking for details they start backing off on their claim. The signal is called an ?ultra wide band signal? because the frequency of such a signal runs from 100 KHz to 1 GHz. You can Google ?wide band signaling? to find out more, like this article:

Sincere regards, Mike Stewart

Hi Hayward,

Thanks for the question. I am not aware of magnets (of the size of a speaker) causing any significant change to a motor or carburetor. In fact, some small engines do contain magnets--they are part of the magneto spark system. Speakers do contain magnets. Apart from the magnet attracting some of the iron parts in the carburetor or motor, I do not think any damage will occur. Frankly, if a part is able to be dislocated by a magnet, that same part would fall off during normal driving of the car.

I hope this helps. Please let me know if you have more questions. Thanks Jeff Grell

No. It is true that you would not want your carburetor valves to become magnetized, because they might stick, but a speaker will not magnetize your carburetor from that distance.

Tim Mooney


Unlikely. The metal hood will tend to shield any possible effect a magnet might have. Further, unless the speaker is close to some internal electronics controlling the car, it is unlikely that you would see any effect. Mostly, the engine compartment can be a harsh environment for electronics, and manufacturers design with this in mind, so the electronics is pretty well protected. As for any effect on the mixing or flow of gasoline, magnets will not have an effect unless you, for example, drop a magnet into the throat of the carburetor and physically block air flow. If anything, I would worry more about your speakers. They could be damaged by excessive heat if you are running the car with them sitting on the hood for too long. Many magical effects are attributed to magnets--purifying water, creating energy out of nothing, etc.--and you should eye all of them with a good measure of skepticism.

Kyle Bunch, PhD, PE

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