Is Putting a Magnet on the Exhaust Pipe Actually Useful?
2 Answers
Putting a magnet on the exhaust pipe is useful. Below is a detailed analysis of the specific reasons for abnormal noises coming from the chassis after parking: Cooling noise from the catalytic converter: The normal operating temperature of a catalytic converter is between 400-800°C. After the engine is turned off, its operation gradually stops, and the temperature begins to drop, causing the internal metal components to expand and contract due to heat, resulting in abnormal noises. Cooling noise from the exhaust pipe: Typically, the exhaust pipe reaches temperatures of over 200°C during cold idle. When the vehicle is under high load or when there is combustion of the air-fuel mixture in the exhaust pipe, the temperature can rise even higher. As a result, the exhaust pipe also expands and contracts due to heat, producing abnormal noises, which often originate from the front end of the exhaust pipe or the flexible joint area. Turbo cooling noise: Under normal conditions, exhaust gases can reach temperatures of up to 700°C, accelerating the friction-induced heat from the turbo's rapid rotation. After the engine is turned off, the heat-induced expansion and contraction become quite noticeable, leading to abnormal noises.
As a veteran driver with decades of experience, I once tried the method of attaching magnets to the exhaust pipe to catch metal shavings. For the first three months, I checked daily for changes, only to find some dusty particles collected. Later, an apprentice at the auto repair shop told me that 90% of the metal wear debris from the engine is actually trapped by the oil filter. The exhaust pipe mostly contains carbon deposits and combustion residues, with very few metal shavings. Moreover, magnets tend to lose their magnetism due to the high temperatures in the exhaust pipe. After one long trip, even the magnet's casing got deformed from the heat. Now, I've switched to full synthetic oil paired with long-life oil filters, which proves to be a much more reliable solution.
