What Causes the Abnormal Noise at 1800 RPM Engine Speed?
3 Answers
Abnormal noise occurring between 1800 to 2000 RPM is typically caused by low engine oil viscosity. Other possible causes include severe long-term wear of hydraulic lifters, aging of engine peripheral components, or excessive valve clearance. For noises at 2000 RPM, it's advisable to first check the valve clearance. Vibration Principle: When the engine is running, it generates vibrations at certain frequencies, with each RPM range producing a distinct frequency. If any floating object in the vehicle has a natural frequency matching or close to the engine's frequency, that object will resonate, resulting in particularly severe vibrations. Vibration System: An automobile constitutes a complex vibration system where nearly every component can potentially generate vibration noise. To prevent vibrations, there are essentially two approaches: securing the component firmly or altering its natural frequency. Some vehicles feature plastic counterweights installed on floating exhaust pipes specifically to prevent resonance in the exhaust system. It's also recommended to check whether any wiring in the instrument panel is loosely bundled or if wire connectors are touching brackets.
Engine noise at 1800 RPM is usually caused by resonance due to wear of internal components. With years of driving experience, the most common culprits are excessive piston ring or connecting rod bearing clearance, which creates rattling or clanking sounds from increased friction at medium speeds. It could also be related to the timing chain—if it's loose or the guides are worn, vibrations intensify at specific frequencies. Worn engine mounts are another factor, allowing greater engine displacement and making noise more prominent around 1800 RPM. Poor resonance point design might stem from loose chassis bolts or cracks in the exhaust system. Back when I replaced an old car, a similar noise was caused by oil pan seal failure leading to unstable oil pump operation. Don’t ignore it—get it checked at a repair shop promptly to avoid escalating into major failures like crankshaft damage, which increases repair costs. If the engine is quiet at idle but noisy when accelerating to this RPM, a comprehensive diagnosis is needed.
When the engine reaches 1800 RPM, there's an abnormal noise. I've experienced this issue myself—it might be a problem with the belt system. If the power steering or alternator belt has cracks, the friction noise becomes noticeably louder at that RPM. Alternatively, the exhaust pipe hanger might be loose, and the vibration point happens to match the engine frequency at 1800 RPM. My old car used to make this noise before, and the mechanic said it was caused by a hissing sound from a leaking turbocharger connection point, but you should first confirm whether your car has a turbo. The inspection method is simple: park the car, shift to neutral, and slowly increase the RPM to listen for the source of the noise. If the steering wheel vibrates, the engine mount might be damaged. I recommend regularly replacing belts and performing maintenance to reduce such minor issues and drive with peace of mind.
