What Causes Abnormal Noise During Engine Idling?

[ZacharyDella]

Engine idle abnormal noise may be caused by the following reasons: Timing chain elongation, tensioner pressure loss, balance shaft wear: Timing chain elongation is generally caused by metal fatigue. After prolonged driving combined with the high-temperature working environment of the timing chain, elongation can easily occur, leading to abnormal noise. The tensioner is connected to the oil passage and adjusts the tightness of the timing chain through oil pressure. If the tensioner oil passage is blocked or the internal check valve loses pressure, the chain may loosen and produce noise. The balance shaft is used to reduce vibrations generated during engine operation. If the balance shaft oil passage is blocked, it can increase wear on the journal and bearings, resulting in noise. Camshaft, crankshaft, and connecting rod bearing wear: If the vehicle uses low-quality oil, excessive sludge may form in the engine, blocking the lubrication oil passages and preventing oil from reaching components that require lubrication and cooling. This can cause wear on the camshaft, crankshaft, and connecting rod bearings, leading to noise. Additionally, if the engine lacks coolant, causing excessive engine temperature, the above phenomena may also occur. In severe cases, it can even lead to cylinder scuffing or bearing seizure. Increased timing variable wheel clearance: Variable valve timing can adjust according to engine speed and operating conditions, typically using hydraulic control to advance or delay the camshaft timing gear's internal rotor by a certain angle. If the variable timing wheel's internal rotor is stuck or the oil cavity is worn, the clearance may increase, causing noise. Excessive valve clearance or damaged rocker arm: The rocker arm is a lever mechanism that presses the valve, and the valve clearance is mainly controlled by the hydraulic lifter. Damage to either can result in valve noise.