What are the causes of abnormal noise in the UY125 engine?
2 Answers
The causes of abnormal engine noise include premature fuel injection, diesel leakage from the injector, piston impact on the cylinder wall, excessive piston ring side clearance, impact between the valve stem head and rocker arm, and engine misfiring, among others. The specific cause needs to be determined based on different noise conditions, as detailed below: Abnormal noise caused by rough engine operation, commonly known as "knocking sound." The phenomenon is characterized by strong noise at low speeds, which can be clearly heard from a distance of several meters away, accompanied by difficulty in starting. After the engine starts, it runs unevenly, and coolant consumption is rapid. This noise is caused by premature fuel injection and requires readjustment of the fuel injection timing. Engine noise has a certain pattern, sometimes knocking and sometimes backfiring, accompanied by unstable engine speed and intermittent black smoke emissions. This irregular noise is caused by diesel leakage from the injector. When this occurs, the injector should be serviced. The engine emits a "clunking" or "thumping" sound, which is particularly noticeable at low speeds or during sudden speed changes, accompanied by oil burning. This noise is caused by excessive clearance between the piston and cylinder wall, increasing piston impact on the cylinder wall during diesel engine operation. The solution is to replace the cylinder liner or piston. A "clinking" sound, like a small hammer lightly tapping an anvil, can be heard along the entire length of the cylinder block, becoming more pronounced during sudden speed changes. This is caused by excessive piston ring side clearance and requires replacing the piston rings, and sometimes the piston as well. A "clicking" or "tapping" sound around the cylinder head cover is quieter when the engine is warm and louder when cold, persisting even when fuel supply is stopped at low speeds. The main cause is excessive valve clearance, leading to impact between the valve stem head and rocker arm, which requires valve clearance adjustment. Exhaust gas flow from the car shows obvious intermittency, with significant exhaust pipe vibration, and clear engine noise can be heard. This is caused by engine misfiring.
When riding my UY125, I've encountered engine noises. The most common issue is a loose or worn chain, which produces a rattling sound, especially during acceleration. Insufficient chain tension or an overly long chain can cause slippage and noise. Another reason could be insufficient or poor-quality engine oil, leading to increased internal friction, such as between the piston rings and cylinder, resulting in a clattering sound. Aging spark plugs are also a frequent cause, leading to delayed ignition and popping sounds, and in severe cases, engine shaking. Preventive measures include regularly checking chain tension, not skimping on oil changes, and preferably using the manufacturer-recommended oil type. Replacing spark plugs every few thousand kilometers can prevent most of these issues.
