What Causes the Abnormal Noise in Baojun 730 Engine?

[QuinnAnn]

The causes of abnormal engine noise include premature fuel injection, diesel leakage from the injector, piston hitting the cylinder wall, excessive piston ring side clearance, impact between the valve stem head and rocker arm, and engine misfire, 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 sound at low-speed operation, which can be clearly heard from a distance of more than ten meters, accompanied by difficulty in starting. After the engine ignites, the operation is unstable, and the cooling water consumption is relatively fast. This abnormal noise is caused by premature fuel injection and requires readjustment of the fuel injection timing. Engine noise has a certain pattern, sometimes knocking, sometimes backfiring, accompanied by unstable engine speed and intermittent black smoke emissions. This uneven noise is caused by diesel leakage from the injector. When this phenomenon occurs, the injector should be serviced. The engine emits a "clunking" or "thumping" knocking sound, which is particularly noticeable during low-speed operation or sudden changes in engine speed, accompanied by burning engine oil. This noise is caused by excessive clearance between the piston and cylinder wall, increasing the piston's impact on the cylinder wall during diesel engine operation. The solution is to replace the cylinder liner or piston. A "clanging" sound similar to a small hammer lightly tapping an anvil can be heard throughout the cylinder block, becoming more noticeable with sudden changes in engine speed. This is caused by excessive piston ring side clearance. The piston rings should be replaced, and if necessary, the piston should also be replaced. A "clicking" or "tapping" sound is heard around the cylinder head cover, quieter when the engine is hot and louder when cold, and does not disappear when the fuel supply is stopped at low speed. The main reason is excessive valve clearance, causing the valve stem head to impact the rocker arm. The valve clearance should be adjusted. The exhaust gas flow from the car shows obvious intermittency, accompanied by severe shaking of the exhaust pipe and clearly audible engine noise. This is caused by engine misfire.

[Stewart]

I'm an ordinary car enthusiast who enjoys tinkering with vehicles. When driving my Baojun 730, I also encountered engine noise issues. There are usually many possible causes, such as aging or loose engine belts that squeak when you accelerate; it could also be worn-out water pump bearings making annoying rattling sounds at idle. More seriously, internal components might be loose, like excessive piston or connecting rod clearance, which produces a knocking noise at high speeds. I once dealt with a case where the owner ignored the issue, leading to burned-out bearings and requiring a costly full engine overhaul. So don’t take it lightly—if you hear unusual noises, it’s best to stop and check if the oil level is sufficient (low oil worsens wear). Regular maintenance like replacing belts and oil can prevent many problems. If you’re unsure about the noise source, visit a reliable repair shop—they’ll use professional stethoscopes to diagnose and fix the issue.

[DelJulianna]

With a background in auto repair, let's discuss the common causes of engine abnormal noise in the Baojun 730: Loose belts or timing chains producing sharp squeals or clicking sounds during acceleration; improper valve clearance adjustment leading to knocking noises; damaged water pump bearings causing continuous "humming" during operation; insufficient or incorrect viscosity of lubricating oil increasing internal friction sounds. During diagnosis, pay attention to the engine RPM when the noise occurs – high RPM may indicate timing issues, while low RPM could be related to the water pump. Use simple tools to check for belt cracks or slippage to prevent engine damage. It's recommended to inspect belt tension and oil levels every six months. If unusual noises are detected, avoid long-distance driving and seek immediate repairs to minimize chain-reaction risks.