Jetta's engine is very loud. What happened?

The lubrication performance of the engine decreases.

Engine oil is an important part of engine lubrication. Exceeding the optimal period of engine oil lubrication will affect the working condition of the engine. When the oil lubrication fails, it is easy to cause problems in engine operation, and the lubrication function becomes worse, resulting in friction and noise in engine operation.

Belt aging

The water pump belt or engine belt slips after aging, or the water pump impeller, water pump bearing or generator bearing are worn due to lack of lubrication, resulting in abnormal sound.

Valve leakage

Abnormal sound caused by valve air leakage is outside the valve chamber, which is generally more obvious at high load and low speed. Noise increases with the increase of load, mainly due to valve seat inclination or small valve clearance, resulting in valve ablation or lax valve seal and air leakage.

Low gasoline grade

Low-grade gasoline for automobiles with high compression ratio is not easy to burn completely, which leads to a rapid increase in carbon deposition. Low-grade gasoline has poor antiknock performance and is easy to knock. Under the repeated action of high temperature and oxygen, colloid and carbon deposit are easy to form hot particles, which are adsorbed on the surface of combustion chamber, promoting surface ignition and increasing combustion noise.

Poor fuel quality

When inferior fuel is used, the combustion situation in the engine will become worse, which will cause the engine to vibrate violently and produce noise.

Aging of gripper pads

The claw pad plays the role of supporting the engine. When it ages, it can't work normally. At this time, it can't be repaired, only a new claw pad can be replaced.

Maintenance is not timely.

Engine acceleration is weak and throttle power is insufficient, which is usually caused by untimely maintenance. Need to check whether the air filter, spark plug, ignition coil, gasoline filter and oil pump need to be replaced or blocked.