What is the reason for the burning of gas valves in Ningdong 6320 diesel engines?

[NevaehMarie]

Ningdong 6320 diesel engines burn gas valves due to severe matching wear or faults such as valves not closing tightly. Engine Introduction: An engine is a machine capable of converting various forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (Stirling engines, steam engines, etc.), jet engines, electric motors, etc. Engine Working Principle: The working principles of two-stroke engines and four-stroke engines are different, with the majority of automobile engines being four-stroke. The working cycle of a four-stroke gasoline engine consists of 4 piston strokes: intake stroke, compression stroke, power stroke, and exhaust stroke.

[SanPatrick]

I've repaired quite a few Ningdong 6320 diesel engines, and valve burning issues are quite common, mainly caused by excessive engine temperature leading to valve metal fatigue. For example, prolonged high-load operation causes exhaust pipe temperatures to skyrocket, coupled with poor lubrication and insufficient oil supply, which increases valve friction and makes them prone to burning. Additionally, poor fuel quality with many impurities leads to carbon buildup, clogging the exhaust and worsening valve cooling, thereby exacerbating damage. Cooling system leaks or fan failures can also cause temperature to spiral out of control. I recall one case where a truck on a long-distance trip had completely melted valves after frequent starts and stops, and inspection revealed sulfur content in the diesel was excessive. For prevention, regular carbon cleaning and checking the lubricating oil are crucial, and don't let the engine run overheated for too long.

[LeCarson]

As an experienced driver, my Ningdong 6320 has had its valves burned out several times after prolonged use, mostly due to driving habits and maintenance neglect. For example, prolonged high RPMs while climbing mountain roads caused the engine to overheat, leading to a sudden rise in exhaust temperatures, which oxidized and peeled the valve surfaces. Using low-quality diesel is even worse—impurities cause rapid carbon buildup, clogging the exhaust and worsening the burning. When the lubrication system's oil ages, the valves lose protection, leading to excessive friction, and after tens of thousands of kilometers, the valves are completely ruined. Once, I forgot to adjust the valve clearance, leaving it too small, and the friction-generated heat during operation directly melted them. So, in daily use, avoid sustained high-speed driving with full loads, choose good-quality diesel, and change the oil regularly—this can significantly reduce risks and extend valve life.

[DelEden]

The causes of valve ablation are nothing more than high temperature and impurities. The exhaust valve position of the Ningdong 6320 diesel engine is prone to overheating, and poor fuel quality or corrosive components accelerate erosion, while insufficient lubrication exacerbates friction. Carbon deposits blocking the exhaust passage lead to uncontrolled temperature rise, causing the valve metal to deform and melt. Cooling system failures, such as water leakage, further worsen the situation, ultimately leading to valve burn-out and failure. Early inspection and maintenance can prevent most issues.