Basic Knowledge About Engine

1. Why should diesel engines not be operated under prolonged overload or low load?

A: Every diesel engine has a power limit. Prolonged overload operation is extremely dangerous. If the load on the diesel engine increases to the point that the fuel injected into the cylinder does not receive sufficient air and cannot burn completely, it will emit thick black smoke. This overload operation not only increases the load on the engine components but can also cause cylinder scoring due to overheating and damage to the cylinder's lubrication.

According to regulations, diesel engines are only allowed to operate at 10% overload for one hour during factory testing. Therefore, abusing the machine by operating it under overload for extended periods will significantly shorten its lifespan. In routine management, uneven fuel delivery to the cylinders of a diesel engine will cause some cylinders to be overloaded and suffer damage. When a diesel engine is operating at its rated throttle, its operating speed should not be too low because high-boost engines have high thermal and mechanical loads.

From a thermal load perspective, when a diesel engine operates under such low-speed, high-load conditions, the total exhaust gas energy received by the turbine per unit time is reduced due to the low engine speed. This leads to a decrease in turbocharger speed, lower boost pressure, and insufficient air supply, resulting in poor combustion and increased exhaust gas temperature. Simultaneously, the turbine blades become contaminated due to poor combustion. Conversely, if the diesel engine operates at low load for extended periods, it exacerbates uneven fuel injection and poor atomization, causing unstable operation, poor combustion, and cylinder contamination. Low-temperature operation also significantly accelerates engine wear and reduces engine life.

Therefore, during low-load operation, the emergency blower should be automatically or manually activated to increase scavenging pressure.

2. How should a diesel engine be maintained during long-term parking?

A: If the diesel engine needs to be parked for an extended period, it can be periodically rotated using a turning gear, and the oil pump manually injected into the cylinders using the cylinder lubricator to ensure the cylinder walls are covered with lubricating oil, preventing rust on the piston assembly and cylinder liner surfaces.

To prevent deformation of the crankshaft and turbocharger shaft from prolonged storage, they should be rotated periodically and parked in different positions.

When the ambient temperature drops below freezing, all water should be drained from the cylinder, cylinder head cooling spaces, turbocharger turbine cooling jacket, and cooling water pipe system to prevent freezing and rupture of the cooling spaces and pipes. This is especially important when the engine is docked in winter. Raising the engine bay temperature would make this even easier.

When the diesel engine is not used for extended periods, the exhaust pipe (main chimney) outlet should be wrapped with tarpaulin to prevent rainwater from flowing into the flue and causing rust.