Basic Knowledge About Engine

1. What are the causes of unstable or insufficient piston cooling oil pressure?

Answer: The causes of unstable or insufficient piston cooling oil pressure may include:

1) Insufficient circulating oil.

2) Leaking or blocked oil pressure regulating valve of the lubricating oil pump.

3) Loose lubricating oil pipes, causing excessive oil loss inside the diesel engine.

4) Air entering the lubricating oil pump.

5) Overheating lubricating oil, causing diesel fuel to mix with the lubricating oil, resulting in excessively low viscosity.

If the pressure in the cooling oil system drops, the oil pressure regulating valve should be adjusted first. If the pressure still cannot be restored to the normal range, the diesel engine must be stopped for further inspection and troubleshooting.

If the piston cooling oil outlet temperature of a certain cylinder rises, the cause should be identified immediately and restored as soon as possible. If the cause cannot be found immediately, the load must be reduced and the cylinder injection stopped, operating at reduced cylinder capacity. Simultaneously, close monitoring of the cylinder's movement is necessary to prevent cylinder scoring or seizure.

2. What causes insufficient lubricating oil pressure? A: The reasons for insufficient lubricating oil pressure include:

1) A broken pressure regulating spring in the lubricating oil pump causes the pump to circulate on its own, reducing the oil supply to the system and lowering the oil pressure.

2) Insufficient circulating oil volume.

3) Air entering the lubricating oil system.

4) Damaged bearings or excessive clearance causing lubricating oil leakage.

5) Loose pipe connections or ruptured oil pipes causing significant lubricating oil loss.

6) The lubricating oil pump inlet valve is partially closed due to vibration.

7) The lubricating oil filter is too dirty, causing excessive pressure drop.

8) Damage to the machine's oil pan or lubricating oil circulation cabinet, resulting in a drop in the circulating oil level.

9) Overheating of the lubricating oil, or excessively low viscosity.

If the lubricating oil system pressure is insufficient, the oil pressure should be increased using the lubricating oil pump pressure regulating valve. If the pressure still cannot be increased to the normal value, the cause must be identified and repaired immediately; otherwise, serious machine damage may occur. If the oil level drops suddenly, stop the engine and investigate the cause.

3. What are the reasons for insufficient cylinder lubricating oil supply?

A: Insufficient cylinder lubricating oil may be caused by the following:

1) A malfunctioning check valve in the cylinder lubrication connector, causing backflow of combustion gases and affecting lubrication.

2) The lubricator's lubrication volume is set too low.

3) The lubricator's transmission mechanism is loose or malfunctioning.

4) Damaged lubricator pipe joints causing oil leakage.

5) Air in the lubrication system.

6) A clogged lubricator suction filter or clogged lubrication system.

The lubricator must be inspected regularly; shake the lubricator to check if the lubrication supply is normal. During navigation, watch personnel should closely monitor the lubricator's operation and lubrication volume. If an interruption in cylinder lubrication is detected, reduce engine speed or stop the engine to troubleshoot the problem.

4. What are the reasons for a low-pressure lubricating oil alarm? A: Recently, some newly built ships have installed main engine oil low-pressure alarms, mainly used to warn of dangerous situations such as oil pressure loss in the exhaust gas turbocharger (not with its own pump lubrication) and the main engine itself. Sometimes, it can also be used to automatically shut down the main engine when oil pressure is low.

1) Reasons for the exhaust gas turbocharger oil alarm signal:

(1) No oil in the tank or a malfunction in the turbocharger oil pump. The fault should be quickly identified and eliminated.

(2) The turbocharger oil filter is too dirty, causing excessive pressure drop. The filter shaft should be rotated to scrape away the dirt.

(3) The turbine oil pump motor start control line is de-energized due to vibration, causing the pump to stop.

2) The main engine oil low-pressure alarm signal generally indicates:

(1) Insufficient oil level in the oil circulation tank or a malfunction in the oil pump itself.

(2) Air is drawn into the system by the oil pump.

(3) Leaks at pipe connections or damage to oil pipes, causing oil loss. (4) The lubricating oil is heated too high or its viscosity is too low.

(5) The lubricating oil filter is severely clogged, or the pressure drop is too large.