What Are the Causes of Low Oil Pressure in Diesel Engines?

[Brooks]

Low oil pressure in diesel engines may be caused by insufficient oil volume, excessively high engine temperature, malfunction of the oil bypass valve, or a clogged oil filter. Low oil pressure can lead to severe engine wear and significantly reduce its service life. Below is a detailed explanation: 1. Insufficient oil volume: If the oil volume is insufficient, the oil pump's pumping capacity will decrease, or it may fail to pump oil due to air ingress, resulting in reduced oil pressure. This can cause increased wear on the crankshaft and bearings, as well as the cylinder liners and pistons due to inadequate lubrication. 2. Excessively high engine temperature: Factors such as excessive scale in the engine cooling system, poor heat dissipation, prolonged overloading, or delayed fuel injection timing can cause the engine to overheat. This accelerates the aging, degradation, and thinning of the oil, leading to leakage through various clearances and a drop in pressure. 3. Malfunction of the oil bypass valve: The oil bypass valve is designed to maintain normal oil pressure in the main oil passage. If its pressure-regulating spring weakens or is improperly adjusted, or if the sealing surface between the valve seat and the steel ball wears out or gets stuck, the oil pressure will decrease. 4. Clogged oil filter: When the oil filter is clogged and unable to allow oil flow, the bypass valve located at its base opens, allowing oil to bypass the filter and enter the main oil passage directly. If the opening pressure of the bypass valve is set too high, it may not open promptly when the oil filter is clogged, causing the oil pump pressure to rise, increasing internal leakage, and subsequently reducing oil pressure.