What are the reasons for the drop in oil pressure in diesel engines?
4 Answers
Reasons for the drop in oil pressure in diesel engines: 1. Insufficient oil quantity, making it difficult for the oil suction plate to draw oil; 2. Sticking of the pressure relief valve plunger steel ball; 3. Low adjustment of the preload force of the pressure relief valve spring leading to deformation and failure of the spring; 4. Severe clogging of the filter, obstructing smooth oil flow into the main oil passage; 5. Severe wear of the bearing bush causing large-scale peeling damage and excessive clearance; 6. Oil dilution. Functions of diesel engines: 1. Withstanding gas force and inertia force; 2. Supporting the weight of all machine components; 3. Forces from through bolts and connecting bolts; 4. Generating thermal stress due to varying temperatures in different areas.
I often help friends with car repairs and find that the most common cause of low oil pressure in diesel engines is insufficient oil volume, especially when the oil pan is leaking or piston rings are worn, causing rapid oil consumption. Naturally, the pressure drops when the oil level is low. Additionally, wear or seizure of the oil pump can directly reduce pressure—if the pump fails, it can't push the oil. When the oil filter is clogged, oil can't flow through, and the increased resistance causes pressure to drop. Excessive bearing clearance, such as wear on the main or connecting rod bearings, allows oil to leak, making it hard to maintain pressure. Sometimes, poor oil quality or contamination with impurities thins the oil viscosity, making it difficult to sustain pressure. If there's an oil leak in the system, like a cracked oil line or a failed gasket, the pressure will definitely drop due to oil loss. During inspection, first check the dipstick for oil level. If it's normal, examine the filter and oil pump. Regular maintenance and oil changes are key.
As someone who commutes daily in a diesel pickup truck, I believe that a drop in oil pressure is often due to neglecting the oil change interval. If the oil is overdue for a change, carbon buildup increases, viscosity decreases, and pressure drops. Long-term failure to replace the oil filter, leading to clogging, can also cause unstable oil pressure. Driving habits also play a role—for example, frequently operating at high RPMs heats up the engine, thinning the oil and making pressure more likely to drop. Checking is simple: if the oil level is low, just top it up with fresh oil; if the filter is the issue, replace it directly; if the bearings are worn, replacing the components can restore performance. Prevention is the best approach—check the oil level monthly, change the oil every six months, and avoid these problems. Safety comes first; if pressure drops, stop and repair immediately to prevent engine damage.
Having driven diesel vehicles for over a decade, the most common cause of oil pressure drop is excessive bearing wear, such as widened clearance in connecting rod or main bearings leading to inability to maintain oil pressure. Additionally, an aging oil pump or improper installation can result in insufficient oil delivery and low pressure. A clogged filter can also indirectly reduce pressure, and neglecting it during oil changes can lead to issues. Oil leaks in the system, like loose pipe connections or broken seals, will naturally cause pressure to drop. In severe cases, the engine may produce abnormal noises and smoke, requiring immediate repair. It's recommended that owners perform regular maintenance, use high-quality oil to minimize wear, and conduct simple checks with a pressure gauge to ensure readings meet standards.
