What is the oil pressure of a diesel engine?
2 Answers
Diesel engine oil pressure is 3 to 5 units, and it is 1 unit at idle speed. A diesel engine is an engine that burns diesel to obtain energy release. Its working process is the same as that of a gasoline engine, with each working cycle also going through four strokes: intake, compression, power, and exhaust. In the intake stroke, a diesel engine draws in pure air. Near the end of the compression stroke, the diesel fuel is pressurized to over 10MPa by the fuel injection pump and then injected into the cylinder through the fuel injector, where it mixes with the compressed high-temperature air in a very short time to form a combustible mixture. Due to the high compression ratio of diesel engines, the air pressure in the cylinder at the end of compression can reach 3.5 to 4.5MPa, while the temperature reaches 750 to 1000K, exceeding the auto-ignition temperature of diesel. Therefore, after the diesel is injected into the cylinder, it mixes with the air and spontaneously ignites and burns almost immediately.
I often drive diesel vehicles, and the oil pressure is usually between 60 to 80 psi during cold starts, dropping to around 20 to 30 psi at idle when the engine is warm, and ranging from 40 to 60 psi during normal driving. The specific pressure depends on the engine model and the owner's manual, as older and newer vehicles differ. For example, my heavy-duty diesel feels safe when the gauge shows around 50 psi. If the pressure is too low—below 15 psi at idle—the oil pump might be faulty; if it's too high, exceeding 70 psi, the regulator valve might be stuck and needs checking. Temperature also has a big impact, with higher pressure in winter and more stability in summer. I make it a habit to regularly check the oil level and viscosity, choosing the right brand to avoid clogs. If the gauge needle becomes unstable or the warning light comes on, I get it fixed immediately to prevent rapid engine wear, which can damage the vehicle and cost more in the long run. Never skimp on regular oil changes and maintenance—it ensures safety and longevity.
