The cause of the diesel engine low oil pressure 1. The fitting generator clearance of bearing and the crankshaft is too big, namely wear and the crankshaft bearing shell is too large; 2. Various bushing and shaft wear is too large; 3. Cooling nozzle or oil pipe leakage; 4. Oil pump work failure; 5. The oil pressure sensor failure; 6. High oil temperature caused by oil cooler dirty; 7. The oil of poor quality.