Key points in maintaining an automotive engine lubrication system: 1. Check the radial clearance between gears and the pump housing: Remove the pump cover, select a gear tooth opposite the meshing tooth, and measure the clearance between the tooth tip and the pump housing using a feeler gauge. Rotate the gear and measure the clearance of other teeth in the same way. If the radial clearance exceeds the allowable limit, replace the entire oil pump assembly. 2. Check the axial clearance between gears and the pump cover: After removing the pump cover, place a straightedge along the centerline of the two gears on the pump body, then measure the clearance between the gear end face and the straightedge using a feeler gauge. If the clearance exceeds the allowable limit, replace the entire oil pump assembly. 3. Check the gear meshing clearance: Remove the pump cover and measure the side clearance of the driving gear and driven gear on the meshing side using a feeler gauge. If it exceeds the allowable limit, replace the entire oil pump assembly. 4. Check the fit clearance between the driving shaft and the shaft hole: Measure the diameter of the oil pump driving shaft and the bore diameter of the driving shaft hole in the pump body separately, then calculate the fit clearance. If the fit clearance exceeds the allowable limit, repair or replace the component. 5. Check the fit clearance between the driven shaft and the bushing hole: Measure the diameter of the oil pump driven shaft and the bore diameter of the bushing separately, then calculate the fit clearance. If the fit clearance exceeds the allowable limit, replace the bushing. 6. Check the oil pump pressure relief valve: Common faults of the pressure relief valve include sticking, leading to excessively high or low oil pressure. During inspection, remove the pressure relief valve, clean the valve hole and valve body, and install the pressure relief valve ball (or plunger) into the valve hole. It should move smoothly without sticking. Check the opening pressure of the pressure relief valve on a test bench to ensure it meets the standard.
