Diesel Generator Oil Pump Inspections

Whether the lubrication system can ensure good lubrication conditions when the diesel generator set is working. Although it is related to factors such as whether the oil passage is unblocked and whether the filter is functioning, the most important and decisive factor is whether the performance of the oil pump is good. Therefore, when the internal combustion engine is maintained, the oil pump should be inspected and repaired.

1) Common faults of the oil pump

There are three common failures of oil pumps:

①Abrasion of the tooth surfaces of the main and driven gears, gear shafts, pump body and pump cover;

②Fatigue peeling of tooth surface, cracks and breaks of gear teeth;

③The spring of the pressure limiting valve is broken and the ball valve is worn.

(2) Inspection of the meshing clearance of the driving and driven gears

The increase in the gear meshing gap is caused by the friction between the gear teeth of the oil pump.

The inspection method is: remove the pump cover, use a thickness gauge to measure the gap between the two teeth at three points where the active and passive gears mesh with each other at 120°.

The normal value of the meshing gap between the driving gear and the driven gear of the oil pump is generally 0.15~0.35mm, and each model has clear regulations. For example, the 4135 diesel engine is 0.03-0.082mm, the maximum is not more than 0.15mm, and the 2105 diesel engine is 0.10~0.20mm. , The maximum does not exceed 0. If the gear meshing gap exceeds the maximum allowable degree, new gears should be replaced in pairs.

(3) Inspection and repair of the working surface of the oil pump cover

The working surface of the oil pump cover will have a depression after being worn, and the depression should not exceed 0.05m. The inspection method is: use a thickness gauge and a steel ruler to measure. Stand the steel ruler side on the working surface of the pump cover, and then use a thickness gauge to measure the gap between the inspection gap between the working surface of the pump cover and the driven gear of the steel ruler. If it exceeds the specified value, place the oil pump cover on a glass plate or flat plate and smooth it with valve sand.

(4) Inspection and repair of gear end face clearance

The clearance between the end faces of the main and driven gears of the oil pump and the pump cover is the end face clearance. The increase in the end face clearance is mainly caused by the friction between the gear and the pump cover in the axial direction.

There are two inspection methods as follows.

① Use a thickness gauge and a steel ruler to measure: the gear end face clearance-the pump cover recession + the clearance between the gear end face and the joint surface of the pump body.

②Fuse method Put the fuse on the gear surface, install the pump cover, tighten the pump cover screws and then loosen it, take out the squashed fuse, and measure its thickness. This thickness value is the end face gap. This gap is generally 0.10~0.15mm, such as 0.05~0.11mm for 4135 diesel engine; 0.05~0.15mm for 2105 diesel engine.

If the end face gap exceeds the specified value, there are two repair methods:. Use thinner gaskets to adjust; ①Grinding the joint surface of the pump body and the surface of the pump cover.

5) Inspection of tooth tip clearance

The gap between the top of the oil pump gear of a diesel generator set and the inner wall of the pump casing is called the tooth tip gap. There are two reasons for the increase of the tooth tip clearance: ①The clearance between the oil pump shaft and the shaft sleeve is too large; ②The clearance between the center hole of the driven gear and the shaft pin is too large. As a result, friction between the top of the gear and the inner wall of the pump cover causes the tooth tip clearance to be too large.

The inspection method is to insert a thickness gauge between the top surface of the gear and the inner wall of the pump casing for measurement. The tooth tip clearance is generally 0.05~0.15mm, and the maximum is not more than 0.50mm, such as 0.15~0.27mm for 4135 diesel engine; 0.3~0.15mrno for 2105 diesel engine

If it exceeds the specified allowable value, the gear or pump body should be replaced.