Two reasons cause plunger pump overheating: one is heat generation due to mechanical friction. Since the moving surfaces are in a state of dry or semi-dry friction, the moving parts generate heat through mutual friction. The other is heat generation due to liquid friction. High-pressure oil leaks through various gaps into the low-pressure chamber, converting a significant amount of hydraulic energy into heat. Therefore, accurately selecting the gaps between moving parts, the oil tank capacity, and the cooler can prevent the pump from overheating and the oil temperature from rising too high. Additionally, a blocked return oil filter causing excessive return oil back pressure can also lead to high oil temperature and overheating of the pump body.

Piston pump oil leakage is mainly caused by the following reasons: (1) damage to the main shaft oil seal or defects or scratches on the shaft; (2) excessive internal leakage, causing increased pressure at the oil seal area, leading to seal damage or extrusion; (3) overly thin and long drain pipes, causing oil leakage at the sealing point; (4) loose external oil pipes of the pump, damaged pipe joints, worn-out or cracked sealing washers; (5) loose bolts of the variable regulating mechanism, and damaged seals; (6) sand holes or poor welding in the cast iron pump housing.