For many highly intensified diesel engines, because the piston always works under high temperature and pressure, it is prone to cylinder pulling, melting or explosion. In order to solve this kind of I-star problem, most high-strength diesel engines are equipped with piston oil cooling nozzles (fig. 3-54). The piston pin and connecting rod bearings are lubricated by cooling the oil at the bottom of the upper plane of the piston.

Special attention should be paid to the maintenance of diesel engines with piston oil cooling nozzles.

(1) In the mounting hole of the oil nozzle, a rubbing one-way valve for controlling the oil injection is generally installed. During maintenance, attention should be paid to the installation direction of this one-way valve to avoid reverse installation.

(2) The nozzle position of oil cooling nozzle is very sensitive to the cooling effect of piston.

Therefore, attention should be paid to the position during installation to avoid abnormal damage of piston caused by misalignment of nozzle.

(3) If a cylinder of a diesel engine always suffers from piston pulling cylinder or burning and melting faults in the course of use, it should be checked whether there is a problem with piston oil cooling nozzle when there are no other factors affecting it.