Diesel engine piston cooling nozzle role is: forced cooling of the piston, piston, piston rings, cylinder liner friction pairs, strengthen the cylinder seal, clean burning carbon. Engine piston cooling nozzle is usually mounted on the engine main bearing lubricating oil channel, in order to maintain the main oil lubrication pressure engine piston cooling nozzle respectively single ball valve, through the damping hole type. According to the piston cooling nozzle of the agency we in the repair, in particular, to pay attention to the piston cooling nozzle valve opening pressure, the damping pressure (about 1.5 kg, not less than 0.5 kg).

When the piston cooling nozzle is under pressure, the piston will not be able to get a timely cooling. With increasing the temperature of the engine, piston thermal expansion, so that the piston top gap space becomes small, the will and the valve impact, the clearance between the piston and the cylinder becomes small friction intensified, causing cylinder, cylinder sticking accident. Therefore, it is very important to ensure that the piston cooling nozzle oil spray hole is open and has a good sealing performance and good injection ability. In the normal use of the engine, in a "Three Guarantees" cycle, the piston cooling nozzle usually does not appear above, but after the engine overhaul cycle, the piston cooling nozzle must be replaced, to ensure that the engine can work.

Particularly noteworthy is that in the repair process, maintenance personnel often take plug connected oil crossing, using pump check the piston cooling nozzle is smooth, while ignoring the piston cooling nozzle injection pressure detection. Above is the problem we met in the actual equipment maintenance, similar fault engine Youdao Yici F6L912 air cooled diesel engine, Cummins NT855 water-cooled diesel engine. Should pay attention in the maintenance.