bus 911 pump plunger , Iran

The diesel pump plunger of the 911 bus, typically installed on Mercedes-Benz OM457 or OM447 engines, is an ultra-precision component in the inline fuel injection system. The plunger diameter in these engines ranges from 9 to 11 millimeters depending on the part number with a tolerance below 1.5 microns. The plunger material is hardened steel reaching 60 to 64 HRC for superior wear resistance against microscopic fuel contaminants. The delivery valve mounted above each pump cylinder is responsible for opening and closing the high pressure fuel path to the injector. The opening pressure of the delivery valve is typically set between 2 to 5 bars to prevent fuel dribbling after injection completes. The coordinated operation of the plunger and delivery valve creates precise injection timing with a uniform pressure profile across all engine speeds. Proper maintenance of these components directly affects fuel consumption and engine smoothness during operation.

The injector nozzle of the 911 bus is the final fuel circuit component that sprays high pressure fuel as fine droplets into the combustion chamber. The injection pressure for this nozzle ranges from 220 to 280 bars depending on the nozzle type (P-type or S-type). The nozzle tip typically has 4 to 6 holes with diameters of 0.2 to 0.3 millimeters for a proper conical spray pattern. Needle lift during injection is approximately 0.15 to 0.3 millimeters with an injection duration of 1 to 2 milliseconds. Failure symptoms of the injector nozzle include white smoke during cold starts and engine knocking at idle speed. Fuel consumption increases by over 30 percent with severe power loss when climbing steep hills. Fuel leakage from the injector leak-off return line exceeding 50 cc per minute indicates advanced nozzle wear. Injector nozzle replacement must always be performed as a complete set of six pieces to maintain engine balance. Regular calibration every 200,000 kilometers is recommended for optimal injector performance and fuel economy.You can order and buy bus 911 pump plunger from Iran by contacting us through whatsaap and email.
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