Farmers familiar with diesel engines generally know that the fuel injector is one of the three precision components in the diesel engine's fuel supply system. Its normal service life is over 1000 hours. However, due to improper use, it often wears out and seizes up after only a few hundred hours, or even tens of hours.
I. Main Causes of Fuel Injector Seizure:
① Unclean diesel fuel and impurities in the high-pressure fuel line cause wear on the injector needle valve assembly, resulting in incomplete closure and backflow of high-pressure combustion gases, burning out the needle valve assembly. Additionally, dirt on the injector's pressure regulating spring, tappet, and other parts can move to the upper part of the injector needle valve via the tappet, or cotton ropes or wires used to prevent oil leakage can enter the injector through the high-pressure fuel line, all of which can cause the needle valve assembly to seize.
② Overheating and poor injector cooling can also cause the needle valve assembly to seize. Delayed fuel injection timing, excessive scale or blockage in the cooling water channels, wear on the water pump impeller end face, and prolonged engine overload can all cause engine overheating. ③ Wear on the injection valve causes dripping when the injector stops injecting fuel, leading to carbon buildup on the nozzle and potential jamming. ④ Insufficient injection pressure causes high-pressure combustion gases to backflow into the combustion chamber. ⑤ During injector installation, missing or damaged gaskets cause air leakage, resulting in localized overheating and jamming of the injector. ⑥ Manufacturing defects, such as an overly tight fit between the injector mounting hole on the cylinder head and the injector itself, insufficient clearance between the needle valve body and the mounting hole on the cylinder head, or excessively deep machining of the injector mounting hole on the cylinder head.
II. Repair Method for a Jammed Injector: First, heat the jammed injector in diesel or engine oil. Then, remove it, wrap it in a cloth, and use pliers to clamp the needle valve and slowly move it to remove it from the needle valve body. Drip a small amount of clean engine oil into the needle valve body and allow it to move repeatedly until it moves freely within the body. If the sealing surface of the needle valve shows signs of burning, it should be polished with polishing compound. When grinding, pay attention to the amount of grinding paste used and the grinding time. After cleaning the bell valve assembly, install it on the injector and adjust the injection pressure before reuse.
