Causes And Adjustments Of Diesel Engine Rotating Speed Unstable

1. Governor failure

   1. The elastic force of the governor spring is weakened. Insufficient spring force will reduce the speed regulation sensitivity of the governor, and the stable range of diesel engine speed will increase, fluctuating from high to low. At this time, the governor spring should be replaced.

   2. Excessive wear of the oil volume regulating arm of the oil pump and the fork groove of the governor lever, the drive disc and the thrust disc cone will cause the governor to lag behind, resulting in "swimming". At this time, the worn parts should be replaced to restore the normal fit clearance.

   3. The internal lubrication of the governor is poor, or the oil in the governor is too dirty, too thick, or the surface of the moving parts is damaged, causing sticking, which hinders the movement of the moving parts, and the speed regulation effect lags behind, resulting in unstable diesel engine speed. The elimination method is: clean the inside of the governor with diesel oil, replace the oil in the governor, repair or replace the damaged parts.

2. Oil failure

   1. The low-pressure oil circuit is blocked and the oil supply is not smooth. The elimination method is to clean and unblock the low-pressure oil circuit.

   2. Insufficient fuel in the fuel tank or blockage of the vent hole of the fuel tank cap causes insufficient fuel supply. Remedy Add enough fuel and clear the vent hole of the fuel tank cap.

   3. Cracks in oil pipes, loose pipe joints, etc. cause air to enter the low-pressure oil circuit. In addition, the wear of the hand oil pump of the multi-cylinder diesel engine can easily cause air to enter the oil circuit. The solution is to replace the oil delivery pipe and hand oil pump, and tighten the pipe joints.

   4. The oil outlet valve of the fuel injection pump is poorly sealed or the positioning screw is loose. Remedy: Grind the oil outlet valve and tighten the set screw.

   5. The fuel injector works unstable. Remedy: replace the injector needle valve coupling.

3. Fuel injection pump failure

   The wear of the plunger pair, the oil outlet valve pair and the wheel of the sub-cylinder of the multi-cylinder diesel engine causes the fuel supply pressure of each cylinder to be inconsistent, and the improper adjustment of the fuel injection pump will cause the fuel supply to be inconsistent. At this time, it should be readjusted on the test bench. In addition, the cylinder gasket of a certain cylinder of a multi-cylinder diesel engine is burned or the valve seal is not good, and the piston ring is excessively worn, which makes the cylinder compression poor or does not work, which will make the diesel engine speed unstable. The solution is to replace the cylinder head gasket, piston ring and grind the valve.