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What Are The Phenomena And Causes Of Diesel Generator Failure

Nov. 04, 2021

Common faults of diesel generators include difficulty in starting, abnormal smoke exhaust, weak operation, uneven speed, and failure to charge. The following is a description by Starlight Power combined with examples of domestic 135 and 105 series diesel generators.


Failure phenomenon:

1. There is no explosion sound in the cylinder, and the exhaust pipe emits white smoke or no smoke.


2. The exhaust pipe emits black smoke.


Test verification shows that in order to ensure that the diesel generator can start smoothly, four necessary conditions must be met: a certain speed, an unobstructed oil circuit, cylinder pressure, and fuel supply timing. Diesel generators are based on the above starting conditions, and the reason why diesel generators are not easy to start is inferred.


Reasons for failure:

1. The speed of the diesel generator is too low:

① The starting speed is too low. 

② The position of the pressure reducing device is incorrect or improperly adjusted. 

③ The valve clearance is improperly adjusted.


2. The oil and gas passages are not unblocked:

① The fuel tank is injected or the fuel switch is not turned on.

② When the diesel generator is started, the ambient temperature is too low.

③ There is water vapor or air in the oil passage.

④ When, the fuel injection nozzle cannot inject fuel.

⑤ The fuel pipe or diesel filter is clogged.

⑥ The air filter is too dirty or clogged.


3. Pressure difference in the cylinder:

① The matching gap between the piston and the cylinder wall is too large.

② The piston ring is broken or the elasticity is too small.

③ The intake and exhaust valves are not closed tightly.


diesel engine

4. Irregular supply:

① The injection time is too early (it is easy to cause the fuel injection pump to be killed) or too late.

② The distribution is not timely.


For the failure of the diesel generator to start or difficult to start, it is generally judged and tested based on the following different failure phenomena.


1. The speed of the diesel generator is too low when starting with electricity. For example, the start-up speed is extremely slow, mostly because the start-up motor is not working well, which does not mean that the diesel generator itself is malfunctioning. It is necessary to conduct a detailed inspection of the starting circuit to determine whether the battery has sufficient power, whether the wires are tight, whether the starter motor is working normally, and whether the air filter is blocked.


For manually-started diesel generators, if the pressure reducer is improperly positioned or adjusted improperly, improper adjustment of the valve clearance causes the valve to move against the piston, which is characterized by the fact that the crankshaft cannot rotate at a certain position, but it can be retracted. During this period, in addition to checking the pressure reducing valve and valve clearance, but also to check whether the timing gear meshing is correct.


2. The starting speed is normal, but there is no fire, the cylinder does not explode, or occasionally explodes, and the exhaust emits white smoke. The results show that diesel is unburned in the engine body and becomes steam to be discharged, or there is too much moisture in the diesel.


Check whether the ambient temperature during startup is too low, and then check whether there is air and water in the oil circuit. The way to check this kind of failure is to loosen the bleed screw on the diesel filter, the bleed screw on the fuel injection pump or the high pressure fuel pipe on the fuel injection pump, and rotate the diesel generator.


If there are bubbles, there is air in the oil supply system. The treatment method is to tighten the joints of various parts of the oil circuit, then loosen the bleed screw on the fuel injection pump, turn the crankshaft until the oil is free of air bubbles, then tighten the bleed screw and turn on the power. If you find that there is water in the diesel, you can also use the same method to check and find out the reason for the presence of water in the diesel, and replace the diesel in the fuel tank as needed.


If there is no air or moisture mixing in the diesel, continue to check the nozzle performance and fuel supply time for appropriateness. For a single-cylinder diesel engine, the working performance of the nozzle must first be judged.


Jiangsu Starlight Electricity Equipments Co.,Ltd. is one of the earliest manufacturers of generators and diesel generator sets in China. The company relies on high-quality products and good services. It has been widely recognized by users in many fields. At present, it can provide various specifications of diesel generator sets in the power range of 15KW-2500KW. For more details, please contact us with sales@dieselgeneratortech.com

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