Why Is Piston of 150KVA Generator Sets Easy to Failure

by Dieselgenerator Tech ***

Piston is a small part of 150KVA diesel generator set, but it is one of the important parts of diesel generator. Because its working environment is relatively bad, it often has such and such problems. Let's take a look at what causes piston failure.


During use of 150KVA generator set, the easily worn parts of the piston are the ring groove, followed by the skirt and pin hole. There are usually several ring grooves on the piston, but the ring groove near the combustion chamber is the most vulnerable to wear. When the ring groove is greatly worn, more high-temperature and high-pressure gas will enter the crankcase and more engine oil will enter the combustion chamber. After the piston is damaged, it can generally be inspected by observation and judgment. When the exhaust pipe of diesel engine emits blue smoke or the power decreases, most of the faults occur in the ring groove or piston cup. When the diesel engine is idling, the sound of air leakage in the crankcase can be heard. It is difficult to repair the piston. When the piston is seriously worn, it is generally replaced with a new piston of the same model.

Generating set

A.Causes of the top of the engine plug hitting the cylinder head.

1.During maintenance or assembly, accidentally drop small screws, nuts or screws into the intake pipe or piston. Or suck in the cylinder during suction, or the small gasket is stuck under the cylinder head. When installing the cylinder head, it was not noticed to stay in the combustion chamber, and there was an abnormal noise after starting the engine, causing the piston crown to collide with the cylinder head.

2.Damage to the connecting rod pad will also cause the piston to touch the cylinder head. This kind of collision is inertial collision and is not caused by too long connecting rod or piston. Therefore, when turning the flywheel, the piston can not be found touching the cylinder head. It can only be heard when the diesel generator is running (the sound increases with the increase of rotating speed, and the sound is light at low speed).

3.When installing the connecting rod bearing cap, install the bearing cap reversely or install other connecting rod caps wrongly. Although the screw is tightened, the Bush is still oval (the connecting rod body and cover are processed in pairs and cannot be replaced). The rotation inertia causes the piston to hit the cylinder head, resulting in a light, brittle and solid "click" sound. There is still a noise after the oil is cut off, which does not weaken, and the cylinder head vibrates greatly. Therefore, special attention should be paid to this point during maintenance.

4.After the connecting rod bolt is loosened, it will also cause the piston to collide with the cylinder head. Qualified bolts shall be selected and tightened as required. It is forbidden to use old bolts.


B. Piston rubbing cylinder.

The piston surface is roughened due to dry friction; When the diesel generator is accompanied by a slight knock on the cylinder, metal deposits have been generated on the piston surface. At this time, if it is not repaired in time, the piston and cylinder liner will be locked.


1. Overload operation of diesel generator and problems in cooling system damaged oil film, resulting in cylinder pulling.

2. The lubricating oil is too thin to play an effective role in lubrication, or the failure of the lubrication system leads to the increase of the friction coefficient between the piston and the cylinder liner, resulting in cylinder pulling.

3. Improper adjustment of ignition time of diesel generator causes knock and deflagration of diesel generator, and too high temperature in diesel generator destroys the oil protective film, resulting in cylinder pulling.

4. Improper installation of piston or mismatched installation of piston and cylinder liner, and too large or too small clearance can also lead to cylinder pulling.

5. The air filter, lubricating oil filter and fuel filter of diesel generator set are not replaced and cleaned in time, which pollutes the working environment of the cylinder and leads to cylinder pulling.

6. The bending of the rod changes the running direction of the piston, resulting in cylinder pulling.

7. The piston ring is stuck and the piston ring is broken, resulting in cylinder pulling.

8. There is too much carbon in the generator set, and the fallen carbon enters the cylinder block, resulting in cylinder pulling.

Above are reasons of piston failure of 150KVA generator, when we use diesel generator set, if find any faults, we should stop the machine to do inspection and solve faults in time. So that can reduce machine damage.

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About Dieselgenerator Tech Advanced    ***

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Joined APSense since, December 21st, 2021, From Nanning, China.

Created on Jun 5th 2022 07:33. Viewed 125 times.


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