Generator maintenance case: the fault phenomenon caused by the wrong adjustment of diesel generator set oil supply advance angle

Recently, we received a call from the user, saying that after the diesel generator set is started, there is a strange sound in the valve cover, and the speed increases, the sound increases, while the rhythmic heavy knocking sound in the cylinder. For this fault, the top Bo power professional after-sales technicians to visit the unit for maintenance, failure analysis shows that the phenomenon is generally due to the diesel generator set oil supply advance angle or valve clearance adjustment error.

 

Failure causes.

 

1, valve foot ringing in the cylinder.

 

2, valve clearance is too large.

 

3, valve stem and valve guide clearance is too large.

 

4, the valve is jammed.

 

5、Severe wear of the camshaft.

 

6、Breakage of valve spring.

 

7、The oil supply advance angle is too small.

 

Troubleshooting methods.

 

1, remove the valve cover, check the valve clearance, turn the flywheel in the "0" scale so far, at this time, the first cylinder of the diesel engine is exactly in the compression stroke of the upper stop, check the intake and exhaust valve clearance of the first, second and third cylinders respectively with the plug ruler, no abnormalities were found. Continue to rotate in the direction of the diesel engine to the fourth cylinder compression stroke on the stop, and began to check the second cylinder exhaust valve, the third cylinder intake valve, the fourth cylinder intake and exhaust valve clearance, the results found that only the third cylinder intake valve is not correct, the clearance is about 0.6mm, after adjustment, start the diesel engine to 700r/min, the rhythm of the valve chamber casing back to normal.

 

2, according to the requirements of the diesel engine, the oil supply advance angle check, the results found that the first cylinder of the high-pressure oil pump just began to supply oil, the diesel engine oil supply advance angle of 10 °, loosen the high-pressure oil pump drive disk of the two set screws, reverse the disk car to the pointer to the flywheel scale 28. so far, tighten the two screws, and then start the diesel engine, the heavy knocking sound in the cylinder disappeared.