Analysis on the cause of abnormal sound of crankcase of underground scraper?

When the underground diesel engine scraper is running at high speed, it makes the muffled sound of "click, click", which is especially obvious when the throttle is suddenly reduced, which is caused by the axial clearance of the main shaft tile. 

Along the cylinder are similar to the sound of a small hammer tapping iron block, exhaust pipe blue smoke (accompanied by burning oil phenomenon), with a long handle screwdriver against the cylinder body is easier to hear, 

it can be determined that the piston ring side gap is too large or ring broken.

In the full length of the scraper cylinder to hear the dull "empty dong, empty dong" knocking sound, and open the oil port cover found that there are bubbles (indicating that there is leakage phenomenon),

 which is caused by the piston and cylinder liner clearance is too large; If you hear the "ga, ga, ga" crash sound in the same part slightly in the direction of the crankshaft, it is the knocking sound caused by the distortion

 of the connecting rod in the work,

 and the latter two sounds are more obvious when changing the diesel engine speed, and it is easier to distinguish.

When the diesel scraper suddenly changes the load, a short dull knocking sound can be clearly heard near the crankcase, and changes sharply with the increase of load or speed, and the sound increases, and it is not obvious when there is no load. This is caused by the excessive wear of the connecting rod shingle and the connecting rod journal. If a cylinder of the diesel engine is cut off, if the abnormal sound immediately disappears, it indicates that the connecting rod tile of the cylinder is ringing.