Reasons and solutions for abnormal noise in the crankcase of small loaders

As one of the common construction machinery in daily life and work, small loaders greatly improve work efficiency. However, after long-term use or lack of attention to maintenance, small loaders may still encounter some problems, such as abnormal noises in the loader crankcase.

When a small loader is running at high speed, if there is a "clunk, clunk" muffled sound, it is particularly obvious when the throttle is reduced, which is caused by excessive axial clearance between the main bearing pads; There is a sound similar to a small hammer lightly striking the iron block along the upper and lower parts of the cylinder, and blue smoke is emitted from the exhaust pipe (accompanied by oil burning phenomenon). It is easier to hear when using a long handled screwdriver to press against the cylinder block, indicating that it is caused by excessive piston ring clearance or ring breakage.

I heard a dull "empty thud, empty thud" knocking sound along the entire length of the loader cylinder, and when I opened the oil inlet cover, I found bubbles (indicating air leakage), which was caused by excessive clearance between the piston and cylinder liner; If you hear a "gah, gah, gah" impact sound slightly towards the crankshaft in the same part, it is the knocking sound caused by the twisting of the connecting rod, which swings during operation. The latter two sounds are more pronounced and easier to distinguish when changing the diesel engine speed.

When the loader suddenly changes the load, a short and dull knocking sound can be clearly heard near the crankcase, which changes sharply with the increase of load or speed, and the sound increases. It is not obvious when there is no load. This is caused by excessive wear of the connecting rod bearing, resulting in excessive clearance between the connecting rod bearing and the connecting rod journal; If a certain cylinder of the diesel engine is shut off and the abnormal noise immediately disappears, it indicates that it is the connecting rod bearing noise of that cylinder.