The occurrence of abnormal noise of the excavator engine is often related to the speed of the engine, the load the engine bears, the temperature of the engine, and the working cycle oil pipe of the engine. To find
1 The relationship between "exciter engine abnormal noise" and engine speed
The abnormal noise of the engine occurs at idle or low speed. The general causes are: the gap between the piston and the cylinder wall of the excavator engine is too large, or the piston pin is too tight, or the caterpillar engine tappet The gap between the guide hole is too large, etc.
The sudden noise of the excavator engine at a certain speed may be caused by: the engine crankshaft is broken, the piston pin bush is loose, or the camshaft timing gear of the engine is broken or the fixing nut is loose.
The abnormal noise appears when the excavator engine accelerates rapidly, which may be due to the following reasons: the connecting rod bearing is loose, the bearing bush is melted or the size is not matched, and the crankshaft bearing is loose or the bearing bush is burned, the piston pin is broken, the crankshaft is broken, etc .
2 The relationship between "excavator engine abnormal noise" and excavator load
The abnormal noise appears when a cylinder of the engine is misfired, and it will disappear after a while. The reason may be that the engine piston knocks on the cylinder, or because the connecting rod bearing is loose, or the piston ring leaks.
The abnormal noise appears when a certain cylinder of the engine is misfired, but the abnormal noise is getting louder, it may be because: the copper sleeve of the piston pin is loose, the taper of the piston skirt is too large, the piston pin pops out, and the connecting rod bearing cover is fixed The bolts have been loosened or the connecting rod bearing alloy has been melted and removed, etc.
If there is a misfire between the two adjacent cylinders of the engine, the reason for the abnormal noise of the excavator engine may be: the crankshaft bearing is loose.
3 The relationship between excavator engine abnormal noise and temperature
Low-temperature abnormal noise, the abnormal noise gradually disappears after the temperature rises. The reason for the abnormal noise of the excavator engine is: the gap between the piston and the cylinder wall is too large, or the engine oil pressure is low and the lubrication is not good.
High-temperature abnormal noise, the abnormal noise disappears as the temperature decreases. The reason for the abnormal noise of the Carter excavator engine is: the piston of the Carter excavator engine is deformed, or the gap between the piston rings is too small, and it may be caused by preheating caused by overheat .
malfunction repair:
1. After disassembly and inspection, it was found that the rocker arm of the exhaust valve of the third cylinder was broken, the upper half of the valve push rod was broken, the valve lock was damaged, and the valve fell into the cylinder. After removing the cylinder head, the exhaust that fell into the third cylinder was found The valve rod is stuck on the exhaust valve seat ring, and the valve head in the falling cylinder bumps the top of the third cylinder piston.
2. Updated the third cylinder exhaust valve, exhaust valve seat ring, valve lock plate, valve oil seal, valve spring, valve push rod and rocker arm, etc., and reinvented the third cylinder exhaust valve seat. Repair the damaged part, then install and debug correctly, and prepare to start the test machine.
3. However, in the process of driving the diesel engine with the starter motor, I still heard a "click, click" knocking sound inside the diesel engine. After several starts, this is the case. At the beginning, it was thought that the top of the piston may not be trimmed. Thoroughly, the edge of the head of the exhaust valve collided with the edge of the pit on the top of the piston, and there was an abnormal noise. To this end, the cylinder head was removed, and the top of the piston of the third cylinder was completely repaired. There is still a "tap, tap" sound inside the diesel engine.
4. When the diesel engine is driven by the starter motor, carefully observe the movement of the valve rocker arm. When it is found that the rocker head of the exhaust valve of the third cylinder has just pressed the valve, the "click, click" sound inside the diesel engine will follow. It can be seen that the abnormal sound is not due to the exhaust valve colliding with the piston. This is because the piston is at a position close to the bottom dead center. Further judgment, the problem may be between the camshaft and the tappet.
5. Remove the cylinder head, when the third cylinder exhaust valve tappet is taken out upward, the tappet has only a cylindrical object, and its bottom is left between the cam and the cylinder block duct.It is obvious that the internal The sound of "tap, tap" is due to the collision sound made by the bottom of the tappet after the break.
6. Remove the cover of the timing gear chamber of the diesel engine, and at the same time remove the oil pan and the intake and exhaust valve tappets of the fourth cylinder and the intake valve tappet of the third cylinder. Then pull out the camshaft and the third cylinder breaks The bottom of the column falls naturally.
7.Replace a new valve lifter and adjust the valve clearance before trying the machine.The abnormal noise inside the diesel engine is eliminated and everything is normal.
