A curved beam car, the owner said that he was driving slowly and suddenly heard a strange sound from the car, which sounded very abnormal.

After picking up the car, first start the vehicle, you can hear a strange sound when idling, this sound I have not encountered in the usual maintenance, it sounds like it is coming from the crankcase, left or right can not be determined.

Check it from the magneto side first, after all, there is no need to put oil, remove the foot frame, and remove the screws less. Open the magneto side cover, check to start the small chain and start the overrunning clutch swing bead without finding anomalies. Considering that the sound is only in the engine running process, so use the starting lever to drive the engine to rotate, and sure enough, this sound appeared, making a "cluck" sound. Put the magneto rotor on the crankshaft, rotate the magneto, the sound is slightly transmitted to the hand through the vibration of the rotation, although weak but obvious, but can not see where the problem is.

After opening it, everything seems to be normal from the outside, and there is no abnormal situation, so what should we do? So I used the starter lever to spin the engine again and make that strange sound come out again to see where it was happening. When rotating, I suddenly saw that the small chain was rotating, but the oil pump driving gear did not move, what happened? What an anomaly! Remove the tension arm and tension wheel, turn the motor oil pump drive gear by hand, can not turn, the oil pump is stuck, the fault point is here, the oil pump is stuck, resulting in the small chain in the oil pump drive gear skip teeth slide, resulting in abnormal sound. This sound is very abnormal, so it will scare the owner to send to repair. Disassemble clutch side cover, clutch, oil pump, go straight to oil pump. The oil pump is removed and decomposed, and a black something like a carbon block is found stuck in the gear of the oil pump. This thing is like the residue after the wear of the clutch piece. When the clutch piece is removed, it is found that there is a very serious wear. The reason for this failure, I estimate is that the residue of the clutch after serious wear enters the oil pump along with the oil, resulting in the oil pump stuck, the chain teeth skip. Oil pump can not rotate, will not be able to establish effective oil pressure, the whole car oil lubrication will fail, if not the owner alert, timely repair, and then face is the engine due to lack of oil and cylinder, then the loss is greater!

Replace the new oil pump teeth, oil pumps, clutch pieces, the most important thing is to clean the crankcase and oil filter to help the owner, test after loading, abnormal sound disappeared, oil pressure normal, troubleshooting.

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