Causes of failure:
1. Oil seal falls off or oil seal defect leaks.
2. Loose main shaft causes oil seal leakage.
3. Leakage on the joint surface, loose joints of oil inlet and return pipes
4. Too tight belt installation causes wear of main bearing.
5. Casting or processing defects.
Failure judgment and troubleshooting methods:
1. Check whether the oil seal is cracked, whether the inner lip is cracked or flanging. If any of the above conditions are found, it should be replaced; check whether the joint surface between the oil seal and the main shaft is scratched or defective, and if there are scratches and defects, it should be replaced. Check whether the oil return is unobstructed. If the oil return is not smooth, the crankcase pressure is too high, causing the oil seal to leak or fall off. The oil return pipe must be small in diameter, not twisted, not bent, and the oil return is smooth. Check the matching size of the oil seal and the box body, and replace those that do not meet the standards.
2. Move the main shaft with force to check whether the neck clearance is too large. If the clearance is too large, the bearing bushing and oil seal should be replaced at the same time.
3. Check the sealing condition of the gaskets at each joint, repair or replace the gaskets; check the oil inlet and return joint bolts and the box thread and tighten them.
4. Check and readjust the belt tightness, and press 10 mm with your thumb.
5. Check the defects in the casting or processing of the box (such as whether the oil return hole at the box installation is unobstructed), and repair or replace the defective parts.