According to the location of oil leakage, the reasons are different. 

1.Triangular cover edge oil leakage, screw is not tightened or triangular cover plane processing unqualified, this situation is rare ; 

The oil leakage at the joint between the oil pump and the motor is specifically the oil leakage at the oil seal. The reasons are as follows : a.the motor line is reversed, causing the oil pump to reverse, and the oil inlet valve is closed, the positive pressure causes the oil seal to break, resulting in oil leakage ( common ) ; b.oil surface height more than 1m pump ; the oil temperature exceeds the heat resistance of the oil seal or the oil is not suitable for the oil seal material, resulting in oil seal damage and oil leakage