1. The spring falls off or shifts
phenomenon
The oil seal spring is separated from the sealing lip and loses the pre-tightening force.reason
：No special tools were used during installation, causing the spring to eject due to mechanical impact.
The oil seal is improperly stored and the spring pre-installed position is loose.
solve
：Use an oil seal installation tool with a guide sleeve (e.g. SKF TTOOL series).
Check whether the spring is stuck in the groove of the sealing lip before installation.
2. Sealing lip flanging
phenomenon
: The oil seal lip is turned out and in poor contact with the shaft surface.reason
：The shaft end is not chamfered, and the lip is deformed due to forced pressing.
Installation direction is incorrect (e.g. with the dust lip facing the media side).
solve
：Make sure that the chamfer of the shaft end is smooth (roughness Ra≤0.8 μm).
Confirm the direction of the oil seal: the main sealing lip faces the sealed medium (such as the transmission oil seal main lip faces inward).
3. Shaft surface damage
phenomenon
Shaft scratches cause accelerated wear on the lip of the oil seal.reason
：The surface roughness of the shaft exceeds the standard (the oil seal requires Ra 0.2-0 μm).
Hard particles (such as metal shavings) are embedded in the sealing lip.
solve
：Install the front polished shaft surface and apply grease protection.
Clean the shaft and oil seal to avoid contaminants from entering.