Cover the valve gear with a clean cloth to prevent dirt getting into the working parts of the engine.
If you follow the above instructions, the oil seals should work properly. Also watch the video below for an example of the installation process.
Over time, the seal lip(s) will wear a shallow groove into the shafting due to the pressure the seal imposes upon it. Visible scoring on the shaft indicates a genuine possibility that the seal will not perform as well as intended. The potential for lubricants leaking out and particulates working their way through the seal drastically increases when placed over a worn location.
Refit all the components in the reverse order of dismantling.
Viton®
High level of chemical resistance
High temperature resistance