Perhaps your friend is referring to the grease cup "seal",which is a small groove in the body of the grease cup,in which a there was possibly a small string of asbestos to stop the water pump grease from leaking past.A possible alternative may be a piece of plumbers hemp sting greased and rolled tight enough to fit in the groove on the grease cup body to make a seal as the cup is screwed down to prevent grease leakage.