[MikeK]

The "soak" routine goes back to the days when shaft seals were made from oakum, a hemp or jute fiber cord that would swell as it absorbed hydrocarbons to saturation.

Soaking too long was never good, you only wanted to insure complete oil wetting of the fiber surfaces, not saturation penetrating to individual fiber cores that would cause swell before inserting, or 'packing' the space you wished to seal.

Misunderstanding of how the seal works led to the belief that prolonged soak was necessary to instil sufficient lubricant to prevent friction burning of the fiber surface when the shaft first starts turning. That complete soak through will occur without fear of friction burning the surface if the complete, oiled final assembly has a few hours to sit before running the shaft.

Many 'modern' cord seals are synthetic material like nylon or teflon fiber that do not swell. That low friction external fiber is woven around a core of material that does swell. They are best installed dry and oiled afterwards, or freshly oiled and immediately placed before the desired pressure sealing core swell occurs.

Unfortunately many suppliers that buy bulk seal cord, then cut it and repackage for specific engines, include instructions based on old wives tales (actually old mechanics tales) telling you to soak the stuff overnight. For the tightest fit you do not want all the swell to occur before placement.