Sterntube Seals

causes of leakage

excessive wear seal lips
hard and/or cracked seals due to overheating or excessive operating hours
broken or damaged seal springs (in drydock only)
foreign bodies under seal lips (fishing line, sand, dirt from hull blasting etc)
damage to seal housing
seal liners excessively grooved
pitting corrosion in liners
excessive clearance between sterntube bearings and propeller shaft. Vibration can cause pumping effect of oil or water past seals.

damaged gasket or 'O' ring on liner (aft seal)
damaged 'O' ring between liner and clamp ring (forward seal)
excessive eccentricity on liners
wrong oil in system (possible corrosive effect on seals)
liners machined under minimum permissible size
damaged housing gaskets
incorrect sealing ring material
incorrect sealing ring material used in conjuction with bio-oil (we recommend pod seal rings).