Some kind of gasket sealer? Has the engine been in bits before
Head was rebuilt and oil cooler has been offSome kind of gasket sealer? Has the engine been in bits before
or a old condomDiesel bug??
There's your clue, oil cooler, obviously a stupid attempt to seal what should be a self sealing fitting, probably one of the fittings on the cooler has no o-ring, some slack work there. That hunk of silicone could not get up to there from the sump but can get there from the return side of the cooler, fortunately the inlet side of oil filter.Head was rebuilt and oil cooler has been off