J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment More Engine Issues

I concur with Bob. One additional potential source is the oil pipe that runs in the back of the engine, but most likely the rear main seal. Check the fluid levels in both transmission and crank case.

The rear seal can be replaced by removing the transmission (you'll need to support the rear of the engine). The prop shaft coupling will need to be disconnected and shaft slid back about 3 inches to get the transmission out.

Remove the damper plate and unbolt the flywheel to remove it, You should be able to pry out the old rear main seal and replace it in place.

Download the Yanmar service manual in the main menu on this site under "info" then "Diesel Engine Maintenance"

ps - I believe you have hull number 54 not 56