Yanmar 3YM30 bell housing oil leak on Oceanis 37

[Rob Heath]

Our Yanmar 3YM30 has developed a slight oil leak, you can see a drip on the bottom of the bell housing at the back of the engine on our 2009 Oceanis 37. Engine hour are just over 900, and the leak is a ~ one teaspoon over ~ 5 hours.
I believe this relates to a failing seal on the crank shaft.
Has anyone tried to change this seal without removing the engine? Or do I just accept it's a minor inconvenience to mop out the bilge after a long motor?
Regards Rob

 

[kloudie1]

Could be a leak from the transmission front seal also.. Both can be canged without major disassembly but the engine would have to be moved forward about a foot away from the transmission for access to either/ both seals. not a trivial job. I would monitor the engine and gearbox levels carefully ..

 

[Davidasailor26]

Could be a leak from the transmission front seal also.. Both can be canged without major disassembly but the engine would have to be moved forward about a foot away from the transmission for access to either/ both seals. not a trivial job. I would monitor the engine and gearbox levels carefully ..

Good point that it could be the transmission, but unless the camera is distorting the color that looks pretty black. My transmission oil never looks that dark; my engine oil certainly does, so I would guess engine side.

 

[Rob Heath]

Thanks both,
I'm pretty certain it is engine oil. The transmission oil is clear, and the dripping is black. The levels in both are fine. Over this season (~100 engine hours) I haven't noticed the level dropping in either: but is just a few teaspoons that has leaked.

 

[seadaddler]

I did change rear seal lots of labor yes move forward to clear tranny remove tranny and lots of other stuff
Yes need to remove many things so engine moves forward and fly wheel very heavy putting back on and everything came off rear laying down on my 07 H-36 but needed go from forward to put fly wheel back on.
Not really hard low $ for part like I said lots of labor time removing lots of things so engine moves forward.