2006 Yamaha f115 oil leak blow by base pressure

[Stageharbor]

I have a 2006 Yamaha f115 that runs pretty well but is leaking oil from the top crankshaft seal and spewing oil from the breather hose. Causing the engine to smoke. I put some key words in the title That I have heard thrown around for attention. Truth is I’m not sure what is going on. Engine has around 800 hours. Oil level is kept between the marks. Engine does do a-lot of idling. I did a cold leak down and all cylinders had less that 5% leakage? Any ideas? Carbon issue? Thanks in advance Brian

 

[Marine Services of Las Vegas]

Are you sure it is leaking from the top seal? The only way to see it is if you pull the flywheel. How much oil do you think? If you pull the air silencer and tip it into a canister? A little oil can be expected, also if you store the engine at a negative trim (trim down) angle it can cause the engine to smoke at start up. Also what was your working pressure (psi) when doing leak down?