Yam 9.9 blow by

[23Hourston]

Hey guys google is not my friend on this one. New to me 2011 yam high thrust
getting a fair bit of blow by out the dip stick when removed. 125 psi in both holes. Little bit of smoke when ya gun it. Thinking crank case breather plugged but I can t find it. Anyone been dealing with something similar.

 

[23Hourston]

Beginning to think it’s normal

 

[gunnerlove]

Hit it hard with seafoam.

 

[23Hourston]

Hit it hard with seafoam.

I found the breather it seems to be operating normally

 

[gungadin]

do a leak down test

 

[trophywife]

too much oil?

 

[TinnyTime]

my merc 9.9 was the same, removed the dip stick and it feels like major blow-by..
.....but it has good compression sooooo I came to the realization that its just the nature of a small small motor, with tiny crankcase volume,
The pistons motion (even tho theyre counter-acting) casuses that air pumping sensation out the dip stick hole..

dont be alarmed like I was

 

[Fixit]

Run some Yamaha ring free through it
If the rings are a little gummy it will help.... if the rings are shot it won’t make a difference but cheap to try