Is this what the oil ring in an SB12 is supposed to look like? I see that in the YSM manual the oil ring has an internal copper expander. Of course, I also noted that the compression rings are keystone shaped and the SB12's are square - so there were improvement with the YSM. Can't find any "official" photos of the SB12's rings. See h t t p s : / / 1drv.ms/u/s!AiR9KzpBmPls1jH00mMFpKtjULbN

pmagistro:

I have Bristol 29.9 #46, built in 1978 and with the Yanmar SB12 motor. We had a long cruise this summer and I put over 60 hour on the engine in less than three weeks. Normally I do about that much in a season. My oil consumption is up, now estimated at about 3 oz per hour. I have no more smoke than normal, good power and good starting. I''m going to try the seafoam and next season I'll try harder to find straight weight oil. I've been running 15-40 instead of straight 30 as the 30 weight is hard to find.

I'm curious about your rebuild. Do you need to remove the motor to do this? What is the degree of difficulty for the job? I'm a pretty good mechanic and quite handy but not a pro. Do you think rebuilding the engine was worthwhile or, in retrospect, do you think it was overkill for the problem?

Homer Shannon
American Yacht Club
Newburyport MA