Dee and I just returned from two weeks on our Bristol 29.9 cruising the coast of Maine
. I am happy to report that our little Yanmar
SB12 is running perfectly. The modifications that I made to the fuel
system are also working well. There were no air leaks
and no fuel leaks
. The engine
starts on the first rotation every time. We even had a situation with a low battery
(different story) and could just get the engine
to barely turn over. One compression
cycle and it was running!
I watched the oil
use carefully. Though the oil consumption
is way down from where it was before the rebuild
, the engine is still using some oil. Last year, before the rebuild
, it was using about 5 ounces of oil an hour. In the first thirty hours of operation after the rebuild, the engine used a bit less than a pint of oil. This equates to about 0.48 ounces per hour. In the next twenty hours of operation, the engine again used about a pint of oil, which equates to about 0.74 ounces per hour. In that twenty hour period, ten hours were spent trying to keep up with another, faster boat
. We ran the engine at a steady 2,850 rpm
. Normally we keep the engine at about 2,600 to 2,750 where it is much quieter. At 2,800 rpm
and above every bolt and bulkhead on the boat
vibrates and resonates. It's quite a cacophony of sound! But, this higher speed use may account for the increased oil use.
Does anyone understand the governor mechanism on this engine? If I put the throttle all the way forward, the engine goes to 3,000 rpm but settles back to 2,850. It then hunts a bit between 2,800 and 2,850. As noted, I don't like to run the motor
at it highest possible speed, but I'd like to know what keeps bringing the speed down from 3,000 to 2,850.