The front big end is the only bad symptom, it goes BANG BANG BANG BANG etc, only at medium to high revs does it reduce the noise
level. I have service
the injectors, so that is not the cause. The motor is set at an angle of 18-20 degrees and that may have been a contributing factor, as well as years of neglect before we rescued the vessel.
If we do repair the motor it is probably not a long term solution, as we need to address the shaft angle issue (rebuild the stern or get an gearbox
with an angled output). Hence we want to economise on the parts
as they are very difficult to obtain and most need to be brought in from Japan
by the supplier, the motor is so redundant. They said some parts
could be 3 to 6 mths to obtain and then some may not be available at all.
Now if it was a Yanmar
it may be a different story, but it is a Yamaha.