The diesel engine dealer that maintained my Yanmar for 10 of the last 19 years sells several types of diesel and has supported the commercial fishing
fleet in Puget Sound
since 1968. They also sell, repair, rebuild
, and maintain diesels installed in heavy dirt movers, farm equipment
, land based power generation.
They tell me they have thousands of Yanmar Marine
4 and 6 cylinder diesels installed in boats operating as recreational and commercial
He says Yanmar are bullet proof and will do 10,000 hours IF
- they are run at 70% - 90% of 24-hour rated power e.g. my 4JH2E would be 2200 t0 2900 RPM
- run the engine at 24-hour rated power for 5 minutes every three to five hours - my engine that is 3200 RPM
- IF you start the engine - run it up to full operating temperature for at least five minutes
- when shutting down the engine - IF it has been running at less than 80% power - then run it at full power for 10 seconds in neutral and then let it slow for another 10 seconds
- change the oil
- keep the air filter clean
They said no Yanmar ever fails if operated in the manner shown above
PS - their mechanic
installed new injectors at 400 hours. He wanted to demonstrate to me how fast a Yanmar NA 4 will run and how smoothly it ran. He pegged the tach for (4000 RPM) for 10 seconds and said the engine was probably doing 4200. I moved to the side deck
outside the cockpit
with pictures of dancing rods appearing in the cockpit
He has strobed 4JH engines at 4400 RPM. His last statement "Yanmar loves to run fast and hot - it makes them happy."
That was in 1995 and my 4JH2E is still running fast and happy with only oil
changes, new water
pumps, and valve adjustments. I have about 2800 hours on the engine and almost all of it has been 2300 - 2700 RPM.