Yanmar engine break-in period?

[mjb]

OK - another question from a new owner for the group. What does
everybody recommend for the break in period on a new Yanmar 75hp
4JH3-TE engine (Turbo w/o intercooler)? The owner's manual does not
specify any special considerations. However, the site
http://www.yanmarhelp.com/i_seatrial.htm does provide some good
information. In summary, for my turbo engine the site recommends:

Sea Trial and Run In:
Start engine and maintain idle to 1500 rpm until the engine temperature
has stabilized.
Then push the 'go' lever until you have 50 - 60% rpm.
Increase the rpm by 200 rpm every 5 minutes or so until you have
reached full power.
Carry out a 30 minute full power run after reaching maximum rpm.
Monitor oil pressure, exhaust color, cooling water temperature.
Finally, when the engine rpm is correct, the seatrial is over.
For the next 5 hours running don't operate the engine at more than 85%
rpm or less than 2000 rpm and every 20 minutes change the rpm up or
down by 200 rpm.
When the 5 hours are up you can do what you like.

For normal operation, the site also recommends a 5 minute warmup to
achieve 60 deg C/140 deg F and then operate between 80% and 85% of max.
continuous rated RPM (which is 3700 for me). That means that after the
"run in" period, I should roughly stay between 3000 and 3200 RPMs after
a short warmup. The site and the owner's manual also recommend going
to max rpm for 10 to 20 minutes after every 2 to 5 hours of low rpm
operation to keep everything humming and clean.

The engine already has almost two hours from the yard and our sea trial
with the dealer (before I read the above information).

I'm inclined to follow the instructions above starting tomorrow - is
this overkill?

[Rick Donovan]

Our Westerbeke engine is not equivalent to your Yanmar, but I think in
general a break in of a new engine like you have written is about right. I
am also of the thinking that taking the time to run the engine for the full
recommended break in period, even though there is time on it now, is a good
idea.

What you are really trying to do is vary the load on the engine while all
the moving parts seat properly during the break in time period. What you
want to avoid as best you can is running at the same rpm for any length of
time. The varied loads assist in the seating of the piston rings to the
cylinder walls, valves to their valve seats, etc.

An extended run of 30 minutes at 100% seems a little extreme to me but if it
came from Yanmar they would know their products better than I do.

I would also recommend doing an early oil and filter change. The initial run
time is going to generate the most "metal debris" that is caused by the
break in of parts. When you get back to your home port would be soon enough
for the change. Don't forget to change the oil in the transmission at the
same time as that is also going thru break in.

Last thing to have checked before leaving the dealer is the tach accuracy,
ours was way off, and it is adjustable to get it fairly close. The dealer
should be able to do this adjustment if needed.

Enjoy your trip, the hard part is over now that the commissioning is done
and you have your new boat.

Happy Sailing!!!

Rick Donovan
Biddeford, Maine
Beneteau 473 #29
Turn the Page

[Ca...@aol.com]

We have the same engine. Wish we had such excellent information about breaking it in. At this point we are <10% (700 hrs) into it's life and following Yanmar's directions is obviously the best approach.

Cap in MD