Yanmar 3JH4E, Operation Manual

Page: 20 / 142

A new Yanmar diesel engine must be
operated at suitable speeds and power
settings during the break in period to make
the sliding parts, such as piston rings, break
in properly and to stabilize engine
combustion.
During the break-in period, the engine
coolant temperature gauge should be
monitored, temperature should be between
71˚ - 87˚C (160˚ - 190˚F).
During the first 10 hours of operation, the
engine should be run at maximum rpm
minus 400 - 500 rpm (approximately
60 - 70% of load) most of the time. This will
ensure the sliding parts break-in properly.
During this period, avoid operating at
maximum engine speed and load to avoid
damaging or scoring sliding parts.
NOTICE: Do not operate at WOT (wide open
throttle) for more than a minute at a time
during the first 10 hours of operation.
Do not operate the engine at low idle or at
low speed and light load for more than
30 minutes at a time. Since unburned fuel
and engine oil will adhere to the piston rings
when operating at low speeds for long
periods, this will interfere with proper
movement of the rings and the lube oil
consumption may increase. Low idle speed
does not allow break-in of sliding parts.
If operating engine at low speed and light
load, you must race the engine to clean the
carbon from the cylinders and fuel injection
valve.
Perform this procedure in open waters:
• With the clutch in NEUTRAL, accelerate
from the low speed position to the high
speed position briefly.
• Repeat this process five times.
Once past the initial 10 hours until 50 hours,
the engine should be used over its full
operating range, with special emphasis on
running at relatively high power settings.
This is not the time for an extended cruise at
idle or low speed. The boat should be run at
maximum speed minus 400 rpm most of the
time (approximately 70% load), with a 10
minute run at maximum minus 200 rpm
(approximately 80% load) every 30 minutes
and a 4-5 minute period of operation at WOT
(wide open throttle) once each 30 minutes.
During this period, be sure not to operate
your engine at low speed and light load for
more than 30 minutes. If operating engine at
low speed and light load by necessity, just
after the low idle operation, be sure to race
the engine.
To complete engine break-in, perform After
Initial 50 Hours maintenance procedures.
See Periodic Maintenance Schedule on
page 57.
PRODUCT OVERVIEW
14 JH4 Series Operation Manual