Yanmar 6LY3 series Service Manual page 309

Troubleshooting by Symptom
12/05
Trouble symptom
Black exhaust smoke.
Faulty fuel injection nozzle.
Faulty combustion because
of insufficient intake air
volume.
Faulty combustion because
of the blow-by gas and the
decreased compression air
pressure.
Miscellaneous.
6LY3 Service Manual
Causes
Faulty valve seat.
Sticking needle valve.
Wear of seat.
Clogged fuel injection
hole(s).
Decrease in fuel opening
pressure.
Clogged air cleaner.
Decrease in intake air
pressure.
Charging air temperature is
too high.
Engine room is not
ventilated.
No valve clearance.
Faulty contact of the intake /
exhaust valves and seats.
Seized main moving parts.
Wear of the piston ring.
Sticking piston ring.
Engine overloaded.
The injection timing is
improper.
© 2007 Yanmar Marine International
TROUBLESHOOTING
Corrective action
Check the fuel spray
condition with a tester. If a
malfunction is found, send it
to the FIE shop for service or
replacement.
Clean or replace.
Check the turbocharger.
Clean the blower of
turbocharger.
Check the impeller of the
seawater pump. Check for a
clogged seawater line and
for dirt in the intercooler core.
Check the ventilation.
Readjust the valve
clearance.
Lap the valve and seat.
Replace valve if necessary.
Disassemble and check.
Replace if necessary.
Check and replace.
Check and clean or replace.
Check around propeller and
boat hull.
Check the injection timing
control and condition. If the
timing is incorrect, reinstall or
replace the timer.
Remarks
See Fuel Injection Nozzle
Components and Functions
on page 6-26.
See Troubleshooting the
Fuel Injection System on
page 6-24.
See Turbocharger
Components and Functions
on page 9-4.
See Seawater Pump
Components and Functions
on page 7-6.
—
See Service Standards on
page 14-3.
See Inspecting Intake /
Exhaust Valves and Valve
Guides on page 5-30.
See Engine on page 5-1.
See Measuring the Piston
Rings on page 5-38.
See Measuring the Piston
Rings on page 5-38.
—
—
13-19