Yanmar 6LY3 series Service Manual page 301

Troubleshooting by Symptom
12/05
Trouble symptom
The starting motor rotates, but the engine will not start. (continued)
Low compression.
Air heater does not operate.
6LY3 Service Manual
Causes
Compressed air leakage
from intake / exhaust valves.
No clearance of intake /
exhaust valve.
Faulty cylinder head gasket.
Wear on the top of the
cylinder.
Piston ring wear.
Sticking of the piston ring(s). Disassemble and check. If
Loose cylinder head bolts.
Damaged valve spring.
Air heater terminal is
disconnected, loose or has
failed.
Air heater relay terminal is
disconnected, loosened or
has failed.
Faulty air heater.
Faulty air heater relay.
Fuse burned out.
(Air heater "A" or "B": 250A)
Clogged intake / exhaust
lines.
© 2007 Yanmar Marine International
TROUBLESHOOTING
Corrective action
Lap the valve seat or replace
the valve(s).
Adjust the valve clearance.
Replace the head gasket.
Disassemble, check and
measure the dimension. If
wear is found, replace the
cylinder block.
Disassemble, check and
measure the dimension. If
wear is found, replace.
sticking is found, clean or
replace.
Torque to specifications.
If damaged, replace.
Check the terminal. Repair.
Remove and check the air
heater. Replace if necessary.
Check operation of the relay.
Replace if necessary.
Replace.
Check. Replace if necessary. See Air Heater on
Remarks
See Inspecting the Cylinder
Block and Components on
page 5-22.
See Inspecting Intake /
Exhaust Valves and Valve
Guides on page 5-30.
See Cylinder Head
Components and Functions
on page 5-26.
See Inspecting the Cylinder
Block and Components on
page 5-22.
See Replacing the Piston
Rings on page 5-39.
See Replacing the Piston
Rings on page 5-39.
See Cylinder Head
Components and Functions
on page 5-26.
See Checking the Valve
Springs on page 5-32.
See Troubleshooting Fuses,
Relays and Harnesses on
page 13-21.
See Air Heater on
page 13-81.
See Air Heater on
page 13-81.
See Troubleshooting Fuses,
Relays and Harnesses on
page 13-21.
page 13-81.
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