TROUBLESHOOTING
Troubleshooting by Symptom
12/05
6LY3 Service Manual
13-11
© 2007 Yanmar Marine International
The starting motor rotates, but the engine will not start. (continued)
Low compression.
Compressed air leakage
from intake / exhaust valves.
Lap the valve seat or replace
the valve(s).
See Inspecting the Cylinder
Block and Components on
page 5-22
.
No clearance of intake /
exhaust valve.
Adjust the valve clearance.
See Inspecting Intake /
Exhaust Valves and Valve
Guides on page 5-30
.
Faulty cylinder head gasket. Replace the head gasket.
See Cylinder Head
Components and Functions
on page 5-26
.
Wear on the top of the
cylinder.
Disassemble, check and
measure the dimension. If
wear is found, replace the
cylinder block.
See Inspecting the Cylinder
Block and Components on
page 5-22
.
Piston ring wear.
Disassemble, check and
measure the dimension. If
wear is found, replace.
See Replacing the Piston
Rings on page 5-39
.
Sticking of the piston ring(s). Disassemble and check. If
sticking is found, clean or
replace.
See Replacing the Piston
Rings on page 5-39
.
Loose cylinder head bolts.
Torque to specifications.
See Cylinder Head
Components and Functions
on page 5-26
.
Damaged valve spring.
If damaged, replace.
See Checking the Valve
Springs on page 5-32
.
Air heater does not operate. Air heater terminal is
disconnected, loose or has
failed.
Check the terminal. Repair.
See Troubleshooting Fuses,
Relays and Harnesses on
page 13-21
.
Air heater relay terminal is
disconnected, loosened or
has failed.
Faulty air heater.
Remove and check the air
heater. Replace if necessary.
See Air Heater on
page 13-81
.
Faulty air heater relay.
Check operation of the relay.
Replace if necessary.
See Air Heater on
page 13-81
.
Fuse burned out.
(Air heater “A” or “B”: 250A)
Replace.
See Troubleshooting Fuses,
Relays and Harnesses on
page 13-21
.
Clogged intake / exhaust
lines.
Check. Replace if necessary.
See Air Heater on
page 13-81
.
Trouble symptom
Causes
Corrective action
Remarks