Yanmar 6BY2 - Engine Runs Cold; Coolant Loss; Helm Panel Display

TROUBLESHOOTING
Troubleshooting Chart
12/05
BY Service Manual
13-9
© 2009 Yanmar Marine International
Engine Runs Cold
Coolant Loss
Helm Panel Display
Problem / Symptom Cause Action
Instrument Shows Low Temperature
Defective sensor / instrument Repair as necessary
Defective thermostat Replace
Cabin heater / boiler too large Replace with smaller unit or remove
Problem / Symptom Cause Action
Repeated Low Coolant Level
Defective cylinder head gasket (external
leakage)
Replace
External leakage at connection Repair as necessary
Coolant Forced Out of Coolant Recovery
Tank
Turbocharging pressure enters cooling
system via leaking charge air cooler
Repair / replace as necessary
Defective cylinder head gasket (internal
leakage)
Replace
White Smoke when Engine is Hot
Indicates Water Vapor
Crack in cylinder head (not cracks
between valve seats)
Repair as necessary
Cracked cylinder wall Repair as necessary
Leaking cylinder head gasket Replace
Problem / Symptom Cause Action
No Display
Harness connector loose Repair as necessary
Defective diode V1 Replace