Exhaust Color
Problem / Symptom
Cause
Action
White Smoke
Cold engine
Allow engine to warm to operating
temperature
See your authorized Yanmar deal-
er or distributor
Incorrect fuel
Replace fuel with correct type
Defective (leaking) fuel injector
See your authorized Yanmar deal-
er or distributor
Injection timing is incorrect
White Smoke with Water Vapor
Leaking cylinder head gasket
See your authorized Yanmar deal-
er or distributor
Leaking charge air cooler
Cracked cylinder head
Cracked cylinder
Blue Smoke
Worn piston rings / cylinders
See your authorized Yanmar deal-
er or distributor
Oil leak in turbocharger (oil
present in intake manifold)
Damaged piston cooling nozzles
Black Smoke Under Load
Clogged intake air filter
Replace or clean as necessary
Incorrect valve timing
See your authorized Yanmar deal-
er or distributor
Defective (leaking) fuel injector
Low charge air pressure
Clean or replace clogged air filter
See your authorized Yanmar deal-
er or distributor
Excessive exhaust back pressure
See your authorized Yanmar deal-
er or distributor
Plugged intake port(s)
See your authorized Yanmar deal-
er or distributor
Vibration - Drive Disengaged
Problem / Symptom
Cause
Action
Rough at All Engine Speeds
Air in fuel system
Bleed fuel system
Faulty fuel injector
See your authorized Yanmar deal-
er or distributor
Leaking cylinder head gasket
Damaged intake or exhaust valves
Incorrect injection pressure
TROUBLESHOOTING
BY Series Operation Manual
61
© 2008 Yanmar Marine International