Service manual

G420F(FE) Service Manual Chapter 3. Engine Mechanical System 41
Troubleshooting
Symptom Possible cause Remedy
Low compression
Cylinder head gasket damaged
Worn or damaged piston ring
Worn piston or cylinder
Worn or damaged valve seat
Replace gasket
Replace ring
Repair or replace piston and cylinder block
Repair or replace valve and seat ring
Low oil pressure
Insufficient engine oil
Oil pressure switch defective
Oil filter clogged
Worn oil pump gear or cover
Thin or diluted engine oil
Oil relief valve clogged(Open)
Excessive bearing clearance
Check engine oil level
Replace oil pressure switch
Install new filter
Replace
Replace engine oil
Replace or inspect
Replace bearing
High oil pressure Oil relief valve clogged(Closed) Repair relief valve
Noisy valve
Thin or diluted engine oil
Faulty HLA
Worn belt stem or valve guide
Replace engine oil
Replace HLA
Replace belt stem or valve guide
Noisy connecting rod
or timing belt
Insufficient engine oil
Low oil pressure
Thin or diluted engine oil
Excessive bearing clearance
Check engine oil level
Refer to too low oil pressure
Replace engine oil
Replace bearing
Noisy timing belt Incorrect belt tension Correct belt tension
Low coolant level
Coolant leak from
Heater or radiator hose
Defective radiator cap
Thermostat housing
Radiator
Water pump
Repair or replace parts
Retighten clamp or replace
Replace gasket or housing
Replace
Replace parts
Radiator clogged Foreign material into coolant Replace coolant
Abnormally high
coolant temperature
Thermostat defective
Radiator cap defective
Abnormal flow in cooling system
Loose or missing driving belt
Loose water pump
Water temperature wiring defective Cooling pan
defective
Radiator or thermostat switch defective
Inefficient coolant
Replace parts
Replace parts
Clean or replace parts
Correct or replace
Replace
Repair or replace
Repair or replace
Replace
Add coolant
Abnormally low coolant
temperature
Thermostat defective
Water wiring defective
Replace
Repair or replace
Oil cooling system leak
Loose connecting part
Cracked or damaged hose, pipe, and oil cooler
Retighten Replace
Exhaust gas leak
Loose connecting part
Pipe or muffler damaged
Retighten
Repair or replace
Abnormal noise
Breakaway exhaust plate in muffler
Rubber hanger damaged
Pipe or muffler with body Interfered
Pipe or muffler damaged
Catalytic converter damaged
Each connecting gasket damaged
Replace
Replace
Repair
Repair or replace
Replace
Replace