Symptom
Check items
Cooling system parts malfunction
Poor heat transfer
Water pump malfunction
Worn or loose drive belt

Thermostat stuck closed

Damaged fins
Dust contamination or paper clogging
Physical damage
Clogged radiator cooling tube
Excess foreign material (rust, dirt, sand, etc.)
Reduced air flow
Cooling fan does not operate
Fan assembly

High resistance to fan rotation
Damaged fan blades
Damaged radiator shroud



Improper engine coolant mixture ratio



Poor engine coolant quality

Engine coolant density

Insufficient engine coolant
Engine coolant leakage
Cooling hose
Loose clamp
Cracked hose
Water pump
Poor sealing
Radiator cap
Loose
Poor sealing
Radiator
O-ring for damage, deterioration or improper fitting
Cracked radiator tank
Cracked radiator core
Reservoir tank
Cracked reservoir tank
Reservoir tank cap
Loose
Poor sealing
Overflowing reservoir tank
Exhaust gas leakage into cooling system
Cylinder head deterioration
Cylinder head gasket deterioration
Except cooling system parts malfunction

Overload on engine
Abusive driving
High engine rpm under no load
Driving in low gear for extended time
Driving at extremely high speed
Power train system malfunction

Installed improper size wheels and tires
Dragging brakes
Improper ignition timing
Blocked or restricted air flow
Blocked bumper


Blocked radiator grille
Installed car brassiere
Mud contamination or paper clogging
Blocked radiator

Blocked condenser
Blocked air flow
Installed large fog lamp