| 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