car overheating no leaks

If your car’s overheating with no puddle to confess, the drama’s likely inside the cooling system.

• Thermostat stuck shut (or installed backwards after a service).
• Radiator cap not holding pressure, so it boils early.
• Cooling fans not kicking in (blown fuse/relay/sensor or a dead fan motor).
• Clogged radiator or coolant passages from old or mixed coolant.
• Water pump impeller worn or slipping, so flow tanks at revs.
• Air trapped after a coolant change; needs a proper bleed with heater on.
• Head gasket pushing combustion gas into the coolant—no external leak, big heat.
• Inner hose lining collapsed, pinching shut when hot.

Start with a pressure test, cap test and thermostat; verify fan operation and scan for codes, then infrared the radiator for cold spots.

Still cooking? Do a chemical block test for exhaust gas in the coolant and you’ll have your culprit quicker than your mate can say “try a bigger radiator.”