Overcooling most commonly occurs when the coolant bypasses a defective water temperature regulator and flows directly to the radiator preventing the engine from reaching normal operating temperature. Your coolant system is a vital one – but typically the most neglected and least understood.

Is overcooling engine bad?

Overcooling causes poor fuel economy because engine temperature won't be high enough to burn the fuel efficiently. ... Fuel contains carbon. Ineffective burning of fuel causes carbon deposits to form in the engine and reduces engine life.

What problems could occur from engine overcooling?

An overcooled engine can suffer from the following :

The engine does not achieve full power. Increased cylinder wear. Lower thermal efficiency i.e. more consumption of fuel. The oil does not thin out properly and increases the amount of fluid friction loss.