Abstract: Disclosed herein are methods for detecting a water leak in a locomotive engine cooling system comprising numerous components, each being a potential source of leakage of water. The method typically comprises performing at least one inspection providing an indication of a water leak from an engine cooling system of the locomotive. The step of performing at least one inspection may comprise at least one of several steps including performing a visual inspection to determine if water is leaking from a portion of the cooling system external to the engine; performing a visual inspection of exhaust of the engine to detect an indication of water vapor in the exhaust; performing a visual inspection to detect an indication of water leaking into an intake air manifold 30 of the engine; performing an engine oil analysis to detect water in the engine lubricant; reviewing a fault log history for the locomotive; and checking a level of a cooling system sight glass.