Patent ID: 7461637

Claim:
A diesel engine comprising: a fuel supply passage via which fuel is supplied from a fuel tank to an oil pan through a supply pump; a lubrication-system fuel supply passage via which fuel is supplied from the oil pan to engine parts to be lubricated through a lubricating oil pump; an injection-system fuel supply passage via which fuel is supplied from the oil pan to an injection system through an injection pump, a lubrication-system fuel return passage via which return fuel from the engine parts is returned to the oil pan; and an injection-system fuel return passage via which return fuel from the injection system is returned to the fuel tank, wherein the injection-system fuel supply passage includes a three-way valve having an adjustable degree of opening, and a fuel pipe for a supply of fuel from the fuel tank is connected to the three-way valve, wherein the adjustable degree of opening of three-way valve depends on the temperature of fuel.