To provide a hot-bulb diesel engine of further high thermal efficiency by using water and fuel.

A hot-bulb diesel engine system is characterized by including, a monitor device monitoring piston position in the diesel engine and generating pulse signal corresponding to the piston position, a water injector supplying water to the hot-bulb diesel engine based on the pulse signal of the monitor device, a water force feed means supplying water to the water injector, and the hot-bulb diesel engine including a cylindrical cylinder having a scavenging passage and an exhaust passage formed, a high temperature combustion chamber provided vertically above the cylinder and including a fuel nozzle supplying fuel, an air chamber provided vertically below the cylinder, a piston slidably arranged in the cylinder, a flywheel rotatably arranged in the air chamber, and a rod connecting the flywheel and the piston and converting rotary motion of the flywheel and sliding motion of an inside of the cylinder.