Would like to share one recent indecent which happened on one of our diesel generators. In a while after engine start up we have noticed a high exhaust gas temperature on one of cylinders and black smoke began to appear from exhaust funnel. The engine was immediately stopped and fuel injector inspected. The injector nozzle was cut off and fuel was literally pumped to the cylinder unrestricted. Moreover, a lot of fuel managed to get into the engine crankcase. The oil had to be replaced. What could have served the nozzle defect? Low-temperature corrosion is one of possible things. The engine runs on diesel fuel, the injectors do not have additional cooling. A week before the accident, an cooling water electric heater broke down. In 24h the heater was back into operational state. Perhaps heater breakdown contributed to the corrosion of the fuel injector nozzle due to carbon deposits on it. No corrosion/pitting marks were found on the other nozzles.