What does the term “Wet Stacking” mean in a diesel engine?
A. Diesel engines are designed to operate with a load. When a diesel engine operates considerably below the rated output level the engine can start to over-fuel or “Wet Stack”. Diesel engines perform most efficiently in the 70-80% range of rated output. When an engine operates for a prolonged period of time below 40% of the rated output it begins to over-fuel. This is similar to driving a car in the City at slow speeds for long periods. Wet Stacking occurs because the injection tips began to carbonize and disrupt the fuel spray pattern. Commercial generator systems often have widely varying loads with some low output conditions often have wet stacking problems because of the diverse load applications and owners artificially load the generator with an automatic load bank. A load bank will place a “false” load on the generator system to keep the diesel engine properly loaded. Once a diesel engine begins to “wet stack” the only way to correct the problem is to load the engine for a couple
