Hobart 60PL20 Operation And Maintenance Manual page 177

OM-2053
Wet-Stacking in Generator Set Diesel Engines
All diesel engines operated for extended periods under light load may develop a
condition commonly referred to as wet-stacking. This condition results from the
accumulation of unburned fuel in the exhaust system. It is recognizable by fuel
oil wetness around the exhaust manifold, pipes, and muffler. Liquid fuel, in the
form of droplets, may be spewed from the exhaust outlet.
Wet-stacking is common, and may be expected in diesel engines operated under
light load. Light loads do not allow the engine to reach most efficient operating
temperature for complete combustion of fuel. The unburned fuel collects in the
exhaust system to create the wet condition known as wet-stacking.
To alleviate wet-stacking in lightly loaded engines, it is recommended that the ma-
chine be connected to a load bank after each 200 hours of use and operated un-
der full rated load for one hour. This will burn away and evaporate the
accumulation of fuel in the exhaust system. This clean-out procedure should be
considered as a regular maintenance operation for machines operated under
light load. The time schedule of 200 hours may be changed as required to suit
each user's particular needs and operating conditions.
December 31/91 Revised Wetstacking
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