Include

[dswift]

Causes: A diesel engine, like all internal combustion engines, to operate at maximum efficiency has to have exactly the right
air to fuel ratio and be able to sustain the operational temperature it was designed to run at for a complete burn of
the fuel. When a diesel engine is operated on light loads it will not attain its correct operating temperature.
When the diesel engine is allowed to run for extended periods below its designed operating temperature, unburned
fuel is exhausted and noticed as wetness in the exhaust system, hence the phrase “W
et Stacking.”
Engine Effect: When unburned fuel is exhausted out of the combustion chamber it starts to build up in the exhaust side of the
engine resulting in fouled injectors and a build up of carbon on the exhaust valves, turbo charger and exhaust.
An excessive amount of deposits can result in a loss of engine performance as gases bypass valve seatings,
exhaust buildup produces back pressure and deposits on the turbo blades reduces turbo ef
ficiency. Over short
periods permanent damage will not be incurred, but over longer periods damage will occur as deposits scar
and erode key engine surfaces. (see diagram one)
Another result of running below the designed operational temperature is the pistons rings, fitted to the
piston to allow expansion of the piston as the engine temperature rises, do not attain their level of designed
tightness required to adequately seal the space between the cylinder walls. This results in unburned fuel and gases
escaping into the oil pan and diluting the lubricating properties of the oil, leading to premature engine wear
.
Why Avoid: Having discussed the effect of “Wet Stacking” on the diesel engine, the reasons for avoiding the condition are now known, but in addition to the adverse engine effect the designer and user of a system have to consider:
Expense: Excessive “Wet Stacking” will shorten engine life by many years and before planned replacement.
Pollution: Many urban areas are restricting the level of smoke emissions “Wet Stacking” produces.
Power: Even before an engine is damaged deposits will reduce maximum power. A prematurely worn
engine will have a lower maximum power than it was designed to develop.
Maintenance: An engine experiencing the effects of “Wet Stacking” will require considerable more maintenance
than an engine that is adequately loaded.