EGR cooler and engine failures on the 6.0L Power Stroke can often
be traced to a chain reaction that starts with the Engine Oil Cooler
failure. The engine oil cooler has small narrow, flat cooling tubes that are
easily clogged by foreign material in the coolant. Engine coolant flows through
the engine oil cooler first and then to the EGR cooler. So if the engine oil
cooler becomes clogged, then engine oil may become overheated causing poor performance
and eventually engine damage. The restricted downstream flow of coolant will
also cause coolant within the EGR cooler to flash-boil and spill coolant into
the overflow tank. Eventually the overflow tank overfills, coolant is lost and
the engine will overheat. In time, the EGR
Cooler can also become corroded under these conditions, and will leak coolant
into the engine oil.