temperature egr cooler 58 has similarly configured passages to provide heat exchange flow as illustrated the charge air cooler 32 and low temperature egr cooler 58 are contiguous with the charger cooler 32 being higher than the low temperature egr cooler 58 a valve 82 interconnects the inlet end 74 of charge air cooler 32 to the inlet end 78 of low temperature egr cooler 58 the inlet end 74 is upstream of the internal passages in charge air cooler 32 and is thus upstream of charge air cooler and is exposed to the pressures and temperatures from the outlet of the compressor 28 valve 82 operates on a pressure differential so that higher pressure in inlet end 74 than inlet 78 causes gas flow from a point upstream of the charge air cooler through the low temperature egr cooler 58 as illustrated valve 82 is a check valve only permitting flow from end 74 to end 78 so that any moisture generated within the low temperature egr cooler 58 would not pass to the charge air cooler 32 valve 82 permits a flow of air from a point upstream of the charge air cooler through the low temperature egr cooler to purge it of any accumulated moisture the air upstream of the charger cooler 32 is at a high.