Abstract: A combustion engine system (10) includes a combustion engine (11), a coolant system (46), an exhaust gas recirculation loop (32), and an exhaust gas cooler (34) connected in the loop (32) to transfer heat from the recirculating exhaust gas flow to a coolant flow supplied by the coolant system (46). The exhaust gas cooler (34) includes a plurality of coolant flow passages (66) interleaved with a plurality of recirculating exhaust gas flow passages (68), with the flow passages (66,68) being defined by a stack (60) of nested plates (62,64). Each of the plates (62,64) includes a peripheral flange (72,74) that is nested with the peripheral flange (72,74) of any adjacent nested plate (62,64) to enclose the flow passages (66,68).