Abstract: For exhaust gas recirculation in internal combustion engines operating, for example, with low sulphur marine diesel oil, an exhaust gas cooler with a cooling unit may be applied that uses a liquid injection system to maintain clean and/or clean a cooling surface of the cooling unit. The liquid injection system may provide liquid into an exhaust gas passage upstream of and or along a condensation starting region the cooling surface, thereby reducing the formation of films and deposits from particulate matter and condensing liquid of an evaporated liquid within the exhaust gas such as sulphuric acid and/or water, as those deposits could otherwise at least partially block the exhaust gas cooler.