Cold corrosion is an abnormal corrosion accompanied by a drop in engine temperature, which allows acid to build up on the cylinder liner. Exhaust systems suffer from cold corrosion due to acid formation from combustion process of the engine. It produces sulfuric acid which leads to excessive liner wear, requiring expensive replacement. Cold corrosion is not only serious in the latest engine designs but also it has impacts on earlier engine designs modified for part-load or low-load operation. The design modifications included: Variable turbo charger nozzle rings fitted Engine tuning changes Turbocharger cut-out Exhaust gas bypass valve fitted