If the cooling system is contaminated with oil, fat and other greasy deposits then simply make 100 ltr solution of cold wash with water by the proportion of 10 Ltr Coldwash in to 100 Ltrs water ( or depend on contamination of oil deposits on the surface, cold wash ratio can vary 5 10% in freshwater ). Then circulate emulsion ( prepared solution of the cold wash with water ) for 8 - 12 hrs. And if solution temperature can maintain 50 - 60 degree, then cleaning performance can be increased within a short period of time. Finally, drain all soiled cleaning liquid followed by fresh water until outcome water remains clear.
Cleaning of the cooling system becomes compulsory when system required DESCALING, removal of scale deposits. As oily surface doesn't allow descaler to react with lime deposits.