COOLANT LEAK FROM LOW TEMPERATURE COOLING CIRCUIT (N63R): This Service Information Bulletin (Revision 5) replaces SI B17 06 17 dated June 2019. Traces of coolant leaking from the expansion tank of the low temperature cooling system. Coolant in the low temperature cooling circuit may also have an acrid smell and discoloration (1). Aluminum corrosion in the charge air intercoolers or in the radiator for the low temperature cooling is causing an unfavorable chemical reaction to the coolant.