Flux Residue and Migration in Charge Air-Cooled Engines

Traditionally, most charge air coolers (CACs) have been constructed using the Nocolok aluminum brazing process. The Nocolok process uses flux, some of which remains after the manufacturing process, and migrates through the intake tract to the engine during normal use. This migration and deposition on engine components can cause a variety of issues with engine operation. Currently the only alternative to Nocolok brazed CACs for engines sensitive to flux migration is vacuum brazing, which comes at a significant price increase. In the effort to reduce cost and increase efficiency, there is interest in whether a Nocolok brazed CAC with a reduced amount of flux residue can be successfully applied to flux-sensitive engines. This paper compares the impacts of Nocolok flux migration on engine hardware between a traditional Nocolok brazed CAC versus a Nocolok brazed CAC with a reduced amount of flux residue using a simulated vehicle operation test and its analysis, and examines whether a CAC with reduced flux residue can potentially be used in a flux-sensitive application.