When automotive heat exchangers such as radiators and condensers are manufactured, serious erosion caused by the molten filler metal from the header occasionally occurs on the tubes during brazing. In our previous study, we proposed a novel experimental method which consisted of using a feeder and a base plate on a gutter made for the flow of molten filler, and we quantitatively evaluated the relationship between the volume of flowing molten filler and the level of erosion. We used Al–12%Si molten filler to investigate the effect of chemical composition, in particular, the Si content of the base plane, on the level of erosion. When Al–0–1.2%Si alloys that have a solidus temperature that is higher that their brazing temperature were used, the level was almost constant irrespective of the Si content of the base metal. However, when Al–0–2.0%Si alloys that have a solidus temperature that is lower than their brazing one are used, the level increases.