We’ve talked about this before. I just don’t get it. What is the added value of this setup? Why is the existing impeller pump not sufficient for feeding cooling water? 95% of the Amels (I’m guessing) has this set up and seem to be fine with it. Unless you remove the impeller pump completely, it will still be a source of (shaft) leakage at some point. The only thing I can imagine is if you use the genset frequently at continuous high loads you may want to improve the flow. In all honesty I would then enlarge the heat exchanger as the mickey-mouse version that is standard part of the genset seems to leave quite some room for improvement.
Adding another pump seems just to complicate things.
Just my two cents,