Recently purchased a Scout boat with a 1996 70hp Evinrude. Appearently the previous owner had an impeller bust apart and instead of paying for the job to be done correctly, he just slapped a new impeller in and sold it. Yes everything worked when I bought it but I guess peices of the old impeller were still in the cooling jacket. So the motor overheated and I'm im the process of trying to clean things up. Question is how can I flush out and be relativly positive that all the small pieces are out of the motor???