Problem with heat alarm with 300 HPDI Help?

[Terry L Flohr]

I have a 2006 300 HPDI Yamaha engine with a heat alarm problem. Been in shop and they cannot figure out how to fix Problem: While fishing after low speed idle and adjusting drift speed the heat alarm will go off. I have replaced both thermostats, changed both water separators and had a new water pump installed. The problem still is there. Any ideas what the problem is and how to advise my dealer to proceed?

Terry Flohr (TFlohr@verizon.net)

[ausnoelm]

maybe check the poppit/bypass valve to make sure it is functioning correctly.