PRT EMCT OVRHT alarm

[tricountytrail]

So question when I get PRT EMCT OVRHT alarm. Can I see the value of the sensor on the Port Exhaust coolant temperature or is it just a open close switch set at 212F?
I know my sea pump housing is scored up and is probably cavitating at cruise speed.
I just changed out the Port Sea pump but haven't got a chance to take it out yet.
Attached is the error before pump change, and pic of gage when running as alarm went off. Port engine coolant temp would creep up after 5-10 minutes and alarm PRT EMCT OVRHT would trigger.

 

[dubs283]

I'm not sure if the ecm reads an actual temp value off the ex manifolds or of its a threshold switch. Never used diacom on a mercury ec engine so can't say to what it'll show you.

My guess is that because you are allowed to see engine coolant temp and sea pump pressure those two values plus an ex manifold overheat ought to point you in the right direction for diagnosis. Could be a cavitating sea water pump but is more likely a blockage either in a cooling hose/oil cooler or a blockage in the cooling water exit portion of the ex manifold.

Close to 1000 hours run time makes me think failing ex manifold