2006 Mercury 50HP Two-Stroke Overheat alarm

[hatfieldm]

I have a 2006 Mercury 50 HP two stroke outboard that is has an overheating alarm that just started today. It only alarms at speed. The telltale water seems normal and is stronger at speed like I would expect.

I opened the cowling on the motor and there was a plastic box with ventilation ducts that had fallen off of the front of the motor. I re-attached this and was sure it was the problem, but it still overheats.

Thanks in advance for any help.

[alaskanassassin]

Poppit valve may be the issue if it only happens at speed. Maybe a partial blockage in your cooling passages that only is an issue at high rpm's.