Question for the motor experts...  2016 25HP Merc Tiller (4 cycle), probably about 40-50 hours on it.  I took it in for maintenance at the end of Feb, had it out 6-7 times this year with no issues.   Yesterday I ran it about 15 minutes, stopped for about 2 hours, and then ran it again when I encountered a problem.  Maybe 10-15 seconds after full throttle I felt something weird and sensed the engine dying, looked back and saw the red oil pressure light on solid.  I checked the obvious - oil level, fuel line, made sure the prop was still on etc...    Started it back up, had a good stream of water, no light, so I putted around for a few minutes and then slowly opened it up.    Ran the rest of the day without issue, including the end of the day where I close to the ramp and just did laps for about 20 minutes pretty full full throttle.  

 

Rewind a year ... I remember once last year when I was running full throttle and I trimmed the engine just a hair, and saw the red warning light turn on for maybe 1-2 seconds.   The engine ran fine, I wouldn't have noticed anything if I hadn't of seen the light.  I just assumed that maybe it was normal when you trim out like that, but someone I talked to said they don't have that happen.   Never happened again.

 

I am taking it to the Marina tonight, of course I worry about them saying it runs fine and then having the problem again.   

 

Any clues?  

Just an update in case someone else has same issue - 2017 Merc 25/30.   Problem was overheating, not oil pressure.   Mercury said they have had problems with this year/model with thermostat sticking, so the remedy is to replace it.