F250s on a 300 marlin 2006 Temperture

offshore

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I have the square yamaha gauges and the engine temp when running goes one notch past the middle towards the hot. Is this normal or is it a problem waiting to happen. I just changed the pumps 150hrs ago.Thx
 
Well, if you engines used to display a lower temperature on the gauge, it's not normal. I would check the water pressure and the thermostats.

My F250 runs less than half way across the temperature range even with 90 degree surface temperatures in the GOM. But I often pick up weeds and the temp will move well above the halfway mark. After blowing the weeds off with few seconds in reverse, the temp returns to normal.
 
Thx, but both engines seem to do it almost at the same time. Once I bring the boat down to trolling speed the temp goes right back to normal.
 
Re: F250s on a 300 marlin 2006 Temperature

Have you run the engines through sand or mud recently? You could have clogged up water passages.

If the water pump and thermostats are OK, the only other possibilities are the poppet valves and water passage obstructions.

A water pressure gauge is an invaluable tool for trouble shooting overheating problems in outboard engines.
 
no mud or sand i havent had any alarms so far and i flush my engines after each use thx for the response.
 
I have experienced the same results. If I remember correctly, both of my temperature gauges sit at or one bar to the left of the middle most of the time I am operating the boat. When I run the boat hard (4500rpm or above) in warm water I have seen both bar gauges go one bar to the right of ceneter. Like you when I slow down they go back to the middle of the operating range.

Hope this helps.
 
I remember on my Single F250, anytime I got above 4500RPMs for cruising the temp bar would increase, back off alittle and it would steady out.

Sounds like standard operating to me.
 
sounds like the water pump or the water passage ways are a little undersized, poor engineering if so?
I wonder if the 300's and 350's have the same read at cruising RPM.
 
You don't say wether or not the pump housing and seals were changed. I had a similar problem and did the complete pump change myself. The problem went away.