Honda BF25 overheating

Pthorburn

Recruit
Joined
Mar 28, 2017
Messages
3
My BF25a is overheating around the exhaust. The thermostat is new and functioning properly and the water pump has been rebuilt and pisses strong and cool. Any ideas on what would be causing the overheating in this region of my outboard would be greatly appreciated.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Welcome to Iboats,

If overheating means that exiting water through prop is warm/hot when at idle as not to burn your hand, it's normal. Will be much hotter when giving more throttle which is still normal..It's heated water coming down from powerhead through the prop.

Happy Boating
 

Pthorburn

Recruit
Joined
Mar 28, 2017
Messages
3
Welcome to Iboats,

If overheating means that exiting water through prop is warm/hot when at idle as not to burn your hand, it's normal. Will be much hotter when giving more throttle which is still normal..It's heated water coming down from powerhead through the prop.

Happy Boating

​It is causing an alarm to sound when I am in gear and go above anything more than no wake rpms.The unit around the exhaust literally becomes too hot to touch for more than a few seconds.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
If OB is tested on a stand with muffs while ON, would you say that water coming out prop is that hot as lower leg exterior ? The alarm could be due to a bad heat sensor failing. How old is that OB, is fresh or salt water used ?

Happy Boating
 

Pthorburn

Recruit
Joined
Mar 28, 2017
Messages
3
If OB is tested on a stand with muffs while ON, would you say that water coming out prop is that hot as lower leg exterior ? The alarm could be due to a bad heat sensor failing. How old is that OB, is fresh or salt water used ?

Happy Boating

​The water coming out of the prop is of normal temperature. I just discovered that some water runs out of where my oil drain plug is. The water that drips out of around the oil drain plug in the midsection is very hot. 2006 ran only in saltwater.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
The water that drips out around midsection is from a small hole next to oil drain ? if so, it's a drain hole, is it diam restricted ? One issue that occurs to me for the heat alarm triggering prematurely if sensor is not shot, could be that internal OB water paths are so darn salt restricted that heat temp sensors senses a higher water temp passing by and triggers itself.

How well was/is that 11 year oldie OB correctly flushed with fresh water right after use on salt water ? Never flushed, barrel, muffs flush ? Bought new, second hand ?

Happy Boating
 
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