Engine overheat??

[FishReaper]

I was wondering if I could get some help figuring out a boat issue.
I have a 2004 Johnson 115 4stroke. Today I was heading up the tailrace when I got a warning buzzer that engine was hot. I let it idle so water pump could pump with no load on engine. Buzzer stopped but light stayed on. Had a little bit of smoke. Once I fired back up I went back up at 2000 rpm to see if I could get it to get hot again. I floated down and went back up increasing rpm by 500 each time. It never got hot again. It did this to me once early spring. I shut down and cleaned some gravel from the pee hole and haven't had an issue since till today. Anybody have any ideas what to look at?

 

[DirtyMike]

Did you change out the impeller as well?

 

[FishReaper]

Have not changed any parts at all

 

[red eyed devil]

most outboards have a flush port try that and make sure ur tell tale is open. Other than that thermostat or impeller

 

[DirtyMike]

I'm not expert but I know sand in that impeller will wear it down pretty fast. And if it's not getting water in to cool the motor, the impeller might be the issue. Someone else can chime in and make me look stupid.

 

[WormWiggler]

Did you check your pee hole today?

Jeez that sounds.. uh.. odd

 

[NDwalleyes]

If you run the river and have never changed your water pump, you need to get that done. They collect sand, the sand plugs things up and like DM said it will wear your impeller down. If you've never had the lower seals replaced I would have that done too. Water in the lower unit is bad. I would guess you looking at a couple hundred bucks to get both taken care of.

I am concerned about where the smoke was coming from however....

 

[FishReaper]

Outboard was peeing great all day. If it was impeller wouldn't it have done it again after initial cool down?
Red devil where would I find the flush port and what does it look like? I can fix heavy equipment but a outboard is like an alien planet

 

[red eyed devil]

The pee hole on a motor [tell tale] will let u know if ur water pump is working if it's not plugged use weed wacker line to clear it, hook up water ears to motor after thermostat warms up u should have water coming out propeller or exhaust hole half way up lower end.

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the flush port should b by the vent port on lower end above oil drain hole

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if u have water coming out of the tell tale it sound like a thermostat to me

 

[tikkalover]

I'm not expert but I know sand in that impeller will wear it down pretty fast. And if it's not getting water in to cool the motor, the impeller might be the issue. Someone else can chime in and make me look stupid.

Your wife says you can do this on your own!!! ;:;rofl :;:stirthepot :;:smokin :;:sorry

 

[espringers]

Do all boats have a thermostat? Is there such a thing as running too cool? If not, what's the point of a thermostat?

 

[NodakBuckeye]

Not sure if all outboards have a thermostat, some have 2. My thermostat went bad last year at Van hook. Water coming out the tell tale but the the thermostat was not opening to allow water to fully flow around and through the engine jacket (or whatever it is called, lol) to cool it. I changed the thermostat and replaced the impeller. The therm allows optimal entine temp matter water temp. So, yes too much cold water on a stuck open therm could cause sluggish engine performance.

Pretty easy change for both, esp if you pick up a shop manual and then hit you tube too. I think I spent 50 bucks and had the job done in about 3 hours and it was my first attempt.

 

[sl1000794]

From what I remember when I took a years worth of Outboard Engine Mechanics almost 40 years ago was that water pumps were designed to pump almost 3x as much water as was needed to cool the engine. The reason was to cover owners that would just "slightly" start the engine dry to make sure that it would start. As a result the water pump wouldn't perform up to spec but would still push sufficient water to cool the engine. When the water pump works to spec the volume of water thru the engine needs to be regulated to allow the engine temp to rise to it's design temp and allow it to run at optimum performance. The thermostat does that by monitering engine temps. A thermostat stuck open would make the engine run rich (choked and inefficient) and a thermostat stuck partially closed would/could make an engine run hot. I think (???) that overheated (aluminum) outboard engine blocks just expand (thus shrinking the cylinder bore) and seizing the piston and stopping the engine until it has had a chance to cool and return to the designed bore. I don't think that this happening once will do serious engine damage. Just get the problem fixed … water pump or thermostat repair.

 

[espringers]

So there is such a thing as running too cool. Interesting.

 

[johnr]

the joys of boat ownership.

I have gone through 2 engine failures, and both were in the $7000 range to fix, once warrantied, the second was mrs johnr hip pocket paid.

Every time I run my boat I get a worried feeling about every sound it makes, thinking this will be the 3 time...

I wish I liked to shore fish, as it sure would be easier.

 

[svnmag]

https://www.youtube.com/watch?v=WEUw1t8RcZ0

 

[MuskyManiac]

johnr, I know you have had problems with your Opti, but I think there was an issue with your HP/year class. My Opti has been bulletproof for me. Heat issue with my engine are either related to water pressure/impeller, thermostat, or poppet valve. I know you can damage an Opti running high RPM's if the engine is not hot enough. My thermostat opens around 138 degrees. Poppet valve will open around 2500 RPM's, bypassing the thermostat. The telltale lets me know water is running through the air compressor, but doesn't tell you much more.