Overheating at idle

[JayRich]

I can run at cruise speed all day with no issue, but sometimes when idling through the no wake zone, my starboard engine will get hot, or at least trigger the temp light. Where should I start?
2008 Yamaha 232 Limited.

 

[Acard7]

I’d start by giving it a good flush through the flushing ports. Turning on: engine on, water on. Turning off: water off, engine off. Next I’d pull your pumps and just check your screens on the intake to the cooling system. After that I’m not sure!

 

[Dixemon]

Sounds like you have some restrictions in your cooling system. I would be pulling all my cooling hoses and inspecting for debris in all the orifices. You could also pull you thermostat and run the motor on the hose. See if you get anything to flush out.

 

[Cambo]

Do you have any marine growth wear you boat if you hit reverse it blows junk off the sea floor then your pump sucks it up and it could block the water pick up but then it blows out at speed.
Check your oil if it’s milky you could have a breach in your exhaust manifold.

 

[Babin Farms]

Salt water or fresh?? Are your pissers working?? Even at low speeds? I tend to look over the side of the boat every few minutes to make sure they're working properly. If they aren't spitting water out then that will tell you that there's an issue.

 

[Scottintexas]

Glad to have you on board,

you should start by watching this video if you haven't already,

how long have you owned you boat ?
when did the overheating start ?

in the video, buck shows where his 2008 boat had internal flashing material left in some of the plastic fittings that was causing his overheating,

I'd probably pull the thermostat to try to judge the condition of the internals, post a picture of it for us,

.

 

[Murf'n'surf]

Faulty thermostat not opening all of the way. When boat is underway there's enough force to pass through. That's just one of the many possibilities but simple to check.

 

[JayRich]

Glad to have you on board,

you should start by watching this video if you haven't already,

how long have you owned you boat ?
when did the overheating start ?

in the video, buck shows where his 2008 boat had internal flashing material left in some of the plastic fittings that was causing his overheating,

I'd probably pull the thermostat to try to judge the condition of the internals, post a picture of it for us,

.

I’ve had it 3 years, fresh water only. Had this problem once end of season last year but I found an obstruction (stick) in the pump. Had same problem first time out this year, again, had picked up a stick on the pump. Cleared it and no more problems until Sunday just before we came in off the lake, this time I couldn’t find anything in the pump.

 

[JayRich]

Salt water or fresh?? Are your pissers working?? Even at low speeds? I tend to look over the side of the boat every few minutes to make sure they're working properly. If they aren't spitting water out then that will tell you that there's an issue.

Fresh water. Have never gotten much from pisser of either engine at idle but never had an issue with overheating.

 

[Babin Farms]

Fresh water. Have never gotten much from pisser of either engine at idle but never had an issue with overheating.

At idle you wont have much if any but what does it do while your cruising? Spit out a good stream or is it just dribbling out?

 

[JayRich]

At idle you wont have much if any but what does it do while your cruising? Spit out a good stream or is it just dribbling out?

Squirts out pretty good at speed.

 

[Cambo]

When you picked up the stick did you get an engine over heat light? If so did you run the boat long. Thats what took out my friends MR1 exhaust manifold what happened was the aerated water did not cool properly and and the exhaust gases melted a small hole allowing hot exhaust gasses into the cooling jackets especially at idle creating an overheat only at idle. Eventually the hole grew and allowed a small amount of water into the combustion chamber that weeped past the rings causing the milky oil.

back to my original questions

did you check the oil?

or do you use reverse in shallow water when taking off in your boat that is the easiest way to suck up junk and clog the cooling

 

[JayRich]

When you picked up the stick did you get an engine over heat light? If so did you run the boat long. Thats what took out my friends MR1 exhaust manifold what happened was the aerated water did not cool properly and and the exhaust gases melted a small hole allowing hot exhaust gasses into the cooling jackets especially at idle creating an overheat only at idle. Eventually the hole grew and allowed a small amount of water into the combustion chamber that weeped past the rings causing the milky oil.

back to my original questions

did you check the oil?

or do you use reverse in shallow water when taking off in your boat that is the easiest way to suck up junk and clog the cooling

I don’t think it ran long, I shut it off as soon as I saw the light. I haven’t been back to my boat to check the oil yet. I launch from a dock and lift in about 13’ of water.