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Overheat issue

Hollywood

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Location
Meridian MS
Boat Make
Yamaha
Year
2006
Boat Model
SX
Boat Length
23
Hey guys, 2006 yam 230sx. Port overheat light comes on when at full throttle for approx 1 min. Cut engines off , swim under the boat check the water intakes , nothing, check the clean out ports , nothing. Start back up and the light is off and can motor around again but when I get full throttle again for approx one min it does it again.

Any ideas ?????
 

Port0222

Jetboaters Lieutenant
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Orono, MN
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Yamaha
Year
2006
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AR
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23
Hey guys, 2006 yam 230sx. Port overheat light comes on when at full throttle for approx 1 min. Cut engines off , swim under the boat check the water intakes , nothing, check the clean out ports , nothing. Start back up and the light is off and can motor around again but when I get full throttle again for approx one min it does it again.

Any ideas ?????
Hey Hollywood, welcome to the site.

You may have some cavitation at full throttle -- meaning it is spinning air instead of water.

What rpms are you at when at full throttle. Do both motors match?

Is water coming out of the side pee holes? At Medium rpm (7000?), and maximum rpms?

There is a small white screen inside your jet pumps that is the entrance to the cooling system. That could be clogged as well.

Can you run at 8000 rpms all day with no issue, it is only an issue at full throttle?
 

Hollywood

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Meridian MS
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Yamaha
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2006
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23
Thanks for the reply Port, full throttle is a tad over 10k rpms. Yes water comes out both holes on the side when at normal cruising speeds . Yes both engines match on rpms no matter what speed . Didn't look to see if water came out the sides holes at full throttle.

How do I check the white screen ?
How do I fix a cavitation problem ?
 

Hollywood

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I have had prob 15 boats in the past 20-25 years and a few jet skis but this is my first jet boat so yeah I'm new to these type issues.
 

Port0222

Jetboaters Lieutenant
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Yamaha
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2006
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AR
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Both of those issues would likely require you to pull the jet pump. Not overly complicated and the instructions are in the FAQ. The screen is adjacent to the impeller.

Cavitation will look like a bacteria is eating your impeller, but you should be able to hear that and have a slight loss of power. You may be able to see some cavitation if you put the throttle to forward, and shine a flashlight into your jet pump.

Cavitation would be caused by any blemishes or imperfection in your impeller (like a rock chip)

There is a video on YouTube that explains our cooling systems pretty accurately. If you do not want to pull the jets, you can also start with that video. I believe he states that he had a cooling issue and explains the reason that caused it.

Google mr-1 cooling system, you should be able to find it.
 

Hollywood

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Awesome, thank you very much for your time !!!
 

Hollywood

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2006
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Have another ? For you. Should the throttle be a bit tough or should it be very smooth and easy to work ? Most boats I have had were pretty smooth , have had a couple that were a little hard to push but this dual throttle seems a little tougher than it should be
 

Scottintexas

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are you going over waves when it cuts out?
also, you could also have an exhaust leak and the air mixture is shutting the engine down, try running with the hatch open to see if you can duplicate the problem,

you really need a YDS, are any of your dummy lights blinking under your tach? I doubt that an overheat is going to shut down within a minute of you going to 10k rpm

can you run at 8K rpm with no problems?

The throttles should be snug but smooth, it's not uncommon for them to go bad and bind, especially on your age of boat,
 

Hollywood

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Meridian MS
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Yamaha
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It didnt shut itself down I shut it down when I saw the temp light come on . But yes I can run at 8-9 K and it doesn't happen , only when I'm at full throttle 10-10.2 k approx .

What can I do to make the throttles a little more smooth ?

Also needing the 2 glove box seals if u know where I can get those , both glove boxes flood when it rains.
 

Scottintexas

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check the FAQ for tips about changing the cables, I would disconnect them first at the engines/buckets to help pin point it is the cables

I would take a infrared thermometer out next time and see if you can't identify where the overheat is happening, on the cylinder or exhaust

How long have you owned your boat? do you know anything about it's history or salt water use,

one member had his exhaust ports fill with sediment and it would cause an intermittent problem, in this area,
exhuast.jpg
 

Hollywood

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Location
Meridian MS
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Yamaha
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2006
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SX
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23
It was mainly in salt water before I got it , I bought it from the original buyer (one owner).

Thanks for the help . I'll deff use a laser thermometer and check it Saturday when I'm out.
 

QCI Sean

Active Member
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Hollywood, did you get this figured out? I’m going through the exact same thing. I have a 2008 AR230 that has its left motor that will overheat only writhin 200/300 rpms of WOT. I’m thinking there is some type of cooling system blockage, but was curious what you had found your problem to be.

Thanks!!
 

Jgorm

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You could try adding a bottle of vinegar to the cooling feed and let it sit overnight. Flush out and run weed eater wire through all the cooling tubes. If the boat has been a salt water boat is whole life you might have substantial corrosion on the engine and exhaust.
 
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