Overheating warning starboard engine - tried most options already!

[Rogandanny]

The boat we’re talking about here is a brand new SX210, 13.5 hours on both engines. So a few weeks ago I got stuck on a sand bar and instinctively jammed the boat into reverse. The jets definitely sucked up a good amount of sand / mud, and the starboard engine threw an overheat warning. It limited RPMs to 3000, and I shut off boat engines. 20 min later they started up fine and I slowly went back into shore. Flushed engines well and stored in dry storage for 2 weeks while on vacation.

Yesterday, after the boat had been stored for 2 weeks, I flushed engines again and then put her in. She ran fine until I hit 6k RPM or so for 60 seconds then the starboard engine temp light came on again. Shut it off and brought it in with 1 motor.

What I have tried!
- flushing for up to 20 minutes - no overheat
- checked water intake screen - nothing blocking
- oil levels good

Could it be a faulty temp sensor? It’s a brand new boat... anything helps thanks.

 

[Jgonzalez114]

Good morning. I'm in the same boat with a 2008 AR210. My port engine has overheated twice last weekend. I'm going to take the thermostats off on both and make sure they are clean. I'm thinking about replacing them as well with a colder opening one. The thermostat for my engines are around $80 each but found the same looking Yamaha thermostat that opens at 50C versus 60C (original) for 1/4th the cost. I was also told on FB to check the temperature sensor so I'm thinking of doing that as well. I'm not one to just replace everything but I don't have the time to diagnose.

If I were you I would start with making sure the thermostat is clean as I've seen some pictures of ones with weeds stuck in them restricting flow.

Has anyone tried using the 50C thermostat part number 6E5-12411-30-00. Looks exactly the same as the 6D3-12411-00-00. Would anyone think there would be an issue using the colder opening thermostat since we don't have radiators and are pulling in fresh water anyway. I know the thermostat is to allow the engine to heat up to operating temperature but since mine is high hours I'm thinking everything should be properly seated already and should not cause any more wear.

 

[Babin Farms]

https://jetboaters.net/threads/how-can-we-prevent-diagnose-and-eliminate-overheating-problems.27469/#post-457198

Flushing the engines may not be able to build enough pressure to evacuate all of the sand. If it were me I would put it in the water and run it hard to try to "blow" all of the debris out. Higher RPM's, higher cooling system pressures.

You could try to swap sensors to see if one is bad.

 

[WREKS]

I have had overheats but they were not due to sensors or t-stats, only silt and sediment. If you do have an overheat, having a infrared thermometer and shining each cylinder by the exhaust manifold and comparing the readings with the good engine might be helpful. Hopefully, you can just blow most of it out. If you ran at 6k for 60 seconds that is optimistic. I think you are doing some good. But I would not continue to do that if you keep getting overheats.

 

[Julian]

https://jetboaters.net/threads/how-can-we-prevent-diagnose-and-eliminate-overheating-problems.27469/#post-457198

Flushing the engines may not be able to build enough pressure to evacuate all of the sand. If it were me I would put it in the water and run it hard to try to "blow" all of the debris out. Higher RPM's, higher cooling system pressures.

You could try to swap sensors to see if one is bad.

Look at the photos at the top of that thread. If you have sand packed in there, no amount of running hard is going to clear it. The only way to clear it will be to pull the head off. Running it hard and overheating it repeatedly likely won't end well (just my opinion).

 

[WREKS]

Look at the photos at the top of that thread. If you have sand packed in there, no amount of running hard is going to clear it. The only way to clear it will be to pull the head off. Running it hard and overheating it repeatedly likely won't end well (just my opinion).

Yes! Maybe what is in there starts to get 'baked' in. Just a thought.

 

[Rogandanny]

UPDATE: put both engines on the hose for another 20/25 min each today. Flushed them with salt off as well. Did some high rev clears at the end, put her back in the water and runs great, no problem!

In the water ran for 15 min @ 2200 RPM
10 min @ 6000 RPM
10 min @ 7800 RPM
15 min @ 2200 RPM and zero alarms/ overheat. Hand checked temp of engines before changing RPM each time and completely normal. Thanks everyone, seems like my problem solved itself!

 

[Julian]

UPDATE: put both engines on the hose for another 20/25 min each today. Flushed them with salt off as well. Did some high rev clears at the end, put her back in the water and runs great, no problem!

In the water ran for 15 min @ 2200 RPM
10 min @ 6000 RPM
10 min @ 7800 RPM
15 min @ 2200 RPM and zero alarms/ overheat. Hand checked temp of engines before changing RPM each time and completely normal. Thanks everyone, seems like my problem solved itself!

Thats awesome! I would still invest (they are cheap) in a laser temp sensor. Got mine on amazon for $28. Easy way to check one engine against another to see how they compare.

 

[Rogandanny]

Thats awesome! I would still invest (they are cheap) in a laser temp sensor. Got mine on amazon for $28. Easy way to check one engine against another to see how they compare.

Yes I have one in the garage need to dig it out.. definitely will come in handy in the future