overheat dash warning

[itsdgm]

Hello All! We have a 2011 AR210 that keeps showing a light on the dash (solid light on starboard side) for water temperature. My hubby has changed plugs, thermostat, looked at the intake filter, changed the engine temp sensor and thermo sensor. What the heck else could it be? I want to ride in my boat for more than 5 minutes.

Welcome @taylr222 and sorry to read about your issue.

Additional info might help diagnose your issue. Here's a few questions about the boats history that come to mind:
1. How long have you owned the boat?
2. Fresh water or Salt water use?
3. Any idea of how many hours on the engines?
4. When did the problem start? Was it right after any work was done on the boat? Any electronics added to the boat around the time the issue started?
5. Do you trailer the boat each time out, or do you keep it in the water?

A few things that come to mind right off the bat would be:

1. Possible blockage in a cooling line, exhaust or water path inside the engine.
A. One way to "help" diagnose this would be to blow out the hoses with an airline.
B. Second, get a infrared temp sensor and run each engine on the garden hose. Check several temps above each cylinder and several at each exhaust outlet. Compare the affected engine readings to the non-affected engine.

2. Does your boat have dual tachs that contain the overheat temp lights? If so, it's a long shot, but you could swap them and see if the issue follows the tach or stays with the engine.

3. Do you have access to a copy of Yamaha Diagnostic System/Software (YDS)? It enables you to look at several sensors on the engine with a laptop. Might be useful for you. Possibly a member nearby has a copy and could help you out.

IMHO, if it's not a bad sensor or the spark plugs, it's usually a water blockage issue somewhere in the cooling system.

Sorry to answer your question with so many other questions. But more info might help better diagnose it. It does sound like your husband has already addressed quite a few of the "usual suspects". Hopefully you can nail down the culprit soon and start enjoying your boating season again.

Edit: also, how old are the spark plugs? Replaced before or after issue started?

 

[Gym]

@taylr222 you also want to look at the water pick up located on the left side of each nozzle as viewed while standing behind your boat. With the throttle lever in forward you can look up inside the nozzle, to the left side to see if the pick up screen is clear. You can also easily remove this screen, for better inspection, by removing the 4 small bolts on the outside of the nozzle.

 

[Scottintexas]

@taylr222 glad to have you on board, check out this video from our FAQ section from one of our members about how the cooling water flows through the system,

https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/