Overheating alarm

[Tommy Bierly]

Went out to watch the sun rise (my new thing) and while motoring around, my overheating alarm went off.

I don't think I was really overheating. Both pissers had a healthy stream of water. I came off the throttle and let the motor run water through it. Did that for a few minutes, turned it off and the alarm went off when I turned it back on.

seems to happen once a season. I'm in salt water; one person told me that salt accumulates on sensor and gives false readings. Another suspicion is a thermostat or sensor going bad.
Anyone else deal with this?
Pic from the morning.

 

[Dave burke]

Beautiful pic. Where is this?

 

[Tommy Bierly]

It's "Rocky Bayou" near Destin, Florida (Niceville)

 

[WREKS]

If I remember correctly, sensors do not make contact with water, only the metal housings. Maybe others will chime in.

 

[David Martin]

I don't think they are in direct contact with water at lease on my 2013 1.8L engines. Opps forgot to add Salt water is really rough on thermostats they can stick and unstick at will in corrosive salt water.

 

[212s]

I jinxed myself the other day...just had this happen yesterday while idling in weedy area and not paying attention - floated over some long thick weeds in 8ft of water and they blocked the intake grates and wrapped around the impeller shaft causing water flow to drop off. Shut off as soon as I realized what happened, opened the engine cover, pulled out the weeds through the cleanout plugs, and pushed throttles forward to raise the buckets and check for anything in there (nothing). Then turned the batteries off/on 5 times to clear the error. After it cooled down, I started both engines and ran fine the rest of the day although I had to clear the grates again after picking up some cavitation along the way...must have ran over more long weeds and sucked them up crossing another weedy area. Some of the weeds were 3-4ft long pieces wrapped like wire around the shaft...at first I thought I hit some fishing line or rope it as it felt like that on the shaft, but was able to rip it out with my fingers. I keep an Exacto knife on the boat if I do hit line or rope though.

 

[Tommy Bierly]

Thoughts on this as a possible culprit?

 

[WREKS]

That is biofouling, a microbial buildup from from the continually wet cooling system. Best thing to do to prevent that is: a day or two after flushing on the hose, dry run the engines for about a minute to start drying out the cooling system. Repeat the process again after the engines are totally cooled down. No water, no problem. Where there is water there is life. Try it!