engine alarms

[Heath]

My engine alarm has been going off lately. Its a constant beeeeeeeep when it sounds off, so i knows its temp related and not oil levels ( if i am correct )

engine: 90hp Mercury optimax saltwater edition 2002 model.

example: When i am driving, it will randomly go off ( usually at higher rpms, has not when under 3-4,000 rpms ). Every time, i have shut it down asap. and looked over the engine. Everything seems fine. I can turn the key back on and the alarm isn't sounding. If it was over heating, wouldst the alarm stay on until it is cooled? every time i have heard it, ive turned it off and can immediately turn the key back on and the alarm isn't sounding. The engine is 'peeing' cool water, and it seems to be running just fine. I flush my engine for 10-15 minutes after every use.

[onefishtwofish]

Could be a bad alarm module or a bad sensor. I think I recall, and this was a while ago, that in some of those engines of that time frame that constant could be oil pressure too. Google it for your year engine or call Mercury if you want to trouble shoot it yourself. If you want a good Mercury mechanic, there is one in Quincy. Speed and Custom Marine.

Oh yeah, forgot to mention, that mine did something very similar when I had an 01 200 HP and there was corrosion on the thermostats. It seemed to be peeing fine, but it must have been just enough of a turbulence to stop good flow. Pull them and have a look at them. Easy enough to peek at them.

[leonreno]

Need to take it to shop that can read the codes. Will tell you what is going on. The pee stream on a Optimax is from the air compressor and does not go through engine block. I would have it checked before something bad happens. Could be faulty sensor or something serious.

[bman]

Oh yeah, forgot to mention, that mine did something very similar when I had an 01 200 HP and there was corrosion on the thermostats. It seemed to be peeing fine, but it must have been just enough of a turbulence to stop good flow. Pull them and have a look at them. Easy enough to peek at them.

BING BING BING- Thermostats!! I had a sticky one that did the same thing. there are two on my engine so it looked like it was P-ing fine.

[Heath]

Will look at thermostats. Its just odd that i can instantly turn engine off, and turn key back on and alarm isnt sounding. If it was over heating, theres no way it could cool in less than a couple of seconds.

[onefishtwofish]

After doing some more readings and pondering on this I have a couple more ideas.

Continuous is: temp, low oil level, oil pump failure and the main one I forgot to think about: engine overspeed.

I get the alarm when I run high speed with the jack plate up and the motor trimmed. It over revs due to slippage. I trim down on the motor and the jack plate and all is good. The first few times it happened scared the heck out of me.

Check your oil level in your engine mounted oil reserve. Maybe high speed is pulling it from there and your tank is not keeping up. Just a thought.

If none of those are obvious, I agree, get the codes pulled. Bad things happen with all those.

[Heath]

Well, I have gone out twice since then. I took it easy the first time to see if i could pick out the variable. Ran without an issue the whole time ( i never went complete full throttle) and then otw back in, i was in Keaton, the engine alarm sounded, i quickly reduced throttle and before i could even turn the key off, the beep stopped. I let it idle for a second and proceeded slowly and it did not do it again. This was last Thursday. Then on Saturday, i avoided the scallopers and took my boat on fresh water for the first time (flint river), and i've never had it run that fast and smooth and alarm never went off. Going to keep cruising and taking it very easy and see if it continues. also, going to only fill oil tank up a quart at a time.

I have checked spark plugs and they didn't looked to have any foul signs at all and it still idles fine and the water coming from lower unit area is just as cold as the fresh well water i flush it with.
If it happens again, i will take it in for service for sure. But if it continues to perform as well has it has, then i will let it be. Its almost time for my second service of the year anyway.
thanks for all the advice.

[MudDucker]

You either have a bad sensor or a problem with the engine. I don't like to paddle, so I get my engine checked whenever an alarm sounds.