01 Merc 90 2 stroke alarm?

  • Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 14, 2011 at 10:38 am #1238505

    My alarm went off yesterday and won’t shut off.

    First I thought is was the low oil alarm, but after taking off the hood, the tank was well over half full. I added another quart…alarm still going off.

    The telltale water is coming out at full stream and is cool. Since everything seemed to check out, we continued on our fishing trip last night putting 20 miles on the motor that was running flawlessly….except for the dang alarm.

    Which reminds me. when I turned on the key after hours of the motor not running, the alarm came on.

    Since it couldn’t be too hot at that point and there is plenty of oil…I’m guessing I have a bad sensor?

    How can I tell which one is bad?

    This seems like I should be able to fix this myself(?)

    herb
    6ft under
    Posts: 3242
    June 14, 2011 at 11:15 am #973112

    Bk, Mr. Obvious here. Since you’re not the mechanic that all of us would like to be, my first suggestion is to put away that 3lb maul you have in your right hand and from your left hand to your back pocket, put the screw driver and wire cutters.
    Now, sit there and wait for suggestions from those with knowledge on this subject.

    packingheat
    Reads Landing Mn
    Posts: 696
    June 14, 2011 at 11:20 am #973113

    I had a temp sensor go on a 60hp one time, a quick way to tell was to unplug the temp sensor and turn the key on. Good luck B.K.

    trumar
    Rochester, Mn
    Posts: 5967
    June 14, 2011 at 11:53 am #973118

    I also know that if you have a lose nut on the one of the wires to a sensor connected to the alarm it will also go off constantly.

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 14, 2011 at 11:53 am #973119

    Quote:

    I had a temp sensor go on a 60hp one time, a quick way to tell was to unplug the temp sensor and turn the key on. Good luck B.K.

    Thanks Herb…

    …and I’ll give the ol’ temp sensor a shot…if I can find it.

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 14, 2011 at 11:54 am #973120

    Quote:

    I also know that if you have a lose nut on the one of the wires to a sensor connected to the alarm it will also go off constantly.

    That is something to hope for…and I can ID a loose nut from 50 feet! Thanks Jeff!

    sgt._rock
    Rochester, MN
    Posts: 2517
    June 14, 2011 at 12:55 pm #973133

    Cut the wire to the alarm and run it. Oil and over heating?? Come on a real man never worries about that stuff.

    cpetey
    Onalaska, Wi
    Posts: 1193
    June 14, 2011 at 1:14 pm #973096

    Quote:

    Quote:

    I also know that if you have a lose nut on the one of the wires to a sensor connected to the alarm it will also go off constantly.

    That is something to hope for…and I can ID a loose nut from 50 feet! Thanks Jeff!

    But it’s the wingnuts that you have to be careful of.

    Angler II
    Posts: 530
    June 14, 2011 at 1:39 pm #973146

    The same exact thing happened to me. I pulled the alarm and never re-intalled it. I just alway’s make sure to have oil in the tank and that the motor is discharging water at it’s normal rate. I think they wanted $60 for the sensor which I thought was ridiculous!

    shew
    East Bethel, Minnesota
    Posts: 696
    June 14, 2011 at 1:41 pm #973149

    BK,
    Is this a remote oil tank with a reserve mounted on the motor, or a main oil tank mounted on the motor? If it is the reserve tank on the motor that tank needs to be full with no air in the line at all. If it is your main tank you may consider looking at the oil level sensor. Good luck wish could be more help

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 14, 2011 at 3:42 pm #973195

    Quote:

    If it is your main tank you may consider looking at the oil level sensor.

    All you guys have been very helpful.

    minnesota_tom
    Grand Meadow, MN
    Posts: 204
    June 14, 2011 at 8:22 pm #973286

    BK, We had a 75hp Merc that did the same thing. Turned out to be the low oil alarm. The Merc dealer in Red Wing diagnosed it right away. Unhooked it and ran perfect that way for several years. Just check the oil periodically.

    Just a word of safety. Never. And I do mean never, do what I did. Do not be in the middle of Lake Pepin, with the beeper going off, FW getting more irritated by the minute, and while I have the hood off and I am hanging off the back of the motor, I asked her “Honey, can you put it in gear and go a head a little bit for me?” Now keep in mind that she always sees me ease into the throttle enough to get it to plane out right away and then back off. After I had yelled enough to get her to stop so that I could release my death grip from the Merc, she (FW again) just had to ask me “what’s wrong? You told me to pull ahead” Well, next stop was at the dealer getting it checked out with driving lessons for FW first thing the following day. I still sometimes wonder if she didn’t do it on purpose….

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 15, 2011 at 4:30 am #973387

    They always act like nothing happened.

    Ralph Wiggum
    Maple Grove, MN
    Posts: 11764
    June 15, 2011 at 12:32 pm #973419

    My Merc did this exact thing last year. It was the oil sensor. I guess over time, the float in the oil tank eventually saturates and fails to float anymore, causing the constant alarm. Mine’s got the tank under the cowl. Had to replace the tank because it’s an entire assembly, but it solved the problem. I’m not willing to run without the alarm.

    Is it a contant alarm? I think constant is oil, intermittent is temp.

    jon_jordan
    St. Paul, Mn
    Posts: 10908
    June 15, 2011 at 1:54 pm #973451

    Quote:

    Is it a contant alarm? I think constant is oil, intermittent is temp.

    Opposite for Mercs. Constant is temp, intermittent is oil.

    -J.

    Ralph Wiggum
    Maple Grove, MN
    Posts: 11764
    June 15, 2011 at 2:15 pm #973459

    Quote:

    Quote:

    Is it a contant alarm? I think constant is oil, intermittent is temp.

    Opposite for Mercs. Constant is temp, intermittent is oil.

    -J.


    Now that I think about it, you’re right. I was trying to repress the memory of the beeping

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 15, 2011 at 4:57 pm #973523

    Guess I won’t know until I get down there on Thursday.

    It’s consistent.

    Where would the temp sensor be located?

    The sound is coming from my dash and not the motor itself if that makes a difference.

    Ralph Wiggum
    Maple Grove, MN
    Posts: 11764
    June 15, 2011 at 5:21 pm #973547

    What do you mean by “consistent”?

    Constant Alarm (temperature) = BEEEEEEEEEEEEEEEEP
    Intermittent Alarm (oil) = BEEP…BEEP…BEEP…BEEP

    Both with continue to beep if the sensor is bad.

    jon_jordan
    St. Paul, Mn
    Posts: 10908
    June 15, 2011 at 6:21 pm #973581

    If it is a constant alarm and you have a strong flow out the pee hole I’ll wager you have a thermostat that is stuck shut or does not fully open.

    -J.

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 15, 2011 at 6:38 pm #973586

    Constant Alarm (temperature) = BEEEEEEEEEEEEEEEEP

    Jon you may have hit it on the head. I touched the water after the motor was warmed…20 minutes of 3000 rpm…the discharge from the peehole was quite cold. Since this was when the alarm started singing, I was checking to ensure it wasn’t too hot.

    Although if it was a stuck thermostat, why would the alarm start sounding when the key was turned to the on position after 4 hours of not running?

    Now I’m back to a sensor being shot…right?

    jon_jordan
    St. Paul, Mn
    Posts: 10908
    June 15, 2011 at 6:44 pm #973587

    Pull the t-stat and do the boiling water test. Make sure it is working. Or just swap out for new one. Talk to a dealer, there may be 2 t-stats on that motor. You may find when you pull the t-stat that there is sand/mud/guck in the cooling passeges. Get that all cleand out!

    The next thing I’d do is install a temp guage. Just hook up the unused brown wire in you wiring harness coming off the motor. Should be loacted up under the dash.

    -J.

    herb
    6ft under
    Posts: 3242
    June 16, 2011 at 1:23 am #973662

    I coulda told you all that but I figerred I’d let Jon J be the hero.
    Thanks Jon J

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 16, 2011 at 1:45 am #973672

    Herb….

    Brian Klawitter
    Keymaster
    Minnesota/Wisconsin Mississippi River
    Posts: 59992
    June 16, 2011 at 11:29 pm #973920

    Just a quick update.

    Turned out to be the oil level alarm. Sounds like the float ends up sinking or getting stuck and as one poster mentioned above, the only way to fix it is to replace the oil tank at todays cost of $77.xx plus install.

    I’m looking at a couple other options other than replacing it, one being a string tied in a bow on my index finger. Since I carry an extra quart of oil in my boat for a reason… I feel replacing the tank is much less expensive than the cost of forgetting what the string on my fingers for.

    Ralph Wiggum
    Maple Grove, MN
    Posts: 11764
    June 17, 2011 at 1:00 am #973941

    Quote:

    Sounds like the float ends up sinking or getting stuck and as one poster mentioned above, the only way to fix it is to replace the oil tank at todays cost of $77.xx plus install.


    Nailed it! Write this down–I was helpful!

    Different motor, but I think mine ran just under $200 installed.

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