Merc 115 Outboard Alarm issues -again

[JPC6000]

Looking for any ideas.

I have a Merc 115 outboard that has been driving me crazy with the over temp / low oil alarm. Took it out for the first time this year, alarm sounds when key is first turned and goes off - normal. Drive out to fishing spot, turn off motor but key is still in on position. Troll around for at least three hours with the kicker, and all of the sudden the alarm goes off, continuous beep when the motor is not even running. I have had the motor into the shop, they couldn't get the alarm to go on. Impellar has been replaced at the begining of last season and it is pumping strong, the mechanic ran the motor for an extended period of time while checking engine temp with heat gun - not overheating. The oil level in the resovior always goes down when I run, it never has been below a 1/4 tank since I have owned it.

So, now what? Do I have a short somewhere? Is the low oil level sensor inside the resovior bad?

All suggestions / ideas welcome.

Thanks,

John

[HemlockNailer]

John, I have the same motor and the same problem. My alarm comes on while trolling. If I turn the engine off it will stop for a few minutes but then come back on. I have had it in to two places and still have the problem. If you find the answer let me know, I am about ready to disconnect the alarm. Alan:confused:

[double trouble]

this seems elementary ,but did your dealer replace the warning system sending unit and run an ohm meter on the wires to and from the sending unit.did they clean or replace the oil tank screen? did they run a continuity test too looking for a short circuit.did they also tighten and put dielectric grease on all the connections.did they isolate this circuit and run a seperate wire for it i'd bet not. most mechanics are too busy, not very good at electricity, or lazy to do the job right. its just not that hard but they don't to waste half a day on a job they might not get paid for if it is warranty work.

[spendit]

I have the same situation (Merc 50HP, 4 -stroke, '99), replaced H2O pump, sensor and the dealer could not duplicate problem:mad: . Trolling at almost idle, it goes off and somewhat in to "gardian" mode. Lets me rev it up and goes away for a while, then back on again, even though oil level is right and pumping water:confused:

What I have concluded and how: First I let it go into "buzz" mode, then reach back and put finger over whitness hole - it shuts off. So I change H2O pump (housing, impellar,..) still goes off:dizzy: I have found that the sensor is located at the upper most cylinder, so doubt much cooling is getting to it.

Fix:I fabricated a smaller orifice that fits into exsisting "pee hole". I can see a stream - though not as much flow and the alram does not go off. If I forget this brass insert, the alarm comes back on. Has been that way for three years now.

One mechanic told me the tube that fits into the head can overheat and crack, thus not enough water into cooling jacket. I checked it out, looked good and even replaced it once, still had the problem until I put the orifice in.

[JPC6000]

I might have a lead...

I read on a an iboats forum that if you ground out the temp sensor the alarm will sound. So, you might want to check and the conditions of the wires to the temp sensor they might be getting grounded somewhere.

Still looking for the root cause of the problem,

John

[HemlockNailer]

Thanks for all of the good info guys. The mechanics that I had the boat into previously were mostly at a loss as to the problem. They want to start replacing parts until they hit on the right one(on my dime of course). I'll try your suggestions and see if I can find the cause.

[bignoccursg]

Is your 115 still in the upright position when you are using your kicker? I have a 115, no kicker, but in a good chop my alarm will go off every wave if I have less than 1.5 quarts of oil in it. I dont think it will hold about 3 quarts total. I could be way off, but I think my alarm would be going off due to low oil indicator if my key was on with my motor tilted up. Next time it happens put more oil in it and see if it stops.
Please post the results if you ever figure it out. Lots of us running that motor.