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I have a 1987 Johnson 150 on an 1987 18 Outrage. This spring the buzzer under the console started to go on continuously when the ignition was turned on. It would not stop when the engine was started. I filled up the oil container but that did not help. Took it in to get a spring tune up. Once the shop started the engine the buzzer stopped. When I picked up the boat it was doing it again. We verified that it was the oil container sensor by disconnecting the wires. I decided not to replace the sensor ($200) as I am good about keeping the oil full and will just leave the wires disconnected for the summer.

Is it possible to clean the sensor in the oil container and will this solve my problem. If it can be cleaned how is it done?

Should I have any concerns by leaving the wires disconnected. I will cover the positive end so it will not come into contact with anything.

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Yes you should have concern. I had the oil sensor go out in my 100 hp merc. tank. The tank is built onto the motor. I also took pride in thinking I had enough smarts to keep oil in the tank. I went to Fla. on a fishing trip. I filled the boat with gas and the oil tank with oil. After a couple of days of fishing on the flats I topped the gas tank off , to fish the last day. I did not fill the oil as I knew it would not use a tank of oil with only one tank of gas. So when the motor locked down, because the oil ran out, I had to wonder what went wrong. Turns out a check valve in the oiling system stopped checking and created a steady vacuum on the oil tank. So it got a lot of oil for a while, then no oil for long enough to burn it up. 2500 dollars spent because I was smart enough to know how much oil the motor would use under normal conditions. So the oil sensor would have alerted me of the failure in the system ,not just that I forgot to put oil in the tank.

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I don't think any of us would disconnect the smoke alarms in our homes just because we are careful and don't smoke....

That is an accident waiting to happen as Bake mentions above.

I have bought a couple of brand new oil tanks on eBay for $40 to $50... I would replace your entire tank ASAP.......

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I'll chime in with a different outlook. The oil level sensor in a pre-1996 product is a foam float with a metal disk for electrical contact. There are electronic chips inside the oil pickup that generate the beep every 20-40 seconds when the oil level gets low. Very often the electronics go flakey and give various false horn signals to the boat operator. They may sound continous, a warble, a faint beep occationally, or a tone that varies with rpms.

Since the low oil alarm is only an indicator of remaining lubricant the oil tank, a visual inspection works as well. In my opinion it is not worth the several hundred bucks to have something that you can just keep your eye on occasionally.

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I ran my 91 Merc 115 for many years with the broken oil float sensor jumped out without issue.

Its a simple risk assessment only you can make. Personally I've always visually checked my oil level before every outing and never let the reservoir get below halfway.

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For sure this is a personal decision.

I run twin Johnsons on my Revenge and due to the problems that Seahorse outlines above, have now disconnected both oil level sensors. For a year or so, I kept a small piece of wire next to the oil tanks, and would jiggle the float until the alarm shut off. when the day came that jiggling the float would not shut off the alarm, I simply cut the wire at the tank and later disconnected the leads under the cowling.

If I ever fry an engine due to running out of oil, someone can say "I told you so", but in the mean time, I will rely on my pre-launch checklist that includes a line for "oil tanks full".

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Alarms are a very safe way of knowing what your engine is doing. I trust them and use them. Have it fixed.

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Either fix the sensor or scrap the oil injection and mix your fuel.

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After advice from members on here I replaced my non functioning alarm when I got my boat a few years ago. It alerted me to a prior VRO issue and also I believe the same buzzer operates the overheat sensor. Well worth the money

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I guess I give folks too much credit for being competent enough to manually monitor the engine's oil level.

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Lol, yup.

This is part of my pre boating checks.......make sure I have enough oil and I've never had an issue.

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My oil sensor triggered with plenty of oil in the tank. If there is a failure within other parts of the system to deliver oil, the sensor will let you know that the oil is not being fed through the system. How would you feel if you looked at a tank with oil in it, but your engine still seized because it wasn't getting the oil in the tank? My next door neighbor's Merc 90 is an anchor now because the oil injection system failed in his engine.

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I suppose I am not as smart as those who never leave the dock without checking the oil level. My screw up came after running the boat for three days and using less than one tank of gas. I really did not need gas when i topped the tank, but went on to the fuel dock with the guy who needed gas to fish that day. under normal conditions there is no way I should have needed oil in the tank. I actually had a gallon on the boat. I looked at my repair bill today. The check valve that caused my tank to use much more oil than it should have was 12 dollars.

One other thing that might make a difference is the fact that my tank was on the motor and it was not a simple glance to check the level. If you have a external tank in a obvious place it might be easier to monitor it.

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The oil level sensor on my old 115 Merc has nothing to do with any of that. It was a simple magnetic float switch that triggered the buzzer if the oil level dropped below a certain point. There was also a separate over temperature sensor. Something I'd definitely prefer to have functioning.

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See this article if you want to keep everything in tack...............
http://www.whalercentral.com/articles...ticle_id=9

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I would never advocate disabling the warning horn system.

For those not familiar with the OMC warning system, bear in mind that there are multiple sensors that can trigger an alarm including:

1. High temperature at the cylinder heads.
2. High vacuum in the fuel system.
3. No oil at the VRO pump.
4. Low oil level in the remote oil tanks.

Disabling one sensor is not the same as disabling the warning system.

The comments about other engines don't really apply. With the OMC warning system, the operator will still be alerted to an oil problem before damage is done to the engine, even without the sensor in the remote tank.

If I had a Mercury engine and the one and only oil warning came from the oil level sensor, then I would replace the sensor. If I had only a small oil tank integral to the engine, I would replace the sensor.

The original poster has a 24 year old Johnson engine with a remote oil tank. Does it make sense to make an unnecessary repair and spend 10%-15% of the value of the engine on a sensor that can be easily replicated with a foolproof sensor built into his head (eyes)? Not in my opinion.

In my mind it's better to get in the habit of checking fluid levels before leaving the dock - rather than find out 20 miles offshore that the oil is low - IF the sensor even works properly.

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I just ordered a new oil sensor today for my 1991 merc 40, it cost 14.98. Merc calls it an oil level switch.
When I bought the boat a few weeks back I noticed the two wires were disconnected, I plugged them in and the buzzer went off . The prior owner just unplugged the wires to kill the buzzer.

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Seems to me the prior owner wasn't very smart.

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If you were pre-mixing the oil, the buzzer isn't needed.

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He never stated he is pre mixing his fuel. He is using his vro.