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Mercury 115 hp low oil alarm

yap_yap

Contributing Member
The low oil alarm on my 1992 m

The low oil alarm on my 1992 mercury (115 hp) will not go off although the oil tank if full.
Can any one provide the answer ?
 
"does the alarm come on as soo

"does the alarm come on as soon as you turn key to on position? if so you need a new warning horn modual. if not there is a sensor in the oil tank with two wires comming out blue i think disconnect see if horn stops if so prob in tank may be bad or float stuck. most common warnig horn modual black box 3"x3" has two s/s 8mm bolts mounted bottom of engine block strbd side usually purple, black 2 blue wires will cost about $94.00 depending on serial # post more info about what you are doing when horn sounds is it solid or pulsing"
 
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Shawn,you were on the mark,have disconnected blue wires and horn works as normal,eg one beap when key is turned on,so it looks like the sensor in the tank.
Do you have to remove tank to get at the sensor ??"
 
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I have removed the oil tank and find that the wires are connected to a rubber probe about 5 mm dia and 50 mm long held in place with a screw and washer,this slots into a devise at the bottom of the tank,do I replace the devise as well as the rubber probe ??????"
 
"Brian,

The problem is the


"Brian,

The problem is the float in the oil tank. This is a very common problem with the older models; it was corrected in later models.

The float has a magnet that is glued to the bottom of the float. It becomes loose and does not rise with the float so the alarm goes off. The magnet activates the magnetic switch in the probe.

In later models the magnet is attatched to the top of the float so this problem does ot occurr.

You can solve this problem fairly easily. The float is secured to the shaft that it rides on by a washer that bites on the shaft. You have to make a tool that you can reach into the tank with and pull upwards on the center of that washer. It will slide up and off the shaft, and then you can take off the float and magnet and glue them back together. Then just put the float back on and push the washer back into place.

Do not try gluing the magnet to the top of the float. It will not work on the older tank.

Tony"
 
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