Oil Alarm on 1985 Mercury 150, Help?

seadog · 06-07-2009, 09:42 AM

My oil alarm is beeping at me. The first time it happened I thought the tank was maybe to low so I added another gallon of oil. Then the next time we went out it did it again.

I have a 2 tank system(one main tank that holds about 2 gallons that pumps up to tank on the the motor). The one on the motor is full to the top, the main res. has about 1 1/2 gallons in it. I can run the motor for a couple of minutes before the beeping starts. I really have no idea how the system works, so I don't really know where to start on fixing it. I am mechanically savvy but don't know where to start trouble shooting this problem. Anybody got any experience with this type of problem?

Help
I'm not made of money so I would like to fix this myself.

Lurp · 06-07-2009, 09:56 AM

My sportjet has the same setup
There is a float in the cap on the tank at the motor that turns on the alarm when the oil gets low
Sounds like the float has sunk or the switch in the cap has defected to the enemy
I would remove the cap and with an ohm meter attached to the two wires on the cap move the float up and down
Also check the float for damage

seadog · 06-07-2009, 11:23 AM

Thanks I'll try that, anyone else?

fishgetter · 06-07-2009, 12:24 PM

I have a 91 150 and had issues, the first issue was solved by filling the top tank on the motor, it seemed when ever I filled the lower main reservoir a air pocket would move to the top tank, topping it off solved the problem.

I has an alarm come on and it would not go away, it ended up being the oil sending unit, black box, cost me $200 to have it replaced. I asked the mechanic how he tested for it and he advised he swapped out parts until the alarm went off, not scientific and not easily done if you do not have a shop full of good parts.

Good luck!

seadog · 06-07-2009, 06:33 PM

I don't see a tail between the legs icon so I guess I'll just wing it. The tank on my motor that appeared to be full, wasn't, it was just stained blue on the inside. I took the cap off and it looked to be about 1/2 empty. So I pulled the cap off the lower tank that has the hose going up to fill the upper tank, and the suction tube has a screen on it and it seemed to have a nasty pastey scuzz on it that wouldn't let the oil flow through it

! So I cleaned off the screen and put it back together took it down to the boat ramp to run it. The oil alarm continued to beep at me after I started it, so I took the cap/ float switch off the motortank and lifted the float switch and the alarm went off (YAY). Then I watched the level in the motor tank while the engine continued to idle and it filled up with oil while I watched. So I put the lid back on and ran it up the river for a mile or so and everything seems to be hunkydory. So lesson learned, take the lid of of the tank even though it looks full, it may not be. Such a simple fix. Maybe the combination of different oils made a sludge that clogged the inlet screen. Or that after 24 years maybe it just got gunked up and needed cleaning. I hope that if anyone reads this and it helps them fix their problem then great! It isn't always as bad as you might make it out to be in your mind. Thanks for looking and for the ideas!

fishkisser · 06-08-2009, 07:22 PM

Boy that sounded like a close one ...

Glad you got the mystery solved ...

tear-a-bite · 06-24-2009, 09:36 AM

glad to hear it worked. my 200hp was doing the same - and also beeping alot when i'd hit waves, bounces, etc.

turns out the wiring at the top of the cap for the sensor were starting to go. i replaced the cap sensor and it fixed it. i also put zip-ties on the wiring just before it dropped into the cap, and it fixed the old wires (kept them from wiggling) and has helped the new cap, to keep the wires from wiggling and wearing out. hopefully.

hope it helps. took me a while to figure it out