1990 Mariner Horn Sounding please help

[kytoon]

Ok, The horn comes and goes but seems to almost always be associated with my wife shifting the boat and she does with a very slow push forward not the sharp engagement that I would prefer.

1. The oil level indicator is disocnnected already. Last merc mechanic said this year and model only has oil level alarm no pump alarm or any other alarm associated with the oil injectioin system. further he went on to say the oil pumps are not known for going out on these motors.

2. It's not overheating, thermostat and impeller have been checked and I have no problem sticking my hand on engine when horn is blowing.

3. Once the problem begins it will sound when the keys on but the engine is not. But then it might go away and not come back for a trip out or so.

Any help, thoughts, leads, would be helpfull.

Also I'm looking for a pdf version of the manual anyone know where I can get one.

 

[jhoelting]

Re: 1990 Mariner Horn Sounding please help

There are alot of post done on this subject. I have a 1993 Merc 175 with oil alarm trouble along with alot of other folks. The oil system has 4 or 5 different check offs. Yours might be one of them. Do a search in the forum for Mariner and Merc in the model years around your motor, and you'll find something.
Pump rotation sensor, low fluid sensor, could be a loose wire, check em out.

 

[kytoon]

Re: 1990 Mariner Horn Sounding please help

Most of them refer to multiple oil injection that could be the issue. However, my engine according to the mechanic only has the overheat warning and oil level indicator there is no other oil indicator.

I think what makes my problem unique is that it comes and goes. It may do fine but then the problem starts up. And won't go away until lets say the next day. I trailered it home for 30 minutes but problem was still there. But next morning get up and turn key over and all is fine.

From my readings elsewhere it seems the temp sending unit is an off on. Once the unit get hot enough (or thinks it's hot enough) it clicks on and stays on until the engine is cold cold So I'm going to bet it's the temp sending unit.

I'll post back after I replace it and go a couple of weekends without problem. And always open to new ideas.