In Middle Of Fixing Oil Alarm Problem Need Advice

[jack007]

Hi, thanks to those on this forum, Saumon and others and on the All Experts and other forums for great advice on my 1989 Mariner 90hp engine oil alarm problem. I'm right in the middle of diagnosing/fixing this, making good progress (I hope) but need more advice, so I thought I'd start a new thread. So far....The engine was running fine when the oil alarm started and would not go off. Plenty of oil in the tank, smoke and temp seemed normal. (It's definitely the oil alarm beeping not the continuous overheat tone). At 1st I thought it was a wiring problem with the horn but confirmed it was not. Following advice I located the oil module (it's a 2"x2" black box under and behind the engine mounted oil tank, with the 5 wires going in and out of it). I disconnected the tan wire and the alarm stopped. I reconnected the tan wire (the alarm came right back on) and disconnected the 2 tan-to-blue wires going from the bottom of the oil tank to the module, the alarm stopped, the horn test beeps when ignition is turned and engine seems to run ok. (The other wires from the module are a purple one to battery, and a black one that goes back by the cylanders). My question is doesn't this have to mean the problem is just a stuck float or bad sensor in the oil tank? Is there any way it could still be the oil pump, the module, heat sensor or some other part of the injection system? If it's just a stuck float or tank sensor couldn't I just make sure to keep the tank full and leave the wires disconnected? I sure don't want to harm the engine, please advise, and thanks for the advice so far.

 

[saumon]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

you got it: stuck or bad float sensor! you could try removing and cleaning it. if it doesn't solve the problem, then change it. Anyway, the intermitent beep doesn't mean that the engine isn't getting oil, it simply is an indicator of a low oil level in the tank...not related at all with the oil pump. If this one fail, your engine will for sure overheat and then this is the "other" wire (the one that goes in a hole between the top of two cylinders) that will do is job: this is the heat sensor. Just to be sure, the heat sensor is very easy to test: unscrew the phillips screw, pull the sensor and, with ignition "on", ground it to block. You should hear a constant beep.
Back to the low oil level alarm, yes you could leave it disconnected but this sensor is a cheap foolproof insurance...just in case you forgot!

 

[j_martin]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

Here's how it's supposed to go.

Oil alarm goes off. You check it out.

A. You find out the boat oil tank is empty, and there's a little air in the tank on the motor.
.......Dummy, but you have 1/2 hour at wot to get home.

B. There's oil in both tanks.
You assume the oil pump is bad, transfer some oil to the main fuel tank, (prox 50:1) and safely get home.

It's all in the mercury owner's manual.

That said, a simple close on alarm switch is a rather sophomoric design as it doesn't compensate for a bad connection or wire, however that's the way Merc made it. Good side is, disconnecting it makes it look all good, and makes the troubleshooting easy. If disconnecting it shut off the the alarm, then the switch is bad. (the one in the oil cap.)

Happy boating
John

 

[floppy jaloppi]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

Hey guys how we doing have a quick question my alarm does not beep when i turn ing on and also doesnt beep when running on ears on land only beeps in water above idle.also when i take res cap off on motor should it beep i checked sensor with meter working fine please if anybody can help thanks

 

[Nauset #37766]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

The two wires that go to the bottom of the tank are connected to a reed switch that goes into a blind hole and is held in with one screw. You can remove it and no oil will come out, just take the screw out and it will drop down out of the tank. If it still beeps with the switch down out of the hole, the switch is bad. Most likely though the ring magnet has came off of the float and dropped down and the only fix for that is a new tank. It's not a bad job to replace the tank and bleed the lines and the price for the tank isn't too bad. Be sure to replace all of the lines from the tank to the oil pump and from the oil pump to the fuiel pump, they crack when you just look at them it seems.
Bill

 

[CharlieB]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

SLOW Down and back up a bit.

You said that you disconnected the TAN wire that leads to the Temp sensor and the beeping STOPPED?

Reconnecting it and the beeping resumed.

Disconnecting the Blue wires to the magnetic tank float switch and the beeping stopped.

Reconnecting them and the beeping resumed.

Usually, if disconnecting either or both the blue wires stopped the beeping alarm it would indicate a problem with the switch or the float.

HOWEVER, if disconnecting the TAN Temp sensor wire stops the beeping oil alarm, then the module is bad.

RETEST disconnecting the tan wire to the temp sensor to confirm BEFORE you order an new alarm module.

Grounding the tan wire should give you a constant beeeeeeeeeeep to indicate an overheat.

 

[CharlieB]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

Floppy, you really should start a new thread to ask about your problem.

This thread is almost a year old.

 

[joed]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

If you disconnected the tan wire TO the control instead of the tan to the sensor the beeping would stop no matter what the problem. There is a Y connector there that joins the temp sensor and the oil module to the single tan wire back to the control.

 

[floppy jaloppi]

Re: In Middle Of Fixing Oil Alarm Problem Need Advice

if i unscrew the oil cap on motor res it should set alarm off right and when i turn key on it should beep right when i do either the alarm does not come on by the way i know alarm is good tested it from back at motor by grounding wire that goes to alarm thanks again for any help