Overheat Alarm

[MCMoffshore]

I have a 2002 Mercury 125 ELPTO, 4 cyl. on an 18' Proline. There is a continuous BEEEEEEEEEP when the key is ON and the motor is OFF. I have changed the Thermostat and Poppet Valve and it's realated parts. Water is exiting the telltale with a strong stream and good pressure but the water pump and impeller are not new and the motor has not been dry started.

Reading an old thread with very similar details, I followed the instructions disconnecting the tan wire w/ blue stripe from the Temperature Sender but the warning horn does not turn off. The old thread suggests that the next thing to check is the Alarm Module? I tried to trace the wire back to the helm but can't locate it. Also, with my head in the helm and the alarm going off I haven't been able to find the location of the Alarm Module. What should I be looking for and where is this located?

Any help with this is greatly appreciated. Thanks, Gary.

 

[jigmister]

Re: Overheat Alarm

The alarm module is on the engine. The horn that sounds is all that will be found under the helm.
is this a 4 stroke?

 

[MCMoffshore]

Re: Overheat Alarm

Thanks for the reply jigmister.

I have looked at the Mercury parts schematic for my 2 stroke "2+2 cylinders" engine and can't locate the part or part number for an "Alarm Module". Tried to find a replacement part on the internet hoping to find a picture of the part and I could track it down that way, no good either. Is it one of the two small black boxes beneath the Starter? Or, if I follow the wire connections is the module located under or behind the oil tank?

Also, I can't locate the horn beneath the helm. My Merc wiring schematic says it will have a Tan wire and I have traced the 2 that I could find and unhooked them but still the horn beeeeeeeps. Thanks again.

 

[jigmister]

Re: Overheat Alarm

hmmm
I would look at the exploded views of your engine here http://www.mercurypartsexpress.com/us/

you will need the serial number off the engine and punch it in at the mercury site linked above.
I asked if your boat is a 2 stroke or not because 2 strokes will certainly have a oil alarm as well as temprature. if the oil pump stops or the resivour on the engine is low the same alarm will sound.

 

[MCMoffshore]

Re: Overheat Alarm

Yeah, there is a low oil alarm as well as temp. I had the reminder go off several years back, but I'm thinking the oil alarm was 3 distinct beeps and not continous?

Thanks for the link to the Mercury website, I have already been there and curiously they don't depict the two black boxes beneath the Starter, or at least I can't see them. I also looked at each of the pictured segemnts contents trying to find a part labeled Alarm Module or something similar, to no avail.

How about the warning horn, have you an idea as to where I might locate this under the helm?

 

[jigmister]

Re: Overheat Alarm

the one on my boat is tied to the main wiring harness in a net like material.

 

[MCMoffshore]

Re: Overheat Alarm

Alright, I found the warning horm and removed it. If it helps someone else in the future, I found the horm in the helm at the end of the wiring harness. It was hard to find as it was zip tied with a bundle of wires and I couldn't see it until I started cutting ties away. The part number is 816492 6, and the cost is $15. I'll replace it and post comments. Thanks again for the help jigmister.

 

[jigmister]

Re: Overheat Alarm

I dont think the horn is the problem. when it gets power it sounds. its doing that.

 

[MCMoffshore]

Re: Overheat Alarm

I see your point. I guess I was thinking that the malfunction of the horn was that it was stuck ON, it sounds like that isn't probable?

So, that would lead me back to the elusive "Alarm Module" as the source of my problem? Could I test the warning horn by attaching the Purple 12v wire and leaving the Tan w/ blue stripe wire off? I already did that when I disconnected the Tan w/ blue strip wire from the Temp Sender but this would tell me if the problem was the Oil Alarm (Sender) or the Alarm Module which I haven't found yet.

 

[jigmister]

Re: Overheat Alarm

not sure on that. I would need the manual to that motor. the manual I have for 175hp has a trouble shooting section for the alarm.

I am sure there are people here to chime in with more knowlage of your engine than I.

 

[MCMoffshore]

Re: Overheat Alarm

I tested the horn on the Purple 12v wire and it is fine, then when I touch the Tan w/blue wire the horn sounds. The Horn is fine, thank you jigmister for pointing that out. I have plenty of oil in the side mounted tank, so I think my next job is to remove the attenuator plate covering the carbs and also the oil tank to access the oil pump and sender? Or, I can remove the lower cowling and access the oil injection area from beneath? Just guessing at this as I am out of my league, how would you proceed?

 

[jigmister]

Re: Overheat Alarm

I would get the book out and go through the trouble shooting guide.
The oil tank must have a float the sounds the alarm when low. maybe its sticking? just a guess.

 

[MCMoffshore]

Re: Overheat Alarm

I got my flashlight and reached under the oil tank and found the connection between the Tan w/ blue line wire to the Blue wire that goes into the bottom of the oil tank. When I disconnected them the horn stopped. The Blue wire leads to the Float Switch Assembly. I have a full tank of oil that I will have to figure out how to pump out if the float switch needs replacing. If the float switch is just stuck, is it safe to stick a probe of sorts into the tank to un-stick the float? Or is there something else I can do here. Also, is there a way that I can check to see if the oil pump is actually working?

I know, I need to buy the manual for my engine. I always used to take the boat in for service so I never had to buy it, but, with the passing of time has come a change of economic fortunes. Now I can barely afford the parts I need to fix the boat and I am trying to do it all myself, $75 for a service manual, really?

 

[CharlieB]

Re: Overheat Alarm

$75.00 for a factory manual may be the best investment you ever make.

The oil tanks on the in-line motors have a poor reputation for an adhesive failure holding the magnet to the bottom of the float. The magnet falls off, landing on or near the switch and the oil alarm starts beeping as soon as the key is turned on. The float cannot be repair, a new tank must be installed.

The magnetic switch fits into a hollow in the bottom of the oil tank, its two blue wire should plug into two blue wires coming from the alarm module.

Tan w/blu is temp sensor wires and should NEVER be connected to any blue wire.

An oil alarm is a continuous rapid beeping.

A temp alarm is a solid tone.

Some service manuals are still available on-line, check out the links in one of the stick posts at the top of thos forum.

 

[MCMoffshore]

Re: Overheat Alarm

CharlieB, thanks for the help.
I just checked on mercuryparts.com to see how much a replacement oil tank is going to cost. I found it odd that they don't sell the Oil Tank Assembly 828362A 2, with the Float Switch Assembly 12886A 6, included? I think I'm missing something. If the magnet falls off of the float switch disabling the float mechanism and triggering the alarm, I understand you are saying that it is broken and must be replaced. But why does the whole oil tank need replacing when the float switch is going to have to be purchased seperately and installed by me when the parts arrive? Can I just pump out my oil tank and replace the $14 float switch assembly. I am just assuming the float switch is bad for now, it could be the oil pump that is my problem. Is there a way for me to test the float switch and / or the oil pump to see which is bad?

 

[JohnChandler]

Re: Overheat Alarm

The Float motion is transfered through the plastic to the switch by the magnet. This design isolates the switch from oil contamination. I can see the round magnet at the bottom when I lift the float. I am going to attempt to reattatch the magnet to the float with some type of oil resistant silicone. It looks like the float is attatched with a locking ring at the top. If it doesnt work I will have to buy a tank anyway. Its worth a try.