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Author Topic:   Overheat alarm

newt posted 03-03-2003 08:48 AM ET (US)
I installed a brand new Mercury 90 hp, 2 stroke on my Montauk last summer. I had them use the old controls. I want to make sure I have a working overheat alarm.
Where would the alarm be located, and how do I test it? Would the entire assembly come new with the engine, or is the sensor on the engine and the alarm buzzer part of the old controls, etc?
Clark Roberts posted 03-04-2003 06:08 AM ET (US)
The alarm (buzzer) is located inside the control box if side mounted control and underneath (strapped to wiring harness or cables) if benicle (sp?) type control. Most have a self test feature which activates the buzzer momentarily when ignition key is turned on. If you don't get this "beep" when ignition is turned on then buzzer may have been removed or alarm circuit is faulty. A correctly operating system will beep steadily on overheat and will beep, beep, beep on low oil. Clark
newt posted 03-04-2003 07:44 AM ET (US)
Thanks Clark. I hear no beeps at all - ever. I will take that as an indication the buzzer is gone. Would the new motor have come with a sensor installed? Or do I need to purchase the entire assembly?
Clark Roberts posted 03-04-2003 12:17 PM ET (US)
Newt, the buzzer comes with the controls and is wired in place (either side box or benicle) and the signal comes from an alarm module on engine and is wired up when harness is plugged into engine connector.
skred posted 03-05-2003 09:58 AM ET (US)
On my 2001 Merc 50 4-cycle, I asked the dealer why I heard no beeps when starting up, and he said Merc discontinued the startup beep features on the motors (at least the 50 hp). I'm pretty confident in the dealer's explanation, but I'm still a little worried - so I'm going to see if I can get an answer from Mercury.
John O posted 03-08-2003 12:55 AM ET (US)
related to this topic: What if I use Morse Controls on a Merc 75hp 2 stroke 2001? Could the alarm be on the ignition switch?
Clark Roberts posted 03-08-2003 08:37 AM ET (US)
Skred, let us know what Mercury says about the "buzzer test at first key turn"... my Merc 115EFI four strok does not beep at first turn and I was told by dealer that they don't have that feature on the 4 strokes. This is strange since it's such a good feature...I use a temp gauge, water press gauge and an oil press gauge and I monitor them closely. I know that the alarm buzzer works however,having once had blocked intake from weeds and temp alarm sounded... Happy Whalin'... Clark
PaulVT posted 03-10-2003 08:00 PM ET (US)
Skred & Clark,
I have a '98 Merc 50 4 stroke I bought used with a Dauntless 15. It bothered me that I never heard a 'prove-out' beep of the alarm when starting the engine. It took a bit of digging through the service manual to figure it out, but the alarm on my engine is not powered by the battery, but rather by the ignition coil under the flywheel. I guess the oil pressure comes up fast enough while cranking that the sensor is satisfied before there's power to trigger the alarm, or the circuitry is smart enough to delay a bit. The windings that power the CDI (capacative discharge ignition) module are independent of windings that charge the battery.
To convince myself there was an alarm and that it worked, I measured the resistance of the oil pressure switch (to ground) with the engine not running to be 230 ohms. I then ran the engine, connected a 230 ohm resistor from the sensor lead to ground, and the alarm sounded. Further, the alarm latches. That is, once triggered, it continues to sound until the engine is stopped.
Both the low oil pressure switch and the over-temperature switch connect to the CDI module. An ouput of the CDI connects to the wiring harness which leads to the alarm inside the console on my boat. I haven't tried to simulate an overtemp condition, but I feel more confident knowing the alarm is present and sounds off.
This may not help newt with his question that started this thread, but it may be useful to some.
Paul in Vermont - where there's 18"+ of ice at the launch ramp.
captbone posted 03-10-2003 08:21 PM ET (US)
I dont know if your motor has a system similar to OMC's S.L.O.W which brings the RPMs down and the engine starts to shake. If you do have a system like this then no worries. I used to run a 140 Rude with no guages or horns and I never worried. When it got a little hot it would slow down automaticly and shake like an sob. When it cooled down it would let you throttle back up. And this was a 1990 motor. IF you have a system like this then you will be fine(you should have it) for more protection also consider adding a water pressure guage.
triblet posted 03-11-2003 10:46 AM ET (US)
My '96ish OMC SLOW won't let you throttle back
up until the engine cools off, AND you shut
it down and restart it.
Chuck
skred posted 03-11-2003 03:57 PM ET (US)
No reply for Merc yet, but at the dealer's yesterday, he said they don't "post" (power on self test) the beeper any more. To test this, we turned on the ignition of a new 2002 60 hp, and - no beeps. Then a 90: no beeps. He says Merc is satisfied with their electronic sensing system that automatically cuts throttle, etc if any system goes out of operational parameters.
lewain posted 03-11-2003 07:08 PM ET (US)
Under Cowling at back of engine you will see a wire that goes into your head between the cylinders, there is a joint in the wire that will seprate. Pull the wires apart turn on ignition and stick a small screwdiver in the connection point and then ground to head alarm should sound if working
Clark Roberts posted 03-12-2003 07:49 AM ET (US)
Seems as though it would be easy to just install a buzzer "test" switch (momentary push type)on console... just a simple grounding circuit of the overtemp sensor... hummm???? I may just do that since I tend to go overboard (no pun intended) on everything else! Happy Whalin'... Clark ... Spruce Creek Navy

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Author	Topic: Overheat alarm
newt	posted 03-03-2003 08:48 AM ET (US) I installed a brand new Mercury 90 hp, 2 stroke on my Montauk last summer. I had them use the old controls. I want to make sure I have a working overheat alarm. Where would the alarm be located, and how do I test it? Would the entire assembly come new with the engine, or is the sensor on the engine and the alarm buzzer part of the old controls, etc?
Clark Roberts	posted 03-04-2003 06:08 AM ET (US) The alarm (buzzer) is located inside the control box if side mounted control and underneath (strapped to wiring harness or cables) if benicle (sp?) type control. Most have a self test feature which activates the buzzer momentarily when ignition key is turned on. If you don't get this "beep" when ignition is turned on then buzzer may have been removed or alarm circuit is faulty. A correctly operating system will beep steadily on overheat and will beep, beep, beep on low oil. Clark
newt	posted 03-04-2003 07:44 AM ET (US) Thanks Clark. I hear no beeps at all - ever. I will take that as an indication the buzzer is gone. Would the new motor have come with a sensor installed? Or do I need to purchase the entire assembly?
Clark Roberts	posted 03-04-2003 12:17 PM ET (US) Newt, the buzzer comes with the controls and is wired in place (either side box or benicle) and the signal comes from an alarm module on engine and is wired up when harness is plugged into engine connector.
skred	posted 03-05-2003 09:58 AM ET (US) On my 2001 Merc 50 4-cycle, I asked the dealer why I heard no beeps when starting up, and he said Merc discontinued the startup beep features on the motors (at least the 50 hp). I'm pretty confident in the dealer's explanation, but I'm still a little worried - so I'm going to see if I can get an answer from Mercury.
John O	posted 03-08-2003 12:55 AM ET (US) related to this topic: What if I use Morse Controls on a Merc 75hp 2 stroke 2001? Could the alarm be on the ignition switch?
Clark Roberts	posted 03-08-2003 08:37 AM ET (US) Skred, let us know what Mercury says about the "buzzer test at first key turn"... my Merc 115EFI four strok does not beep at first turn and I was told by dealer that they don't have that feature on the 4 strokes. This is strange since it's such a good feature...I use a temp gauge, water press gauge and an oil press gauge and I monitor them closely. I know that the alarm buzzer works however,having once had blocked intake from weeds and temp alarm sounded... Happy Whalin'... Clark
PaulVT	posted 03-10-2003 08:00 PM ET (US) Skred & Clark, I have a '98 Merc 50 4 stroke I bought used with a Dauntless 15. It bothered me that I never heard a 'prove-out' beep of the alarm when starting the engine. It took a bit of digging through the service manual to figure it out, but the alarm on my engine is not powered by the battery, but rather by the ignition coil under the flywheel. I guess the oil pressure comes up fast enough while cranking that the sensor is satisfied before there's power to trigger the alarm, or the circuitry is smart enough to delay a bit. The windings that power the CDI (capacative discharge ignition) module are independent of windings that charge the battery. To convince myself there was an alarm and that it worked, I measured the resistance of the oil pressure switch (to ground) with the engine not running to be 230 ohms. I then ran the engine, connected a 230 ohm resistor from the sensor lead to ground, and the alarm sounded. Further, the alarm latches. That is, once triggered, it continues to sound until the engine is stopped. Both the low oil pressure switch and the over-temperature switch connect to the CDI module. An ouput of the CDI connects to the wiring harness which leads to the alarm inside the console on my boat. I haven't tried to simulate an overtemp condition, but I feel more confident knowing the alarm is present and sounds off. This may not help newt with his question that started this thread, but it may be useful to some. Paul in Vermont - where there's 18"+ of ice at the launch ramp.
captbone	posted 03-10-2003 08:21 PM ET (US) I dont know if your motor has a system similar to OMC's S.L.O.W which brings the RPMs down and the engine starts to shake. If you do have a system like this then no worries. I used to run a 140 Rude with no guages or horns and I never worried. When it got a little hot it would slow down automaticly and shake like an sob. When it cooled down it would let you throttle back up. And this was a 1990 motor. IF you have a system like this then you will be fine(you should have it) for more protection also consider adding a water pressure guage.
triblet	posted 03-11-2003 10:46 AM ET (US) My '96ish OMC SLOW won't let you throttle back up until the engine cools off, AND you shut it down and restart it. Chuck
skred	posted 03-11-2003 03:57 PM ET (US) No reply for Merc yet, but at the dealer's yesterday, he said they don't "post" (power on self test) the beeper any more. To test this, we turned on the ignition of a new 2002 60 hp, and - no beeps. Then a 90: no beeps. He says Merc is satisfied with their electronic sensing system that automatically cuts throttle, etc if any system goes out of operational parameters.
lewain	posted 03-11-2003 07:08 PM ET (US) Under Cowling at back of engine you will see a wire that goes into your head between the cylinders, there is a joint in the wire that will seprate. Pull the wires apart turn on ignition and stick a small screwdiver in the connection point and then ground to head alarm should sound if working
Clark Roberts	posted 03-12-2003 07:49 AM ET (US) Seems as though it would be easy to just install a buzzer "test" switch (momentary push type)on console... just a simple grounding circuit of the overtemp sensor... hummm???? I may just do that since I tend to go overboard (no pun intended) on everything else! Happy Whalin'... Clark ... Spruce Creek Navy