Engine Alarm

[Splash]

I have a 502 in my 26ZX and last fall when I had an Exhaust valve stick the temperature went pretty high with no alarm sounding. By the time I felt the spudder and looked down the temperature was up around 220, when I restarted it the temp. showed almost 240 but dropped imediately once the water started to circulate. My old donzi's either cherped when you turned the key to the on position or would go off if you left it in the on position for more then 10 seconds. This boat does none of the above so if someone could tell me if any of the above happens with the 502 (year is 2000) it will make it a bit easier for me to track down the problem. I hope its just a wire that fell off the alarm speaker which I think is located under the dash.

Thanks Jim

[Splash]

Can anyone confirm if the Alarm buzzers goes off if they put the key in the on position on a Mercruiser 502 ?

Maybe a shorter question will work better :)

I'm going to work on the boat this weekend and plan on taking a look at the buzzer and testing it.

[Pismo]

Yes.

[pmreed]

Mine didn't until I had it installed/fixed. Does now.

Phil

22 Classic 502

[blackhawk]

The alarm buzzer should be hooked to a "piggyback" on the backside of the key switch. Mine was a purple wire if I remember correctly. However, the cutoffs should still work limiting rpm even if the buzzer isn't hooked up.

[Splash]

Thanks Guys, I hope its just a wire that fell off or a bad buzzer. Really wouldn't mind putting a light on the dash as well but will take the buzzer for now.

Jim

[Splash]

I have never hit the rev limiter but I can tell you I get no audio at all on
the alarm, normally you get a chirp or a solid tone once the key has been left on.

Thanks Again, Jim

[fasttrucker]

I dont have a rev-limiter on my custom motor but when my bravo-1 top came loose my alarm went off.The oil level dropped.sure glad it did go off!Was able to get it fixed with out burning up my outdrive.

[Splash]

So I replaced the buzzer and it now works, thats the good news. The bad news is when I put the key in the on position it beeps twice and I get a very soft constant alarm. It almost sounds like a have a partial ground which is causing the alarm to come on partially. I then started it and the faint alarm stays on, I figured if I go to the three sensors, Low Stern oil, Temp and Oil and disconnect them one by one maybe that would tell me which one is partially grounding out.

Does anyone know what 2 beeps on a 502 means, I'm not sure its it related to when the engine overheated last fall. The boat runs great on a hose but I haven't taken it out for a sea trial.

Hopefully two beeps is standard, my other donzi's always gave a quick chirp
when you turn the key on. I also think this is why the buzzered was dead from the constant tone.

Thanks Jim
PS. I did mount the Oil Reservoir on the transom, does it need to be grounded ?

[Splash]

Forgot to mention that I don't get any beeps once the boat is running,
just happens when I first turn the key in the on position.

Thanks Jim

[fasttrucker]

I get a loud buzzing when I turn the key on.Start motor goes off.Sorry I cant Say anything that might help.

[Splash]

Thanks for the response. Can anyone confirm where the Oil Audio Alarm Sensor is located on the 502 motor. One diagram I have shows it to be a two lead sensor and the other diagram shows it to be a one post sensor with a Blue/Tan wire connected to it. I believe this sensor is located back by the distributor on the block, the oil sensor for the guage is down by the remote oil filter (starboard side down by where the oil pan meets the block).

I have disconnected all the sensors and I still get a faint alarm sound. I did speak to Floyd Bell who is the manufacturer of the buzzer and they said its common to get a little bit of leakage and to simply put a 2 watt 470 ohm shunt across the buzzer. I'm going to take a ohm meter to it this weekend to see if I'm getting a partial ground somewhere but otherwise I will try the
shunt resistor.

This is such a pain because the alarm did not work when I purchased the boat and now that I had the heads reworked I'm not sure if its just a bad
sensor or maybe a wire partially grounded or pinched.


Thanks Jim

[Morgan's Cloud]

Jim ,

I was made to understand that when you switch the ignition on (502 MPI)
you hear 2 beeps and hear the fuel pump prime and then stop.
At least that's what mine does .....(or did when I last ran it eons ago :bawling: )

Steve

[Splash]

Thanks Steve,
I get the two beeps with the pump as well. I really think everything is OK
but this buzzer keeps a quarter volume continuous tone (I think this is why the buzzered originally went bad. With the boat running in the driveway I can barely here the tone but still want to get it addressed.

Since I unplugged all three sensors and it still toned it must be leakage or getting a partial ground in the harness.


Jim