Hi guys,

I have an alarm sounding in the boat after installing a 502 MAG MPI. It beeps like every 5 seconds on idle, and running over 3000 RPM it beeps continously. I checked the drive oil which is full, and the tank and sender unit worked last season with the other engine. The oil pressure is fine, and the temp on the gauge is normal.

I had a temp issue, with a broken sea water pump housing, and an impeller that was basically smashed to pieces.

Both risers are cold and nice at idle, but I feel that the right riser is too hot after driving the boat on the lake for a couple of minutes. I can barely hold my hand on the riser, while the left one is cold and nice.

I back flushed the intake hose from the thermostat housing and back, but couldnt find any debris in there.

So my question is where to start and look for the cause for overheating? And, could the alarm be triggered because the right side of the engine is hotter than the left side? Are there separate sending units?

Please let me know your thoughts.



Regards,

Johan

you need to check the entire raw water path one of the coolers or water passages might be blocked or partially blocked with impeller debris.

I may be wrong but, I thought the only time the alarm goes off is if there is 0 oil pressure or 0 drive oil.

I have had it before (alarm) when I washed down #8 cylinder with gas from broken diaphragm in the VST and made my oil into gas! No oil pressure at idle.

Double checking wiring/connections on the oil pressure sensor and or replacing the sensor is where I would start.

You will get an alarm if it overheats....

check your oil and power steering coolers for debris (impeller, mud, rocks, etc). I'd suggest removing them so you can see through each capillary. An old boat of mine looked like this.....

[ATTACH=CONFIG]501116[/ATTACH]

http://media.channelblade.com/EProWe...ng%20horns.pdf

The high water temp sender is located in the intake manifold near the Tstat and has a tan wire with blue stripe.

Thanks guys! That warning horn lost was great! After flushing my manifolds free from punds of grey stuff it runs cool again....

So, now I know for certain that the warning is from sensor fault. My question now is which sensors that are connected to the warning horn? I have figured out there are water temp and oil pressure sensors.

Also, I have a non-op IAC, new is on its way. Could that trigger the warning horn?

Any thoughts would be very appreciated.


Regards,

Johan

I know the IAC alarm on the 496 sounds like what you have described. Friend as the 496 HOs and the IAC have failed on him several times and the alarm is a beep at low speeds and can turn into a solid tone at higher RMPs.