test overheat alarm???

[tarpon]

I have a Merc 2001 90HP ELPT 4 stroke. A year ago the engine overheated and the alarm did not sound. Since then I had the impeller, thermostat and a few other parts replaced. Now, I'm having problems with the water pressure gauge not registering but the engine is 'peeing'. So far so could. But, I don't want to have the engine overheat on me again so....<br /><br />Does anyone know how I can test the alarm to make sure it is in proper working order?<br /><br />Thanks

 

[Jerry M.]

Re: test overheat alarm???

I believe the alarm works on impedence. The warmer the engine, the higher the impedence on the wire from the engine to the alarm. If it gets too high,(maybe +170) the alarm sounds. Try this: find the tan wire coming from inside the engine which should be connected to the sender inside the engine. If there is a quick connect between there and the controls on your console, disconnect and ground the wire going to the alarm. Do this with the ignition on, but the motor not running. This will simulate an over heated engine. It will at least tell you there is a complete circuit. From your last experience, maybe the sender is malfunctioning.<br /><br />Jerry

 

[dilligafda]

Re: test overheat alarm???

Gone Fishin'<br />You are partially correct with the following "I believe the alarm works on impedence. The warmer the engine, the higher the impedence on the wire from the engine to the alarm. If it gets too high,(maybe +170) the alarm sounds."<br /><br />The test for the alarm on this engine should be performed while the engine is running. The alarm system runs through the ECM and will not function unless the engine is running. You can also check it by running the outboard and disconnecting the oil pressure switch. Again, the engine needs to be running to perform these tests. <br /><br />Good Luck!