'05 Optimax 150 warning horn question

[lotsip]

Just bought a 2005 Optimax 150 saltwater engine and have used for a few hours , engine runs great, however, yesterday I was out for 10 minutes running 5-8 kts.....when i heard the warning horn go off, i immediately slowed to an idle and put it in neutral. The horn went off after 15-20 seconds. There was water coming out of the water pump, and plenty of oil in the remote oil tank, so I kept cruising around for another hour or two with no further warning horns or problems whatsover. No idea why i got the warning horn, any thoughts ?

 

[Texasmark]

Thermostat not opening when it should would be my first guess and the reason would be salt water corrosion....time to pop the cover and have a look or better yet just replace it and a pressure relief valve that may be adjacent to it under the same cover maybe. 2 strokers have a stat set for 143F. The OT alarm is set to 195F. Below 2500 rpms the stat controls engine temp. Above that the water pressure from the pump pushes a bypass valve off it's seat which is much larger than the stat hole and non temp related. This provides additional cooling at higher rpms.

Would expect the 4 stroker to have a similar arrangement for the same reason.....stroke type shouldn't have anything to do with it.

I'm thinking the stat is getting crudded up with corrosion from the salt and was lightly stuck from sitting since your last outing.

 

[lotsip]

Thermostat not opening when it should would be my first guess and the reason would be salt water corrosion....time to pop the cover and have a look or better yet just replace it and a pressure relief valve that may be adjacent to it under the same cover maybe. 2 strokers have a stat set for 143F. The OT alarm is set to 195F. Below 2500 rpms the stat controls engine temp. Above that the water pressure from the pump pushes a bypass valve off it's seat which is much larger than the stat hole and non temp related. This provides additional cooling at higher rpms.

Would expect the 4 stroker to have a similar arrangement for the same reason.....stroke type shouldn't have anything to do with it.

I'm thinking the stat is getting crudded up with corrosion from the salt and was lightly stuck from sitting since your last outing.

I'm not knowledgeable with engines, so, just stopped by the place where i bought the motor/boat. The marine mechanic there told me to take the cover off and make sure the oil tank cap in the engine was snug. I will do that, and if I get that warning horn again, I will tell him what u said here. Thanks so much !

 

[lotsip]

was stripped threads on internal oil tank cap........mechanic tried an aspirin cure, glued cap.....but, didn't work, ..........replaced tank, running like a champ now