Warning Siren

[tablerockboater]

This is concerning an 18' 1997 Godfrey Sweetwater pontoon with a '97 50 HP Merc that we use to putt around the creeks, canals and bay in SW FL. (We have seen a lot of dolphins and a manatee the last week.) Fun!!! :encouragement:

Everything about the boat and engine seems to work in every way . . . except . . .

When we get to the ICW, and I give it some throttle (never quite WOT), after a few minutes there is a very faint warning siren noise seeming to come from the area of the throttle control. Yes, I am familiar with the warning siren, what it normally means, but this one is very faint. The engine is peeing fine, much better than I do any more.

When we get out of the ICW, and begin idling in the channel back to the creek, the noise stops.

Is there such a thing as a faint warning siren, maybe that means something other than overheating?

 

[gm280]

I personal have no idea not knowing about your particular engine and controls first hand. Are you absolutely sure it isn't some type wind noise mimicking a siren effect?

 

[Texasmark]

Do you ever hear your horn at full blast? If no then you could have a problem and the horn is not sounding shrill as it could have corroded contacts somewhere in the wiring harness providing power to it or it could be defective due to weather also.

Steelspike or Silvertip will probably see this and jump in but a couple of things to think about in the interim.

Just because you have a strong tell tale doesn't necessarily mean the powerhead is being cooled properly. If the tell tale is plumbed off the exhaust manifold cooling water jacket it gets cooling water as long as the engine is running. Pull the cowl and look at the left (Port) rear of the powerhead. If you have a hose connected to the big plate there or adjacent to it and the tube from it goes to the tell tale port then you have as I mentioned.

The powerhead proper is temperature controlled by a thermostat up to 2500 rpms (if like my larger engine) and a water pressure activated "pop off" valve above that. If your thermostat is working properly but your pop off valve is stuck shut, your engine could be overheating when you say you hear the horn which is located inside, or in the wiring harness usually adjacent to your control.

A quick test to answer the pop off question is when you get into the ICW and do as you do and get the weak horn, cut your rpms to idle for several minutes, giving time for temps to stabilize. I would expect the horn to go off. Then accelerate again and see if it returns. If so, you need to replace your pop off and might as well your thermostat while you are right there as they are located under the same cover on some engines.

HTH,
Mark

 

[tablerockboater]

OK. Makes sense. Thanks.

GM280: We considered that it might be a wind whistle, or a vibration noise, so the last time we were out, and it started, I cut to idle and DW and I both used our ears and we both ended up at the controls.

We don't run in the ICW very far.

 

[Texasmark]

OK.

We don't run in the ICW very far.

Personal opinion: If it were mine, I would take a test drive to verify what I said to be fact or fiction. Never know when you will need WOT for an extended time and certainly don't want your engine overheated.........case comes to mind: Outrunning squalls in an open boat. Happened numerous times fishing coastal waters in the summer.

 

[tablerockboater]

Personal opinion: If it were mine, I would take a test drive to verify what I said to be fact or fiction. Never know when you will need WOT for an extended time and certainly don't want your engine overheated.........case comes to mind: Outrunning squalls in an open boat. Happened numerous times fishing coastal waters in the summer.

We went out to look at dolphins the other day and it repeated what I reporedt. We went fast for about five minutes and the very faint siren started (yeah, almost like a wind noise). I cut the throttle back and the siren stopped.