Yamaha 70HP TLRS (BETO in New Zealand) alarm going off

Hi there. First time user of a forum here. I have a question.

I have a 1994 70HP Yamaha that I rebuilt 12 months ago. It has done about 45 hours since rebuild and has been fine. Yesterday I took it out and after 5 mins of running in the 5 knot limit the alarm came on. Rooster tail putting out plenty of water and oil was full etc. Lifted motor to check intakes etc, all clear. Put motor back down and immediately with ignition on, the alarm sounded again. Very close to ramp so turned around and started heading back to ramp. 10 secs later it stopped? Carried on back to ramp and checked the obvious things again. Oil, sensor wires, intakes, and motor didn't feel overly hot but not really easy to tell as at 5am in the morning, everything seems warm!

Went out for the day cautiously and motored around on and off for 5 hours between idle and WOT. No more problems? Haven't had issues like this in the 3 years I've owned it. Could it be moisture in the remote box or a bad connection? How much water should it be pumping? It's a fairly thick decent stream of water that comes out.

Any clues?
Cheers, Pete

Re: Yamaha 70HP TLRS (BETO in New Zealand) alarm going off

You could have had some blockage of water inlet and when you lifted motor it cleared it but took a small amount of time to cool motor back down .
maybe your PRV was stuck open or thermostat stuck closed and then started functioning properly.
When was the last time you serviced them?

Also could have oil level switch malfunctioning.
Hard to say if it is not doing it anymore

what caused the motor to be rebuilt last time?

Re: Yamaha 70HP TLRS (BETO in New Zealand) alarm going off

Thanks for the quick response 99yam40. The thermostat was replaced when motor was rebuilt. It was rebuilt due to throwing a thrust bearing in the crank after it was starved of oil as the little white plastic clip connecting the stainless steel arm to the oil pump broke! Luckily it didn't damage the engine and was shut off immediately. Still did the rebuild of power head regardless. New rings, bearings etc, and wanted to replace the shift shaft rod which is a design fault in those motors in my opinion. Should have always been stainless.

Checked oil level after flushing motor and it had used oil as it should have. As a separate question, what temp should the water spout be at? Should it be cold at idle and then warm once the thermostat opens presumably? It's always cold when flushing and I've never checked it out on the water after it has been running normally.

Yeah, I'm hoping that it was just a loose connection or sticky thermostat. Strange that it just stopped and didn't re-occur again? I believe that the impeller was changed prior to me buying the boat. I have never replaced it as it pumps water really well. Should I need to?

Re: Yamaha 70HP TLRS (BETO in New Zealand) alarm going off

Even when the clip breaks or linkage comes loose I was under the understanding it would go to WOT oiling not reduce the amount of oil and cause problems.

My C40 indicator stream just gets warm never hot

Yes I would replace the water pump every year or two as they recommend depending on where and how it is run.