yamaha overheat alarm

[Jeffrey McCrave]

I have twin 115 Yamaha 4 strokes. After running for 1/2 hour at 4100 rpm the alarm sounded and engines dropped to 3000rpm. I put them in neutral and the alarm stopped. I revved them up and ran fine for 2 hours (some trolling) then on the ride home the same thing happened ,alarm,neutral, no alarm, ran fine. Any suggestions?

 

[99yam40]

Re: yamaha overheat alarm

What did your gauges have to say about what alarm came in? are you sure it was overheat?
I thought safe mode on a Yamaha was 2000 not 3000, but not sure on those 4 strokes.

If it was truely overheat When was the last time the water pumps and stats were replaced?

 

[Jeffrey McCrave]

Re: yamaha overheat alarm

What did your gauges have to say about what alarm came in? are you sure it was overheat?
I thought safe mode on a Yamaha was 2000 not 3000, but not sure on those 4 strokes.

If it was truely overheat When was the last time the water pumps and stats were replaced?

I am not sure it was overheat a;arm. WHAT OTHER ALARM COULD IT BE?
i WILL TRY TO DUPILCATE THE PROBLEM AND SEE WHAT THE GAUGES SAY.

 

[Bamaman1]

Re: yamaha overheat alarm

First thing to do would be to check the engine oil levels.

When in doubt, change the water pump impellers and the thermostats. Then, try the boat out. Hopefully your problem will be settled.
The cooling system is often overlooked--until they cause a problem. They're just part of normal maintenance.

The impellers are cheap @ $29. Thermostats may be $50 or so--1 per engine. You can get them off the internet.

Be sure to change the lower unit grease while you're at it, paying close attention to the oil that you drain out for contamination.

 

[Jeffrey McCrave]

Re: yamaha overheat alarm

I am grateful for the suggestions but I still can't understand why the alarm stopped in neutral and didn't come back on when I went back to speed.

First thing to do would be to check the engine oil levels.

When in doubt, change the water pump impellers and the thermostats. Then, try the boat out. Hopefully your problem will be settled.
The cooling system is often overlooked--until they cause a problem. They're just part of normal maintenance.

The impellers are cheap @ $29. Thermostats may be $50 or so--1 per engine. You can get them off the internet.

Be sure to change the lower unit grease while you're at it, paying close attention to the oil that you drain out for contamination.

 

[R Socey]

Re: yamaha overheat alarm

Make sure the pee streams are good. My twin 150 2 strokes had an alarm problem - the so called machanic told me
that I must of ran in very shallow water and sucked up mud - that my thermostats were clogged. It turned out to be
an oil alarm.

 

[99yam40]

Re: yamaha overheat alarm

I am grateful for the suggestions but I still can't understand why the alarm stopped in neutral and didn't come back on when I went back to speed.

until you can tell us what the alarm was, we will not have an idea of the reason

 

[yamatech43]

Re: yamaha overheat alarm

Ok, I'll make this much simpler....go to Napa and get yourself some melt sticks(they are available to melt at different temps) and when the alarm sounds, quickly take the temp of the head and see what it is....you don't say the year of the motors, but could be anything from oil pressure too low, bad sensor, temp(or sensor)....get us going the right direction here.

 

[Jeffrey McCrave]

Re: yamaha overheat alarm

Ok, I'll make this much simpler....go to Napa and get yourself some melt sticks(they are available to melt at different temps) and when the alarm sounds, quickly take the temp of the head and see what it is....you don't say the year of the motors, but could be anything from oil pressure too low, bad sensor, temp(or sensor)....get us going the right direction here.

Checked oil OK. Researched down her (virgin Islands) found others had same problem, salt buildup in cooling system. I am going to use a salt away product that you run through the engine. I will let you know if it works.
Thanks
Jeff

 

[99yam40]

Re: yamaha overheat alarm

You never answered the question about when the last cooling maintenance was done. Usually when you pull the stats you will see what condition the cooling passages are getting into.
Being run in salt water and probably never flushing with fresh water will cause more than just salt build up. Corrosion of the passages and the internal anodes will restrict the water flow to the point of the need to pull covers and heads to clean things out hoping the bolts do not break. How old if these motors?