115 yamaha over heating

[six flynns]

I have a 1995 115 Yamaha that over heats when you are running at about 4500 RPM's. If you back it down and pump the ball the alarm turns off and you can go about your way. But then after awile it occurs again, I have replaced the water pump, thermostats,temp sensors in head,rebuilt carbs and removed exaust cover and cleaned carbon from ports. Replaced fuel pump and checked flows and they were all within specs. Can anybody help?

 

[Boatnthedesert]

Re: 115 yamaha over heating

The alarm also indicates oil level on two cycles. Also on later models it will indicate whether to have water in your fuel. If yours is a two cycle I would start at the remote oil tank generally the tank sensor or the wiring to the motor is the culprit.

 

[DocBarclay]

Re: 115 yamaha over heating

Hi, i have a late 80's yamaha 2 stroke 115hp v4 (aeto) motor which is overheating (alarm goes off) at around 4500 revs or higher, i stop and leave it running for a minute or so till the alarm stops and keep on going untill it happens again shortly after.Could this be an oil deficiency problem or scale build up in the heads insulating them from cooling properly? cheers,

 

[scottfromoz]

Re: 115 yamaha over heating

My 93 115 did the same thing. They have tight water galleys. If you have tried the usual water pump, thermostats poppet valve etc stuff then pull head covers and you will likely see some little holes that return water about the width of a match head that will have scale in them. Clean them all up including the rest of the area...that cured mine nicely. I didnt do the exhaust but that is an area to look at if the above does not work.

Cheers