91 Evinrude 115 - Starboard temp sensor warning horn

The Starboard o-temp warning sensor goes off after about 5 minutes running on the muffs at idle. ~ 900 RPMs. My OMC manual does not tell you how to get the sensor out. Do I need to order a head gasket and pull the head to get to the sensor and install a new one? I can count about 2 seconds with my finger on the head on each side before it's too hot to hold. Port side is OK. Same temp to the touch, ~ 2 secs.

Thanks,
John

Re: 91 Evinrude 115 - Starboard temp sensor warning horn

I wouldn't second guess the sensor before I verified temp with a hand held temp gun or that the engine block and heads won't melt a 163 degree temp stik .When was the last time the waterpump and T/stats were replaced?And yes,On your engine I believe that the head cover needs to be removed to replace the sensor.This would involve new gaskets and initial as well as a break-in retorque of the bolts.

Re: 91 Evinrude 115 - Starboard temp sensor warning horn

There are also deflectors under the head covers. If they become dislodged, they can cause hot spots.

Re: 91 Evinrude 115 - Starboard temp sensor warning horn

Water pump was 2 weeks ago. The horn was going off prior to the pump change. However, the motor runs for a longer period of time before the horn sounds now. The temp stick I found on the net was about $30 the sensor is $33. That is why I was leaning toward the sensor. If the temp stick says it's OK, I'll have to by the sensor anyway, I'm putting off the T-stats until I have no other choice. They're going to be a pain to change.

I'm looking at the parts diagram. I see the deflector, looks like a small tube inserted into the head. Other then the obvious from the name, what is it's function? How could it get "dislodged"? Looks like I would have to pull the head to get to it? Is this a part that is normally replaced or cleaned and reset?

Thanks,
John

Re: 91 Evinrude 115 - Starboard temp sensor warning horn

The water deflectors basically keep the cooling area around the cylinders full and flowing to assure even cooling around the cylinders. They can, over time, flatten and dislodge short circuiting the water flow around the cylinders. They are usually changed out with a rebuild and not something you would take the head off just to inspect on a regular basis.

Do remember your engine has two t-stats, one for each head, and one can fail while the other continues to function properly. And, yes, they are a big pain to change out especially on a bubble back. Been several threads on the subject and how best to do it.

Just a question, is this a salt water engine?

Re: 91 Evinrude 115 - Starboard temp sensor warning horn

The prior owner had used the motor in salt water. Don't know how much it was used in the salt water or if he flushed it after each trip to the Texas Gulf, one of my concerns. It's a 9 hour drive from the metroplex to the coast so, it wasn't in the salt all of the time. The motor runs good. Unfortunately, the previous owner did not put an hour meter on the motor so, I don't have any idea how much use it has had. I have owned it for 5 years and only run it in fresh water. The previous owner bought the boat new so I am the second owner.

Thanks,
John