temp sensor on a 74 evinrude 115HP model 115493b?

[kevinr]

Question - does this motor have a temp sensor? I added a gauge so i need a signal. i'm assuming i cant use the wire going to the overheat buzzer - guessing it only has signal above a certain temp.

if it has a sensor, what am I looking for? I need to provide signal to my gauge. If it doesn't have a sensor, I'm assuming I can add one in a blind hole in the head.  Because it wont thread in, can i use some JB Weld or something similar?

Thanks. Kevin

[Capt. Bob]

I believe we have been down this road before.

https://classicaquasport.com/smf/index.php?topic=15482.msg151215#msg151215

Please review this link.
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1974&hp=115&model=115ETL74B&manufacturer=Johnson&section=Cylinder+And+Crankcase

I'm not sure what model 115 you have but it appears they are all the same. Look for part #47. That this the thermo switch that trips the overheat alarm. Again, that occurs when the switch reaches a certain temp and completes the circuit to ground. Look for this switch on top of the motor just behind the lifting ring.
I would leave that sensor in place so the horn/alarm will work.

You may have a blind threaded hole as shown in this video. It is for a 70hp not a 115 but the method is the same. You may also find the "Z" bracket mentioned in the vid for mounting to the head or fab one yourself.
https://www.youtube.com/watch?v=DRmF_7fJpkg

The video describes where you can locate the sensor. I guess you could JB weld it in the hole as long as it makes positive contact with the head. You will need to test the sensor you purchase with the gauge you now have to insure the gauge readings are "in the ballpark". Wiring the gauge and placing the sensor tip in hot water of a known temp before install would be pretty accurate I'd think.

Good luck.