# How Hot ?



## Guest (Sep 14, 2018)

It should have a thermostat and be running somewhere around 160-180 degrees. I can usually hold my hand on a up to temp outboard a few seconds before removing. If you think your having temp issues though this is not the best way to diagnose! Get an infrared temp gun and check the temp in multiple places on the head.


----------



## m32825 (Jun 29, 2018)

If I was going to mount a temperature sensor, where is the best place?


----------



## Guest (Sep 14, 2018)

What motor? Can you get a pic of the head? Aftermarket gauge? Some motors have a spot on the head, some don’t. Typically the “best” place is top end of cyl head but that can change too.


----------



## Smackdaddy53 (Dec 31, 2012)

There are crayons that you can mark stripes on various parts of the motor and they will change color if the temperature reaches the specified temperature. If you don’t have a factory hole to mount a temperature sensor you have to make sure you drill and tap the head in the right place or your readings will not be accurate. Before or after the thermostat is vital. After the thermostat is where I think my Merc 90 had the hole I drilled and tapped for the sensor.


----------



## noeettica (Sep 23, 2007)

I should have a thermocouple that replaces a spark plug washer

I do have an infrared just gotta find it 

what would be the max temp ?


----------



## Guest (Sep 14, 2018)

Again, what motor? I’d guess max of a carbed 2pop to be 180 but I don’t like to guess and give that info so tell us what year and model please.


----------



## Smackdaddy53 (Dec 31, 2012)

Depends on the motor. Most operating temperatures are around 148 if I remember correctly and 180 sounds about right for an average max temperature. You should get a manual for your motor, they are handy if you like to do your own wrenching.


----------



## noeettica (Sep 23, 2007)

Tohatsu 9.9 2 stroke ... I think it is rebuilt ! very quiet and smooth ... So now I will follow a break in procedure ...

I had it over propped and lugged it ... I think it is fine compression is awesome !


----------

