Universal M-18 operating temp

[mherrcat]

The M18 in my 30+ runs at less than 160 on the temp gauge. I have installed a new thermostat and new temp sender that I purchased from Featherman before he closed his business, but it still runs the same temp. Any ideas why it does this? I thought the operating temp was supposed to be 180. Does running at this temp pose any problems?

 

[Loren Beach]

Couple of thoughts:
Our M-25XP runs at an indicated 160, and has since we bought the boat in '94. Over 1900 hours now. This did not change after I replaced the thermostat during the the "great coolant hose renewal" project some years ago.

And then, I often wonder just how accurate and calibrated the old temp gauge really is in our panel, anyway. (I have heard of the 180 degree target temp, also.)

That's two thoughts. Time to pause.
:nerd:

LB

 

[treilley]

Get an infrared Thermometer. They are cheap and can verify the accuracy of your gauge.

 

[mherrcat]

So, where would you aim the infrared thermometer to take a reading?

I have tried swapping the old temp sender for the new one and still get the same reading. I thought it might be the thermostat, but it's new also.

 

[treilley]

I would point it at the thermostat housing after the engine has warmed up. That should be the same temp as any circulating coolant.

 

[escapade]

temp woes

I wouldn't get all hung up on the indicated temp as long as it's consistant. There are Sooo many electrical contacts between the sender & gauge that it's a wonder they work at all. The infared temp will answer actual temp value and just use your gauge as a relative indicator (which is it's true function). As long as engine runs good (no excessive smoke or overheating) you should be OK.

 

[mherrcat]

I thought about the wiring contacts also. Since the sender is just a temp sensitive variable resistor, seems like any variations in the circuit could throw it off. To test the gauge I once inserted a control pot that operated in the same resistance range in place of the temp sender in the circuit.