Temperature Gauge Accuracy

[kwoolard]

I was wondering how accurate are marine temperature gauges? The temp gauge that I have has a range from 120-240 degree F. It has number increments at 120, 180 and 240 with one tick mark between the 120 and 180 and one between the 180 and 240. I am assuming that the tick marks are 30 degree increments. While running the boat this weekend I noticed that my temp was staying just below the second tick mark, which should be 150. Therefore, according to the gauge it was running say 140. My infrared temp gun read 162 at the temp sender and around the thermostat housing, which has a 160 degree thermostat. Can these gauges be that far off or are the increments on my gauge not necessarily 30 degrees? I used a teflon paste instead of teflon tape on the sender fitting when installing, would that have an effect on it as well?

Thanks
Keith

 

[Silvertip]

Re: Temperature Gauge Accuracy

The gauge gets it's ground the shell of the temp sender so it is possible you created a little resistance but I really doubt thats an issue. There are three variables in the temp system. First is the sender itself. These are not high-precision components and amount to a variable resistor that changes its resistance based on it[s temperature. You observed a little over 10% error and that does not include any error caused by the IR gun. The second variable is the gauge itself. The third is the electrical system voltage. In my view, your readings, although rather far from accurate, are not unusual. You now know what the temp really is. Figure the percentage of error and just tack it onto whatever the gauge says.

 

[JustJason]

Re: Temperature Gauge Accuracy

clean the teflon out of the hole and off of the threads... use a tap or a gun brush to get the hole all nice and shiny and recheck it....
Betcha it'll be a lot more accurate!!

 

[kwoolard]

Re: Temperature Gauge Accuracy

Could I check to see if it is a ground issue by running a good known ground wire to the shell of the temp sender temporarily to see if the gauge becomes more accurate?

 

[Silvertip]

Re: Temperature Gauge Accuracy

Yes -- but I will bet you notice no difference.

 

[JustJason]

Re: Temperature Gauge Accuracy

Could I check to see if it is a ground issue by running a good known ground wire to the shell of the temp sender temporarily to see if the gauge becomes more accurate?

the real ground is where the threads meet the block.... clean em up