Measuring coolant temperature

I have a 95 accord 4 cyl with about 170,000 miles. The speedometer
died so i had the instrument cluster replaced. Everything seems fine
but the water temp guage appears to read lower than it used to. I
don't think anything is wrong but I would like to know how to get a
good reading on the coolant temp once the car is at operating
temperature. what's the best way to do that?

 

standard instruments only give dumbed-down readings, so as long as the
needle moves and at normal operating temps, stays in the same position,
you'll be fine.

http://www.flickr.com/photos/38636024@N00/2445120839/

if you're really worried, and you still have the old cluster, each
individual gauge is replaceable, so you can put the old one back in.