I have a 1997 civic - runs great, rides great, but about half the time I drive it, the temp guage reads hot (almost to the red indicator). I replaced the t-stat, but that didn't help.
Could it just be the guage? Does the radiator need replaced?

Make sure your radiator fan comes on when it gets hot, if not, it's
probably just the temp switch that controls the fan.
But also it could be the fan itself.
You can hot wire it to check it.:smokin:

check for air in the system. do a flush, change the coolant, and do what jclark said