overheating / temp. gauge problem

Hi Everyone,
                    Recently bought a 93 accord ex. 183k miles. replaced the alternator belt rotor, t-stat and both sensors for temp. control that is connected to the radiator fans.
I drove 1200  miles in 36 hours and noticed the temp. gauge was approaching the red line. After letting the engine cooled off when I stopped I found I had a slow leak of coolant with a faulty seal on the front housing where the coolant enters the engine.
My problem now is the temperature gauge goes right to the red line when the ignition is turned on with the engine cold and not running. I am stumped any help will be really appreciated.
                 Thanks.

you should post this in the general tech area,, more members will help you there.  but anyho
If temp gauge goes to red as soon as you turn the key on, cold engine  ,
possibilities are : bad sending unit.........short to ground ( pinched wire )  wiring from sending unit to gauge .........bad gauge ,,,

I changed the sending unit , also called  engine coolant temperature sensor . That fix the problem . Thanks. I am still trying to learn all the methods of using this sight. Hopefully I get it as time goes.