Ok, i just installed a koyo n i believe there's a slight leak on my temp sensor guage attached to the bottom of the radiator. I used vice grips to loosen it originally since i didn't have the right size socket or crescent wrench, but i will try to tighten it this time without taking the radiator out of the car, maybe just the fan. I've searched online and also on s2ki but no luck in finding what the size is.. thanks for the help!

and on yea, did you put teflon tape on the sensor when you took out yours?

 

put the teflon tape on, the sensor is most likely either a 19mm or 17mm.

 

Oh, I remember that happening. it was a PITa. I think I pulled the radiator stays off, lifted the radiator a few inches off the ground and then tightened it.