Firstly, where is it leaking from? If its from the gasket seals around the water pump body, you can use rtv sealant to re-seal the water pump.
However, if it leaks from the pulley bearing, I'm afraid you will have to change the entire pump.
Tried to search for threads with regards to the Skyline 250GT but could not find any. Am looking to buy this car but need more info on it. Appreciate if any of you guys can share any info related to this...
I am keen to buy a late model, preferably 1999+ FD half cut (i.e. RS, RZ, spirit R etc) in good condition. If anyone has one available, can source etc please let me know. I may consider others.