So I replaced the upper and lower rad hoses, the heater control valve, the heater hoses, and the radiator within the last year.

Now I have a coolant leak. It appears to be coming from where the lower rad hose seats. Its weird because the hose is clamped on pretty tight and the hoses still have pressure in them after the engine is turned off. What's going on?!

 

If the rad is old or the original, it's likely the rad itself is leaking. From my experience owning 4 XJs from 1996 to 1998 models, the rads deteriorate. I replaced rads in 3 of the 4. You could try some Bars Leaks for a stop gap measure temporarily, but I'd recommend replacing it. The procedure for replacing rads is pretty straightforward and not difficult at all. 1-800-RADIATOR is a good low price source for them.

 

The radiator, all the hoses, and even the heater control valve were replaced within the last year. Everything is pretty much new lol.


I found the problem shortly after posting this. The original water pump was leaking a little (seals were gettin bad). I replaced it with a new all aluminum one and it looks like it's all fixed.