Heys guys so I been having a major coolant leak with my 06 xjr, it seems to have been loosing a large amount of coolant pretty fast when the pressure is built. My question is can i run water throughout the car until i pinpoint a leak or will it overheat?

also i noticed it leaking from the expansion tank area i took off the tank and it was fine i now suspect the lower expansion hose is that a culprit as well?

06 xjr supercharged 60k

 

Those tanks are know to split open, maybe check it for hairline cracks.

 

I ran into the same problem a couple of weeks ago.
My poor diagnosis I replaced the water pump, when it was the expansion hose PN: AJ811771. Mine hit 82k and seals and rubber are shows its age..
Trans cooler lines are leaking now. That's how they get you to buy a newer model.