Not to drag this out or anyhting - the first post mentioned "diagnosed the issue as the O Rings being fine and just the heater core needing to be replaced.". Are the O-rings the problem or is it the heater core? I think this thread jumped from heater core to O-rings as they both fail on most rovers within
6-10 years(ish).

 

if you leakiong coolant on the floor broad then it is the heater o-ring