P38 Heater O-ring replacement

[02RhinoRange]

Hey guys, I've just come across the dreaded heater matrix O-ring leak in my '02 P38.
It must be a slow one, because I can't smell the coolant mixture at all.
I was cleaning out the Rangie last night and noticed the passenger side floorboard was damp. Upon applying pressure my hand became damp wet and slick, and lightly smelled of coolant. Upon referencing data on RangeRovers.net, I've come to the conclusion that it's probably the O-rings that need replacing. This is a semi-common problem, although I haven't heard of many '00+ models needing this repair so soon. It's mostly been pre 2000 models that have been posting problems.

http://www.rangerovers.net/repairdet...ateroring.html <<<----- info

Worst case is my heater matrix is bad. Let's knock on wood, it's just O-rings.

My question is:
Does anyone here have advice or some tips on how to go throught this process?
I've been told the engine coolant runs through the matrix, so do I need to drain the radiator? Should I do a simple coolant flush? Water hose running into radiator while the engine's running for a few?

[Rovin4life]

you dont really need the drain the radiator. Just pull off the hoses to the core.

but remember you are putting air into the system. Pull the upper hose and fill the engine till its filled.

[02RhinoRange]

Well ok, for those that are interested, I hate to dissapoint but I wound up leaving the job to a knowledgable LR Tech.
I went to buy the O-rings from the stealership, and wound up talking to a couple of my LR tech buddies there. They were all kinda cut'n small jokes and telling me "good luck" and other smart as remarks. But so my buddy said the trim/interior Tech may wanna do it on the side if he has time. We checked into it, and he wound up doing it in an hour and half for only $120!
It's normally like a $350-$400 service so I was happy and so was he putting $120 in his pocket. It was a win/win situation.
And about the whole coolant flushing thing, I was told leave the engine off, drain the radiator, then just let a hose run cool water through the radiator, then take off the "to the engine" coolant hose and let cool water run through there. Use "non-premixed" antifreeze and add more water accordingly.