Put the beer down Slick and get your reading goggles on!

OP has already said the following : I've had the thermostat, pipes, water pump, belts, rocker gaskets,
replaced recently.was also smoke tested.

Clue's in the words..

Ben, I've just changed the rad on mine, fairly easy, just time consuming due to unbolting everything and disconnecting hoses etc.. Approx 2-3 hours total time.

Also, you might want to get one of these: eBay Australia: Buy new & used fashion, electronics & home d to get the viscous fan off to get the shroud out to get the rad out.. and breathe. Or make one yourself. Personally for the sake of a few quid I bought this and it did the trick nicely.

Edit: Oh, and you'll need to replace the heat exchanger X rings-2off. No.12 here: RealOEM.com * BMW E53 X5 4.4i Oil-cooler pipe/heat exchanger

Ian

__________________
Present:
01 X5 4.4i
07 Yam R1

Past:
89 R32 Skyline various mods, running 442 BHP
00 Merc CLK55 AMG
01 E39 M5 Haywood and Scott silencers
02 E46 M3 Supersprint Cats, Eibach Lowered, Thorney Motorsport Remap, running 368 BHP