Land Rover Repair: over heating, viscous coupling, rover model

Question
I bought a rang rover model 1998 SH.E 4.0 and it started over heat.I have changed the radiator  but still it over heats.I have spent enough so i want to fix it my self now please help.
thanks

Answer
Check the thermostat and water-pump also, either will cause low water flow.  Also the viscous coupling may be bad.  After the engine is up to temp, shut it off and try to turn the fan, if it is stiff the coupling is good, if it spins free the coupling is bad and the fan isn't providing any cooling air.  Check the radiator after you shut it off, it should all be hot, if it's just warm, or cool, you have no flow-either the pump or thermostat are bad.