My LR2 has always made a whirring noise after shutdown for a minute or two, always assumed some kind of emissions/evap gadget. Or it could be the radiator fan, many cars will continue to run that after shutdown. So it's probably normal, but as Flybd5 said it cannot be anything belt driven.

 

I think it's a purge valve just between rad fan and front middle of engine near the throttle body ......I believe it's part of or connected to the emission control system. It makes a fine but low pitch hum for about a minute after the vehicle is shut off.

 

Excellent point. The EVAP canister purge valve is indeed located in the engine compartment, under the intake manifold and next to the alternator. The Engine Control Module (ECM) operates the valve to purge fuel vapor from the EVAP canister into the engine for combustion. It can be accessed from underneath fairly easily, though. It is an electrical component, and it can get stuck open or closed. Since you mentioned you R&R'd the radiator, It is also possible that when you replaced the radiator you accidentally disconnected the purge valve and it is unable to do its job. This will cause problems with fuel getting to the engine from the regeneration of the charcoal filter in the EVAP system that absorbs fuel vapors so they don't get released into the environment. The charcoal has limited absorption capacity and needs to be regenerated, and that happens when the engine is running. Pressure in the fuel system may be building up and is unable to release normally, so it may be releasing slowly past the purge valve, hence the whining noise? Stranger things have happened.