I can see the difficulty of identifying a noise by description but Iwould be grateful if anybody could help me identify it. On some occasions, after turning off the engine there is a low purring whirring type of noise from the nearside under bonnet area. This can be heard in the cab quite clearly but is less distinct outside. If the ignition is turned on the noise stops immediately. It sounds like a fan or pump. This runs for some time (minutes) but can be stopped by turning the ignition on! Any ideas? TonyP