This happened three times already in the past 2 days. its been very hot here lately (100+), and after a long drive i park the car and let it idle for a minute or so to cool down. Right when i turn it off, from under the hood comes this loud winding down noise, as if turbo is slowing down its rotation, but bearings are not getting enough oil, for the lack of better comparison. The fan stays running for a while which is normal, so that is not the noise i am talking about. Noise that concerns me is much louder and only lasts 3-4 seconds. Anybody heard anything like that? Any ideas are appreciated.