[Trig]

Hi

I was wondering if any of you might be able to help me with a problem I had with my turbo diesel the other morning. When I stop the car engine after short runs in very cold weather there is quite a loud whiring noise coming from underneath the main cabin area. Sounds like a jet engine winding down. The car has always done this and since everything seemed to work ok I ignored it! But on Monday morning clouds of black smoke accompanied the noise. We thought the car was on fire! Looking at my Haynes manual I am pretty sure the smoke was coming from the 'Booster Heater Silencer' whatever that is?? It hasn't happened again but maybe that is because it is'nt cold enough.
Any ideas?