Not a silly question at all. At first I noticed a "puff" of what looked like steam comming out from under the bonnet. I put some "radweld" in the radiator to see if it would fix the leak. I left the car running for half an hour as directed by the "radweld" and it did seal the leak.
It was only when I drive the car that it started to leak again. I guess it was the additional pressure build up from the system. The leak is right at the top of the radiator in the middle. I am not an expert but I am not aware of any hoses running through this location?
I will try and do some more investigative work and possibly remove the radiator at the weekend to identify exactly where the leak is before I go and purchase a new radiator. In a way I am sort of hoping that it is a leak from something else like a fitting or a pipe as this will be easier to rectify.
E90 318i 2007 N46 2.0 Manual
E53 X5 2004 M54 3.0 Sport Auto
E83 X3 2004 M54 2.5 Auto
Last edited by white_lancer; 11-20-2012 at 04:02 AM.