g4wam

I agree with David that the HGF scenario is as he describes for an F or a TF , interestingly the gaps between HGF failure's on early MGF,s were about 20000miles .On early TF,s the period was longer around 50000 miles, t he good news is that the problem is getting rarer as newer style components are fitted. If the car is driven after a cooling system event and all the coolant has been lost there is probably no other outcome other than HGF. The coolant tank tops do let go on there own and clouds of steam exit and if it happens when stationary then the situation can be recovered , but driving on only ends in tears.
Regarding repairs to K series HGF or even just cam belt changes I only trust the ex ROVER mobile guys , they have a vested interest in getting the job done properly.
The above comments are purely mine
regrds

Mike