Only had this car 24 hours and the temperature shot up quickly after an 80 mile journey. The expansion tank shot the lid off as this was the weakest point. I have replaced that but the system is still overheating and water is coming out from somewhere. I need to bleed this of air and try to locate the leak. I`m hoping it is not the rad or water pump and just a hose but if anyone can help me, i would be very grateful. The car is the 1996 E38 steptronic 735i model. Thanks.

It sounds like a block in the radiator. I would remove radiator and flush it out and then get it pressure tested. This is why I think your lid shot off. Once you replace the radiator fill with anti freeze and run the engine as it warms up the thermostat will open and you just continue adding anti freeze until the radiator and engine are full. It is also a good idea to have the heater operating while you do this to ensure the whole system is flushed. Then just top up your reservoir tank and hopefully you will be motoring on :-) all the best