ok having fitted a new alternator my girlfriend asked me to solve the next problem..... when the car is parked up after a long drive about 30-40mins and the engine is switched off it makes a nocking noise like somebody is kicking a football against the car any idea what it could be?

Mine makes a ticking noise when I turn it off, but I'm guessing that's normal.

Do you mean it continues to run a bit after shut off? If so, I think I read somewhere that it could be due to a dirty intake manifold.

It sure shouldn't run after the ignition is turned off. If it runs, even for a little bit after its turned off, you had better start looking for glowing carbon deposits in the combustion chamber.

But this noise. When exactly does it happen? Like right after its switched off or 5 minutes after? If it sits there clicking, its just the metal in the exhaust system contracting from cooling.

I dont know if mine makes the same noise as yours, when i turn the engine off there is a knocking / banging noise - not very loud but a noise all the same. It sounds like its coming from the rear, it sounds like perhaps the rear shock is sticking and then expanding but in kind of jerky movements - if that makes sense...........

Ok are you saying that this is coming from the rear of the vehicle or the rear of the engine? Some ticking is normal from the engine during it's cooling but from the rear suspension when the car is stopped.....that's a new one in my books.