valve timing marks on engine code AML

i am replacing timing belt on audi a6 AML engine and i need the diagram for timing marks and the procedure for the work. the car has a whining noise problem on engine front and overheating. the noise seems to be coming from idler pulley on belt tensioner . water is not circulating in yhe engine because when it boils the lower radiator hose is cold and the upper hose is too hot so i thought of checking if the water pump impeller collapsed. to do this the timing belt had to be removed.the pump is ok so it could be a faulty thermostat,or what do you think