Timing belt tension

Hello community, I’ve been waiting for a 2002 punto 188, 1.2 8V 60 hp. Have recently replaced the timing belt, including the clamping roller and water pump, because I don’t know when the last time was done. Before I did that, I had the old timing belt a bit strained, because I have such a dull ratter in thrust mode, which sounds as if rubber is beating against plastic. The noise is however speed dependent, not speed dependent. Because of the clamping said noise has not disappeared, however, but there was such a kind of metal looping, as soon as the engine gets warm. The noise is heard in idle run and as soon as the engine has gone off when gas is given. So it’s not continuous. Well, I thought that either the WaPu (storage) or the clamping roller will be broken. So then again, I’ve got a little bit of punishment.