I became aware of a clonking noise from the rear of the E430. It sounded like something was clonking against the petrol tank. I found a very-corroded piece of steel small-bore capillary tube. It was not secured and was knocking about. It traced one end of it to a rubber tube connected to a small connector in the centre of the back of the fuel filter. This is on the rear left side of the car From there it trailed across the rear sub-frame to the right side and did not appear to be connected to anything. Looking a bit further, I found a loose red rubber tube connected into the fuel piping to the tank. In the end of the rubber tube was a corroded stub - Which I guess is where the steel tube used to go. It has obviously not done anything useful in a long time. The steel tube is so-corroded that it no longer has hole thru the middle of it. What did it do ? Does it matter ? Is there any point in replacing it ? Thanks for your replies.