I have an RS2000 with the standard I4 2 litre engine.
It has covered just under 82K and there is a funny nosiy that can be heard from inside the car when it is started up and running.

Basically the noise can best be described as similar to water running through a pipe. The expansion bottle is reading the correct level and the car is not overheating.

There is no water or anything left when the car is left standing and I cannot locate any leaks.

I am wondering if it could be air rather than water, and if so where is it likely to be coming from...

Someone pleeeeeeease help.