Engine Noise

Hi,

My car has been making a noise in the engine for some time now and I have been trying to investigate what the problem is. When the engine is warm, and the car is stationary with engine running, there seems to be a noise coming from the engine which sounds like a tractor/diesel sound. I took it to the garage near work and they said its the water pump bearing and they replaced this which cost me £133.99. After a week later I took my car to a mechanic as I was advised to do a engine flush. This was done and a new oil filter was done. This noise still seems to be the problem. There is no engine management light coming on or any other fault. I have been advised that it could be a timing chain issue or a fan belt/cam belt/tensioners/tappets/pulleys. Not sure which one, but I have been told aswell that the timing chain shouldnt need replacing until it reach 100,000 mileage. Could you please help with any information?

Kind Regards,

Nikki07