I can't remember why I did this, I think I was curious about the unique K bike noises......... (I'm used to alot of scary clanging and banging, tappity Brit bike noises) Anyhow, I was using a stick, and listening to parts of the engine, and the water pump makes a rumble grinding noise that is probably not so good. :-\ Should I get moving on a replacement now, or is that sort of normal?