hi there, i bought an 07 2.2 accord cdti about a month ago, ever since its started this annoying humming noise around the engine, I've replaced the aux belt with the shorter version but its still there, i took the belt back off and its still doing it, so it isnt alternator, power steering pump etc. when its idling the noise can't be heard only when reved. im now starting to think its a timing chain issue but I've read its usually a rattle not a humming noise. maybe the oil pump, water pump? has anyone else came across this problem and fixed it? the car has good service history and I've done an oil change with 0-30. forgot to mention, its definitley not the clutch.