2005 Honda City Dear Sir 1300 Vtec There Noise Coming Fi Engine Nor

dear sir: I have a problem with my 2005 honda city 1300 vtec, there is a noise i dont know where it is coming. fi it is from the engine nor the transmission or in water pump or in alternator We done some checking, first we take out the pan belt in the alternator then start the engine but the noise still there, 2nd the mechanic suspected that the sound is coming from the transmission then they bring it down, change all parts inside it but the noise still there and having some jerking when the car is start to move. can you help me finding the solution with my car? thanks a lot if you give me some advice to do. God bless you.