It sounds like the fan hitting the shroud, but it is definitely not. Actually sounds much like holding a playing card in a bicycle wheel as it spins. Only occurs at the very end of braking (just before stop) and at initial acceleration from stop. Sound stops after a few moments at dead stop or after hitting about 1500 rpm. I can sometimes cause it to happen while sitting still and have traced the origin to the front of the engine, under the engine cover and apparently inside the cover that I think covers the timing gear (front of engine under valve cover). I will take it in for inspection, but can't for a few days. Any ideas or cause and consequences of driving. Engine runs perfectly, otherwise. Thanks!