Ford Repair: Engine noise, valve lifter, speed tranny

Question
Chris,
I have a 97 f-150 V6 4,2 litre engine.It has102,000 miles on it.Ran perfect.Started hearing a loud rapping noise,not a lifter sound.Disconnected the serpentine belt.Still makes noise.When i disconnect the coil wire and crank it,I don't seem to hear the noise,possibly because it's not turning over fast enough.I think it's in the top end.Any suggestions as to where to look.Sounds like a squirrel is stuck in the fan type noise.5 speed tranny/Makes noise when clutch is in or out.Any suggestions?Would my ford dealer be able to pin point the problem withe the OBD?Thank you Mike

Answer
hey there. engine noises will not be able to be picked up with a scanner, they only do electrical issues, there are a few things this could be, an experienced technician will be able to distinguish this noise just by listening to it. but the first two things i would look for that are common on this engine is a broken valve spring, or a bad valve lifter, both of these two can give you a ad wrapping noise in the top end of the engine,
Chris