Have had a noise issue on my 4 litre Mountaineer. This is an 04 model with 104k on it. It has had regular 3k oil changes and not been worked hard. Started about 2 months ago. Can hear from cabin, outside, and from under vehicle, mainly where engine/trans come together. Noise mainly when idleing in park, but does progress with acceleration (in park). It is not noticable at start-up during high idle. Goes away when shifted into gear, and reappears when returned to park.
It reminds you of a large, low rpm air compressor, (wup, wup, wup). It is not real loud, just noticable. This noise has not gotten progressively louder with time.
Had it to my favorite tranny shop today. He had never heard this one before. Suggested a possible bearing failure in trans but didn't think it was likely. he did some checkin and a Ford tech told him it could be a tensioner on cam belts.
Has anyone experienced anything of this nature?

 

Does it sound like it could be coming from the transfer case ? I would hope a trans shop would have known the answer to that, but you never know.