New to the forum, hopefully this is the correct area to be posting this. Hoping someone could give me a little help on this. I have a 2008 Fusion that has a rattle from hell when the engine is at an idle and under some sort of load, power steering, A/C, the alternator, whatever. Sound like marbles in a can. It is especially bad when the car is in gear. You can watch the serpentine belt tensioner jump around as it makes this noise, and if you apply some sort of pressure to the tensioner while it it running it stops.
With the belt off everything seems to spin freely. I've already replaced the tensioner (with a Motorcraft one), belt, idler pulleys and the alternator when it gave out. It's been going on for a while now and I can't seem to figure out what is causing it, and I can't really afford to throw parts at it since I'm going to school at the moment. Is there some way to diagnose what is causing this? Or has anyone else had a similar problem? I've hit a bit of a brick wall here, as I do not know how to check what could be causing this.