My 2001 Excursion is making a strange noise. At idle I get an intermittent squeak/chirp. While driving it makes a sound more like a card in bicycle spokes. Also sometimes makes a droning sound. At times I can even feel a high freqency vibration thru the floorboard. It is load related - as soon as I lift off of the throttle, the noise/vibration goes away.

I just replaced the idler, tensioner & water pump, so those bearings are OK.

I did pull the intake tube off of the turbo & checked the bearings for play/roughness. Everything there is smooth as silk, so I think that the turbo is OK.

Could I have an exhaust leak that is making this sound?