Ok guys, I looked and can't find any earlier posts on this.

1996 Explorer Sport 4WD 4.0 107,000 miles. The other day I start getting this noise at idle that is like a grumle. I first thought tensioner pulley or idler pulley. Replaced tensioner and checked over the others and did not find anything to seem wrong there. Started it back up and the noise is still there.

Got to checking around and trying to find the noise and can't seem to pinpoint it at all. Here's what I've noted with it so far. Does this only at idle, Put in gear and hold brake and it gets louder, turn on AC and it gets louder yet. Increase in RPMS and it goes away. It is not running rough at all and no noted loss of power whatsoever. It sounds like the motor is coming apart sitting at a stoplight and the noise is similar to that of a knocking/rattling. No check engine lights or fluctuations in RPMS and like I said, as soon as you increase the RPMS by as little as a couple hundred it is gone. I don't know what to make of it at all, there isn't even a vibration through the steering when it does this. Any clues???

Thanks From Missouri! (The new desert)

 

suggestions? anyone??

 

The symptoms sound like it could be the IAC valve, although that sound is usually described as a 'howl'. Have you checked the exhaust heat shield or any other brackets on the engine that might be loose?

 

Does it it quiet down when the ac compresser stops it's cycle? You might want to take the belt off and check the pullies on the alt,water pump ect. You might have a bearing going bad in one of those. Let us know what you find.

Fitter

 

With the car shut off ! grab the plastic fan and try to turn it! if it moves with little resistance your clutch fan is not the problem.
But if you can hardly move it,your clutch fan hub has failed an you need a new one.
Rich