My Durango with a 4.7 has started making a noise while it's running. The best way to describe it is grinding. It sounds like when a water pump bearing goes out. The problem is that I can't narrow it down to be sure. Even used a stethoscope, but it didn't help. The truck has approx 141,000 miles on it.
Had a friend of mine look at it and he said it sounds like the A/C compressor.
I know it isn't alot to go on.
Is there anything else that it could possibly be? I've debated on taking it the dealer to diagnose, but $100 a pop just for them to look at it is kinda hard.
Any help is greatly appreciated.

 

well one way to eliminates the ac is to remove the belt and then crank it but dont let it run long as you will also have no water pump or fan.. if the noise stops then you know atleast it is something belt driven and you can go from there .. while the belt is off spin ur altenator and water pump by hand and see if u feel or hear anything .. i have had alts bearings go out on me before and the alt still worked. water pupms will usually leak water out of the lil pee hole in them when the bearing goes out as it disrupts the seal inside and causes them to leak. just a couple of ideas

 

i got a 2002 4.7 durango and mine kinda does the same thing. it sounds like metal grinding. i have absolutely no idea what it is on my truck and it only has 75,000 miles. but mine only happens occasionally. while in park or driving. It happens not very often.

 

one more thing it could "possibly" be is the clutch in the fan.. ive never had one go out but it is still a possibility.

 

I appreciate the suggestions.
Yesterday, I took off the belt and checked the pulleys. All of the them spun. The a/c spun the least of all of them. Maybe 1 inch of free spin, but turned okay by hand. The tensioner pulley had a very little play, but spun very easily. Alt and water pump spun freely with no noise. Started up and no grinding/rubbing noise.
Put it all back together and the noise is still there. But I swear the more I listen, it sounds like its coming from under the intake. It's really more of a rubbing sound than a grinding, if that makes any sense.
The search goes on.

 

well if the noise was gone without the belt on then it IS one of those pulleys, it has to be otherwise it would have made the noise when the belt was off, when you spun all the pulleys did they all spin smoothly? or did one wobble a little bit, or have any play?

 

That's what I figured too. All the pulleys spun freely with the exception of the a/c. It would free spin about an inch, but turned by hand with no problem. I was told that is normal. The tensioner had a very little play, barely noticable. But spun really easy.

 

This was where I was going to tell you to look, yet you did and you found a problem. Replace the bearing in the Tensioner Pulley or Tensioner Pulley altogether and also check the Idler pulley (if equipped) for movement like side to side for any movement. I also would replace your belt and a maintenance thing.

 

they should all spin freely but no tooo freely.. if it has any play in it at all replace it . they should al spin about like the ac

 

Mine makes the same noise, usually when I just start driving, between my house and the entrance to my subdivision, then kinda stops. Of course never when my mechanic is with me (-:
It does sound similar to the water pump glistening grind. But a little more high pitched and lighter. I have noticed it's worse on cooler days.