My buddy's '04 3500 broke the serpentine belt. He put a new one on, and right away discovered sort of an intermittent vibration. He listened around on the engine and thought it was the idler pulley. (#3) Bought a new one for $85, put it on, and still has a vibration that comes and goes.
Anyone had this & found the culprit? He's stuck at home without his truck & doesn't want to have it break on the highway.

 

Does it vibrate at idle where he can watch the belt? Just wondering if maybe when the belt broke, the tensioner might have been damaged and is catching right where it tries to keep the belt tight and not keeping an even tension on the belt. Might try taking the belt off the tensioner and check the travel of the arm and spring. Good time to check the tensioner pulley bearing too.

 

I had a belt let go about a month ago and took out the fan clutch also (belt wrapped around it). Since winter was already here I didn't think that the fan clutch was a priority. After replacing the idler pulley and belt I noticed that I also had a slight vibration. Replaced the fan clutch and all was good..

 

I had much the same problem and it was the bracket that holds the ps pump to the block. It was cracked in the lower part and caused much the same problem. new bracket at dodge is 10 dollars.

 

It could be a bracket that is bent or broken, a bent pulley, or a bent pulley shaft.

 

take the belt off and check all the pullys for play (AC, alt, water pump, PS pump, etc...) everything that will move freely.

 

Also check to see if there is something (pebble, piece of old belt) lodged in a pulley drive groove or if one of the pulleys has a flat spot.

 

Being it is intermittent, I would check the radiator fan/clutch and the ac condenser. Both these items only engage when needed (intermittent)and they could cause the vibration when operating if damaged. Take a good look at the fan blades for cracks or pieces that may have broke off when the original belt let go, it may have damaged something and threw it out of balance.

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