Front engine noise. Help please
 

Just started maybe two weeks ago. Thought I heard a weird resonance in exhaust at 1200 rpms. Only there. Exhaust looks fine.
Have always had the chirp at shut down but that suddenly stopped. Everything on front of engine is original at 108k miles including belt. Had a mechanic friend of mine listen to engine and he thinks its a pulley going bad. Couple of times last few days at shutdown it sounded slightly like a gear grinding sound.
Any help or tips would be appreciated. I have a new belt ready to install and ordered a belt tensioner, idler pulley, and water pump.

Possible fan hub bearing, this is the bearing that the fan clutch connect to, if you hear noise the loudest standing directly in front of truck. Check for any play in waterpump bearing, serp belt will need to be removed from water pump to check for play.
Fan bearing is located at location 5
water pump is #2
1 - GENERATOR
2 - WATER PUMP
3 - IDLER
4 - POWER STEERING PUMP
5 - RADIATOR FAN PULLEY
6 - CRANKSHAFT
7 - AUTOMATIC TENSIONER
8 - A/C COMPRESSOR

Here is the belt routing you may need this.


1 - GENERATOR PULLEY
2 - WATER PUMP PULLEY
3 - IDLER PULLEY
4 - POWER STEERING PUMP PULLEY
5 - RADIATOR FAN PULLEY
6 - CRANKSHAFT PULLEY
7 - AUTOMATIC TENSIONER
8 - A/C COMPRESSOR PUMP PULLEY

Idler pulley bearing went bad on my '05. Probably at about 100,00 miles. Sounded like a whistle at first. Two or three days and it deflected enough to cause the belt to split and fray.

Thanks guys. I have a copy of belt routing I've kept in my truck since new but appreciate the engine diagram.
Once I remove the belt and check all the pulleys, how do I check for clutch fan bearing? Would there be excessive play front to back or side to side?

Beleive it to be fan hub bearing, mine sis same thing. Very high price bearing like 220 bucks through dodge, went to local industrial bearing wharehouse and got the same bearing for 45.00 bucks. Its not hard to replace just tight working quarter's, would recommend chaing out the fan clutch since you have to remove it to replace bearing.