At 160K miles today I hear what I thought was a dragging brake pad noise but as I parked and reved up the engine to 1500-2000 RPM
I can hear what can only be described as a dragging brake shoe noise but obviously I was parked so its not that. The sound is coming from the front of engine
and I am afraid to keep driving it till I can ascertain what it might be. Any insights would be greatly appreciated on the best way to diagnose this.Thanks in advance for your input.

 

It is probably one of the Idler Pulleys or both (#5 in PDF) or any other pulley or the belt itself.

 

Thank you so much for your input. I was thinking of removing the poly belt per your pdf that you sent and starting the engine to see if the noise goes away?
Will I harm the engine in any way by doing this for a brief time to make sure that the noise is not an internal engine problem? Would love to get forum input.
Again, many thanks for all suggestions.

 

Is your ML350 Gas?

Yes you can remove the belt and run the eng. for a min. or so, the turn off the eng.

After you do that, check the belt for cracks or wear.

If the noise disappeared, spin the idler pulleys with your thumb as fast as you can. If any of them free-wheel, they must be replaced.

 

I removed the belt and the noise went away. The upper idler pully was bad and the A/C pully had a slight bit of sound compared to all the other pulleys.
I checked the belt and it was in good condition. I put the belt back on and a week later went to buy parts driving the car. When I started to replace the upper idler pully I noticed
that the belt was frayed on the inside edge closest to engine so I went and bought a new belt and checked it for size against the old one and they matched up.
Installed the new upper Idler pully and new belt and test drove the car. I noticed that there was still a little noise so I assume that the A/C pully will need to be replaced as well.
The big problem is that the new belt is starting to fray on the inside edge after only driving about 10 miles. Both the old and new belts frayed after I installed them. I wonder what I am doing wrong?

 

Do you still have the original belt? If so, what is the part #?

Post your vin#.

 

My Vin # is:4JGBB86E36A089582
The original belt that was not damaged at all till I took it off and reinstalled it has a part number of:
Mercedes-Benz A001 993 18 96 6K 2398 EM 7122 also has this number too 11W32 BE 145

This is the old belt that is frayed on one side The new one is starting to do the same thig.

This is the new belt i bought and installed.

The new belt is a Gates K060947

 

The Gates belt you ordered & installed has been superseded with 003 993 72 96. This was not Gates' fault.

Order a new Gates belt with the new number.