Idler pulley




The pulley that was installed was 2722021019.
Turns out thats the wrong one, if it's before 7/2007.
It's supposed to be,
ML 350 Idler Pulley- 0002020919
Bolt for above- 1129900012
Cover- 00019885735
the inside diameter is different, the bolt has a lip that supports the bearing, and the bearing also fits over a protrusion one the water pump, thats not there on later models.
The 2722021019 has a plastic piece that supports the pulley (lame!)
but when you bolt it in to an early ML it pushes the plastic piece to the center of the bearing and nothing supports the bearing.
Looks like this.
when it gets bolted onto the older version water pump, it pushes the back plastic sleeve the the center, and eventually locks it.
So, just an FYI. The shop says they see a lot like that.
They can't figure out why that is.
Last edited by C230 Sport Coup; Oct 27, 2014 at 04:38 PM.


