When I changed my serpentine belt, I went ahead and tested, spun them by hand, all the accessory pulleys to determine the condition of the bearings.

Vehicle is a 99 ML 320 with 117K miles.

I found all were ok except the idler pulley which felt and sounded like it had no grease in it at all and the bearing in the A/C pulley for the clutch, which made a rumbling sound.

I put in a new idler pulley, they are cheap and very simple to change.

As far as the A/C clutch goes. I removed the spring plate, snap ring that retains pulley and pulley. I then removed bearing from pulley. The coil is not removed. My bearing is a Koyo part# DAC355222RR9D, it measured 35mm x 52mm x 22mm. That size is commercially available.

Below is a picture of what I removed. This is done with compressor mounted in vehicle.

I’m thinking that by changing the bearing before it fails will help extend the life of the compressor. The MSRP on the clutch from dealer is $730. with the MSRP for the compressor being $945.

Attached Thumbnails

 

Yeah, The Stealer quoted me $750 just for the clutch. Got one from Phil at Fastlane for $148.

The bearing on my old and new pulleys was staked. Did you restake it or was the interference fit to your satisfaction?

__________________
2005 Pathfinder LE
2001 E55
1998 M3
1982 320i

If by staked you mean the little indentations on the old pulley by the edge of the bearing, no. I've not got my new bearing yet but I'm thinking I'll be fine just pressing it in. When I removed the old bearing those indenations did not seem to do anything, the bearing I removed was not even score on the edge when I removed it.

I've posted a photo below of the pulley and I've circled in yellow where those little indentation were located. Are those what you are talking about when you say staked?

Yep. Thanks for the info.

__________________
2005 Pathfinder LE
2001 E55
1998 M3
1982 320i

The new bearing came in today, fit perfectly, so I installed it in pulley. The clutch feels like new. I'm hoping to extend the life of the compressor and clutch for a good while.

Ron
I like your approach towards preventive maintenance.
I believe you also own a 300TE, don't you?
Would the same operation make sense in that vehicle as well?
Thank you, Bruno

__________________
_
1992 300TE 160 kmiles

Bruno,

I have two 1992 300s, one an E and the other a TE. I replaced compressor on the E two years ago so I confident that pulley on it's ok. Photo below of TE pulley, you can see the carbon part in the middle is cracking quite a bit. Suprisingly, the bearing is very quite. I could probably use a new pulley but I think I'll wait awhile since bearing is in pretty good shape.

I personally think it's a good idea to periodically take the belt off and spin all the accessory pulleys by hand and listen to bearings. On the M103 engine any of the bearing on the accessories can go bad. I've found bad idler pulley bearings, bad fan clutch bracket bearings, bad tensioner bearings, bad a/c pulley bearings.

When I say bad I mean they make a rumbling sound or you can tell they have no grease in them or are otherwise noisy and do not feel like they should when you spin them.




Edited:
I was at my friends shop this afternoon and he gave me a Mercedes clutch kit for my car which had come in without a coil. I did not want a coil anyway. The special tool also pictured is what he uses to change these out. He said it's easier than a snap ring pliers.

To bad I already had reinstalled my old pulley, but it's pretty easy to remove and with a free new pulley with bearing and spring plate it will not be a problem.

Thank you for the reply, Ron
Next time I'll have a look at all the pulleys. So far I have had a bad tensioner, air and water pump pulley. Idler pulley is probably the next candidate. I've just done the evaporator (after being encouraged by your post) and would hate to experience a blocked compressor in the near future. Such a kit from the dealer are expensive though, I guess?
Bruno

__________________
_
1992 300TE 160 kmiles

The kit from the dealer is very, very, expensive. If you need a clutch kit I found http://www.ackits.com/ sells a kit made by Borg Warner that would work.