On my 1991 W124 300D w/ om603, it sounds like the pulley bearing on my AC compressor is going out. After starting it at the store tonight, with the AC off, I heard this low-level grinding noise from somewhere. I shut the car off, started again and the noise sort of subsided.

I took off the belt at home and spun the pulleys by hand. The AC pulley gave a slight squeaking noise when rotating, and the others spun normally.

My first question is, can I keep driving like this for the next few days, or will it seize up suddenly?

I believe the compressor itself is probably good. I've seen several other youtube
videos of people replacing the pulley bearings when they started making noise - they just press them out, put some red loctite on and press new ones on.

From searching around, it's unclear if there's a standard pulley bearing in these compressors which I could press out to replace, or if it is completely molded together and not servicable. It would save a load of money and time to just swap in new bearings...

Anyone have an idea if the AC pulley bearings can be serviced ?

If I'm in luck, it might be replaceable:
006 981 36 01 CYLINDR. ROLLER BEARING

https://mercedes.7zap.com/en/jp/fg/car/300/300+d+turbodiesel+japan/15y/124133/m/603960/588/13/0/060/0/0/#245

https://www.drive2.ru/l/2389783/

If the compressor is the same one as on a 91 M103, yes the clutch bearing is replaceable. Did it about 15 years ago with the compressor in place, wasn't overly difficult. I don't know about the location/accessibility with your motor.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

They are replaceable quite easily, its a denso compressor, the bearings are sold at parts shops too. You will need a small press to remove them. Or you can take the pulley and bearing to a shop with a press or an AC repair shop.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

can you fill us in on the dimensions of your new bearing please? or part number and source for the bearing? i am having this exact same issue right now. thanks

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

I purchased an NSK pulley bearing with these dimensions: 30*52*22mm .
The part number is 30BD5222 , or 30BD5222AT1XDDUM1 .

I got it from ebay: https://www.ebay.com/itm/163600090420 . Shipped pretty quickly. It's also on amazon.

It fit perfectly on my engine (om603). I imagine the same pulley works on other W124 or similar vintage Mercedes models.

I removed the pulley and pressed the old bearing out using PB Blaster, sockets, bearing drivers and a vice. I then cleaned up the pulley, applied some thread locker to the outer surface of the new bearing and pressed it in using the outer race from the old bearing in a large vice. The video I in the link shows some of how to do this I think.

This repair would have done the trick, except that when I was removing the pulley, after taking off the c-clip holding it to the housing, I used a wooden dowel and 4-lb hammer on the back out edge of the the pulley to free it from the compressor. It eventually came off just by mildly tapping, pulling by hand and rotating. However, in my hammering, I inadvertently snapped off half of the cast aluminum flange of the compressor which the c-clip rests against. So I couldn't install the fixed pulley with new bearing at all because there wasn't enough material to support the c-clip. I had to scrap the whole thing and I'm putting in a brand new DENSO compressor instead, and will have to evac and recharge the whole system.
So, anyone doing this, be careful of that fragile inner c-clip flange when removing the pulley, it should come out by hand force, or light tapping alone once you've removed the c-clip.

Nothing hurts as bad as a self inflicted wound.

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