Repair-It

Ordered the Continental belt kit plus 3 pulleys for $134 from Rockauto.

Just checked P/S pump reservoir and the level is perfect. Definitely hoping it's not the P/S pump or alternator. Rather than try to diagnose I just decided to do the kit. Hopefully the pullies aren't a huge pain to replace. Access isn't the greatest so we'll see.

I think it's the power steering pump. Using the screwdriver technique against the reservoir cap as well as using a tube to guide the localized sounds to my ear it does seem to be emanating from the P/S pump. I jacked the front end off the ground and tried some manual lock to lock to "bleed" it. No difference. I also tried lock to lock with engine running, on the jack. No difference. The whine doesn't seem to change at all with power steering input. Still seems like the pump though, even though nothing abnormal at all is felt in the steering wheel. Maybe that means it's a bearing...

I do have some good news.

The pulleys and tensioner look easy to replace (no special directions, other than presumably tight access). They want you to stake the tensioner before removal and stake it before installation. Other than that it looks super straight forward.

Other good news is that the P/S pump R&R looks.....dare I say, easy? Maybe access sucks but the ONLY extra thing they have you do is remove this upper coolant pipe thing. So that will add some mess to the job but I don't mind doing a poor man's coolant change with this job or maybe I'd even drain it from the bottom properly.

Even more surprising news, this car is configured with the simplest power steering situation of all of the W221s. Obviously the ABC cars have this fancy tandem pump that does both power steering and the ABC system and it's WAY more expensive. There was also some kind of electrohydraulic (semi-EPC?) system that may have come on the facelift 2010+ cars that I also don't have. So it's just a regular old P/S pump.

OEM part is $333 for a reman. https://www.mercedesbenzpartsshop.com/o ... dhcw%3D%3D

At least a 1 year warranty on that.

Options on Rockauto are even more reasonable.

Cheapest new is an Ultra-power for $125.79 which I probably wouldn't buy. 1 year warranty.

There are three AAE options that all seem slightly different? One includes reservoir. One includes the return pipe. Prices for those range from $174 to $193 and have a 2 year warranty. There is also a Cardone new pump for $280 that I can't see touching with a 100 foot pole. Lifetime warranty on that.

Then there is a Cardone reman for $184 with a $26 core. 3 year warranty.

Honestly I might spring for the OEM in this situation.

But right now I'm not going to do anything. I want to keep using the car and see if anything alarms me. It does seem a little ill advised to drive 2500 miles with what seems to be a whining P/S pump. I'm getting flashbacks to Jamie's SRX that shit a pump at around 93k on our NH vacation. That sucked. That pump also really sucked to do. Hopefully this one is way easier.

Did the two idler pulleys and tensioner, plus new belt. I'll cut to the chase: the whine is still present and I assume it's the P/S pump. I didn't start it with no belt but I assume there would be no noise.

The job wasn't too bad though access is a bit tight between the engine and fan. Not sure how they cram the V12 in here but that must be why they suck to work on...

Anyway, release the tensioner with a 17mm socket and stake the tensioner in the loose position with a 3/16" drill bit. Apparently it blocks one of the mounting bolts if you don't do this plus it just makes life easier with the belt. Remove belt but don't forget to study or snap a pic of the belt routing. This isn't all that complex (I find my E55 a bit difficult) but access is tight.

The two idlers just unscrew with a center bolt. Takes like 2 seconds. I think one was a T-50 and the other an E10. Perfectly normal head types, move along.

The tensioner has 2 mounting bolts. They were.....E12. Getting the ratchet on them required two different length extensions but I got it. So this part wasn't too hard.

Once everything was out I felt the two idlers. They actually felt pretty healthy. Drat. However, the tensioner did not feel as good. It actually made a little noise when spun and definitely had a little play. Yay? OEM appears to be Gates and the tensioner in the Continental kit was also a Gates. Interesting. The OEM belt was MB and made in Spain. This Continental kit was made in Germany.

The new tensioner actually shipped with a stake/pin in it so I didn't need to deal with that part. But I really needed two hands to install: one to hold the tensioner on the timing cover and the other to slide a bolt in. But two hands don't fit! So it was.....interesting. I won't laboriously explain how I managed but let's just say part of the plan was to tape the bolt into my E12 socket for the lower bolt hole (could barely reach with my hand).

WIS said 35Nm for new idler bolts and also all tensioner bolts. Then 25Nm for used idler bolts. So I did that. The kit came with one new bolt for one of the tensioners. It mounted to the timing cover a little differently than the OEM one and also the OEM cover did not snap back on the aftermarket idler. So I left it off.

The belt was also tricky. Took me a full 15 minutes to route it around all the things but the actual path wasn't tricky, just access. Clearance even between pulleys is tight.

Got that all on and yeah it still whines. I did check the water pump which felt very good. Frankly the P/S pump felt good, too. Not sure what to make of that. Alternator spun silently. A/C compressor clutch seemed a little loose but it's a clutch so it will rock a little.

I guess I need to consider doing the P/S pump, as I predicted. But at least this maintenance is done. 79k and change (it's in Fuelly).

Before just blindly throwing a pump at it I decided to check with the forum first. Glad I did.

https://mbworld.org/forums/s-class-w221 ... matic.html

Here are the bulletins that may apply.

I'll just repost my post from there.

Thanks!! Those are all good leads. I'll try to narrow it down. I hope it's not the A/C pulley. Unless that's easy to replace with the compressor in place....

The noise does not change by switching the A/C compressor on and off. Evacuating the refrigerant will not change the noise since the A/C compressor belt pulley runs continuously with the engine.

It certainly would suck to do the P/S pump and have it be something else. They want me to get a shorter belt and cut out the A/C. That's a bit of effort and cost but I guess worth it. And I can't really think of a good way to isolate any other way. I wish I spun the A/C though I thought I did. It was hard to reach from the top.

So the list of potential fixes is:
- A/C compressor pulley (holy crap I just noticed the embedded MP3s!! That does kind of sound like my issue......hmmmm)
- P/S reservoir/filter restriction. Replace reservoir/filter.
- Improperly bled system. This one is unlikely. The car sounded like this when I bought it and hasn't changed at all. I also tried manually bleeding with the steering wheel technique as listed. Zero change.
- Or if not any of this, maybe it does need a P/S pump

So I guess it's probably #1 or #2. Or....it does actually need a P/S pump. But I'm now thinking it's something else. This is great info, thanks again.

I am leaning toward the A/C compressor pulley bearing now.
https://mbworld.org/forums/s-class-w221 ... -cars.html

And here are a bunch of options to replace. I wonder if any of these aren't Chinese garbage though.
https://www.ebay.com/sch/i.html?_from=R ... =0&_sop=15

Bought this one for $36 shipped:
https://www.ebay.com/itm/124851672397

Holding tool but I may not need this if I loosen the front plate from the compressor shaft with the belt still installed.
https://www.ebay.com/itm/122793969883?h ... SwhqhZ~4E1

Last time I tried to do the clutch I ruined the compressor. So.....let's not do that this time.

More helpful bulletin.

This is what the parts system says is compatible. It's the 120mm one. The one I bought says "4.5 inch." Which translates to 114.3 mm.

https://www.mercedesbenzpartsshop.com/o ... 0002341612

Not sure about $200 for a pulley....might roll the dice with my eBay one assuming everything checks out and I feel like the size/fitment is acceptable. But I might need to get a tool....

Step 1: install the A/C bypass test belt and start engine.

Results: no whine. Well how about that. So it needs an A/C compressor pulley.

Fun fact: this compressor does not appear to be clutched. It may somehow turn off internally. Maybe it is variable displacement and that is how it turns off.

So I decided to just roll into the repair this afternoon. It wasn't too bad. Got to try the S550 on the Quickjacks. The hood ornament is contacting the ceiling.

It's a good thing I got the S-class rated Quickjacks. It's barely long enough for the jack points on the car but it IS long enough and that's the point. I used a tall block and a short block at all four locations. Worked great. To be clear, any other version of the Quickjack is shorter and would not have worked unless I picked different lift points.

The directions aren't that complicated. Although it may have been easier if I reinstalled the long belt to hold the pulley still.

- Remove circlip that holds hub from unthreading against the pulley. Just do some prying. It isn't that hard of a spring. The pulley is plastic for extra quality.

- Hold pulley from turning and turn the compressor shaft to the right (7mm socket). What is happening is the outer hub is being unthreaded from the compressor shaft. There is a 3 pin holding tool but I didn't buy that in advance so I tried various things. Ended up putting a belt on and used these Irwin clamps to hold the pulley while whacking the ratchet with a sledge. Eventually it just started loosening.
- Keep rotating bolt/compressor shaft and the hub will just walk off the pulley until it comes off completely.

- Remove snap ring. Had to grind down my snap ring pliers because they were too big for the ring holes. But eventually I got it removed. I probably spent a solid 20 minutes on this until I got it. Normally this takes 5 seconds but I had to modify my tools. I tried other things before that...

- With snap ring removed, just gently walk the pulley/bearing off the compressor snout. Comes right off with some rocking motions in different axes.

- New pulley is about 10mm larger. Well, hope that isn't an issue......
Here is the naked compressor with no pulley.
Fun fact: the hub transfers torque from the pulley with these rubber dog bone isolators for extra low NVH.

Installation is the reverse of removal. I ended up using my original snap ring because the eBay/China one seemed a touch thick for the snout groove.

The directions say to torque the hub to like 35 Nm. That seems crazy. It just needs to seat. Also, if the circlip fits, I figured it was on there enough. And the circlip fit so I didn't worry about the torque. It tightens while running anyway.

Anyway the noise is fixed. Very happy I tackled this and it went pretty smoothly. Another not-too-hard job on this car. Hope this bearing lasts a while.