Like the title states, what do you all think? I will be getting a shorter belt in the meantime to eliminate the compressor. Couple things worth mentioning:
1. Whine increases with RPM.
2. Turning the wheel left/right does not affect the noise it seems.

Link to short YouTube clip:

Thanks

 

My ac compressor recently went bad and I had it changed for around 1000$, but I don't recall it sounding like that at all. I'm not a pro but just thought id give my input, I'm guessing power steering pump since when my ac compressor was fried, due to flooring it and redlining it with ac on max cool ( I know, you live and you learn ) it didn't make any sound near that. Good luck, let me know what conclusion you come to.

 

Also the area where you point the camera and it gets louder, that's where the power steering pump is so I'm really going to assume it is that. How many miles on your w211?

 

I will have more info once I get the shorter serpentine belt in order to bypass the AC compressor. It really is hard to tell as the PS pump is right on top of the compressor. Thanks for the input.

 

I am 200 miles shy of hitting 150k. I've had this sound ever since I bought the car with 132k, but recently it's been getting louder and I wanted to address this issue as I am thinking of selling the car.

 

Purchase a mechanic's stethoscope so you can pinpoint the item making the sound.

 

I've used that but I can hear the resonating sounds all over the engine block. I could hear the same type of sound for the both of the parts. Thanks though.

 

Update. With a lot of effort, I found the shorter belt to bypass the compressor. For anyone who is interested, go to Autozone and ask for a 91.5in Duralast 6 ribbed belt (~$35). Once I bypassed the compressor, I had my fingers crossed that it would be the PS pump. Unfortunately, it wasn't. In fact, my compressor produces a TON of whine. I was amazed as to how quite the engine was w/o the compressor hooked up. So changing the AC compressor is going to be my weekend project. I will post a new video of "after". Thanks for the input.

 

Change the power steering fluid. Use a suction gun empty the pump, refill with the CORRECT fluid that can be bought at NAPA for about $30/can.

Fill with correct fluid, drive about 100 miles change again. Do this total of 3 times and see if noise goes away.

It could also be the belt idle pulley. I use a 1" pvc pipe to act as a stethascope to hear sounds. Point it at the idle pulley

about 1" away free of biting whirley thingies and listen to the other end of the pipe. See if you can hear the sound.


90% sure it ISN"T a/c.

 

I recently experience this condition in July of last year. I was under the impression too that it was the power steering pump, until I was able to isolate the ac compressor belt and sure enough it was the compressor.

I believe you are on the right path.

 

Vettdvr, I actually did do a flush of PS fluid (CHF11S), but the whine was still there. I did not bother with it until now because I started showing the car to potential buyers and the sound scared most of them away. I know that it is the compressor making the whine because the short belt I bought simply bypassed it. Short belt connected idler roller, water pump, generator, crankshaft, and PS pump, leaving out the AC compressor. Like I said before everything was quite when I started her up.

The procedures you provided can help people with PS pump issues for sure. Thanks

 

You're most welcome. I try to be helpful. Probabilities were pump or idler vs compressor. But if the compressor is making noise change it before it throws metal through the system. IF it is cooling now and working your system is probably still free of metal and the filters will catch what has already passed. Just change it soon while it is still cooling.

 

I had an grinding/moaning noise in my '07 E320 Bluetec that the dealer traced to a bad pulley on the A/C compressor. Replaced under warranty - based on the parts list - they performed this procedure:

Here is the English translation:
0,8,Noises at the refrigerant compressor |may be caused by a defective belt pulley.||
8,12,This belt pulley can be easily replaced. |||
12,16,Important: |Only remove it when the engine is cold!||
16,19,If the engine is hot, |replacement of the belt pulley ...||
19,22,... is not possible due to material expansion.|||
22,26,Slacken and remove the poly-V belt.|||
26,30,Now remove the large circlip.|||
30,33,Detach the drive plate:|||
33,37,To do this, turn the socket on the compressor |shaft clockwise and ...||
37,42,... the counterholder on the drive plate |counterclockwise.||
42,47,Important: |To prevent damage, the belt pulley |must be unscrewed by hand ...|
47,50,... in the counterclockwise direction.|||
50,53,Remove the smaller circlip.|||
53,58,Pull the belt pulley off the shaft |without exerting excessive force.||
58,61,If the spacer ring on the |compressor shaft gets lost,||
61,64,there is a new one in the |replacement parts kit. ||
64,72,Installation: |First the spacer ring is fitted.||
72,77,Important: |The rubber dampers of the new belt pulley |must be positioned on the flat part.|
77,82,If they are installed incorrectly,|consequential damage cannot be ruled out.||
82,86,Install the new belt pulley |with the rubber dampers.||
86,90,When fitting the small circlip,|make sure that it is installed ...||
90,93,... with the flat side facing the compressor. |||
93,98,The side that is chamfered on the inside |diameter must face the front of the vehicle.||
98,102,Important! |If the circlip is incorrectly installed, |consequential damage will definitely occur.|
102,108,Screw the drive plate |onto the compressor shaft.||
108,113,The gearing on the drive plate meshes |in the gaps in the rubber dampers.||
113,117,Spinning the belt pulley clockwise ...|||
117,121,... screws the drive plate |onto the compressor shaft.||
121,124,The drive plate has reached |the end stop when ...||
124,127,... the compressor shaft starts |to rotate and the large ...||
127,130,... circlip can be installed in the belt pulley.|||
130,134,Important! |When installing the large circlip, |make sure that it is properly seated.|
134,136,Finally, fit the new poly-V belt. |||
136,138,This concludes the procedure |for replacing the belt pulley.||

 

@apl175, Thank you so much! That is extremely helpful. I went with simply replacing the compressor as the pulley by itself was $200 plus shipping. I managed to score a brand new Denso compressor for ~$300 shipped. I figured that the compressor ran for 150k miles and it was time for a replacement anyways. However, again, thank you for that video as I was actually contemplating replacing the pulley but could not find out how to take the damn thing off.

Here is a pic I snapped of the old and new parts side by side:



Exactly the same. I was actually surprised that the original was Denso as well just with a MB part number (with a C on the end). Made in Japan and will most likely last another 150k miles. I will post an "after" video of the running engine tomorrow.

Although I must say that changing the pulley seems much less invasive. To replace the compressor I had to:

1) Remove the tensioner
2) Remove the power steering reservoir and after that remove the pump (Drain the fluid before this).
3) Remove the compressor
4) Replace the dryer (silver cylinder in front of the radiator)
5) Replace the release valve
6) Put the new compressor in
7) Add oil to the compressor
8) Fit all the hoses back
9) After this, you need to vacuum the system (took about 1hr)
10) While you are vacuuming the system, put the PS pump and reservoir back
11) Top off the PS reservoir with CHF11S
12) Add one can of the refrigerant and crank the car for 1 second (this will pump the oil throughout the system)
13) Repeat step 12 couple more times
14) Start the car and turn the AC to the lowest temp and highest fan settings
15) You should have some pressure in the AC system now
16) Keep adding the refrigerant until you reach the specified level (2.10 pounds for me)
17) Bleed (turn the wheel all the way left/right) the power steering system and keep adding CHF11S as the level drops in the reservoir.
18) Repeat step 17 until the pump is not making any noise
19) Enjoy ice cold AC without any horrid whining noises.

 

Would've done the same in your situation - given the price difference. I hope this means you've decided to keep your car!

 

Will definitely drive it at least until next spring. Fell in love with it all over again.

Before:

After:

 

wow sounds so quiet now, unbelievable. I give you a lot of credit for doing that on your own, cheers

 

I'm going to be doing this to my w209 (2005), how did you get to the rear bolts on the ac compressor?! It's such a tight fit I can't seem to get anything in there to remove the bolt to remove the ac compressor.... arg!

I have a lift in my garage and all the tools but damn some of this stuff is super tight, on mine the ac compressor is on the bottom right of the engine (driver side looking straight on the car from the hood)

thanks,
-Nigel

 

Let me chime in with a comment on this issue...I had the same noise in my A/C compressor that is described here, though probably not so loud and only when the weather was moderate, i.e., not very cold or not very hot.


I solved it with a pump-down, recharge and the addition of 2 oz of Denso A/C oil. My car is 10 years old and the A/C was apparently working fine but it had never been recharged. Now all is quiet again! My (unproven) theory is that when the Freon level is down a bit, there are gas bubbles in the line going to the expansion valve and these make a racket when the valve is running partially open. The noise is then transmitted back through the lines to the compressor and through the car body.


Thanks to everyone in the thread who helped me figure this out!

 

Does this work for 2005 s430, I have the same exact problem

 

I have a 2007 E350 and it has been making a winning noise for a few weeks. First thought PS pump, but noise does not change when turning wheel left to right, instead replaced guide pulley because of bad bearing, but still have some wine, but not as loud. Now thinking it's the A/C compressor. I have 110k miles, wondering if just replacing the pulley would do the trick or even doing the pump down and recharge before tackling the complete compressor replacement? I've already replaced the drier and evaporator 2 years ago. I hate to keep throwing money into this car, even though it's a great car. There seems to be so many issues with it. Just when it's running good, something else expensive fails. Suggestions?