UPDATE: Issues resolved at the Main dealer. Issue 1 was pulley, issue 2 was water pump/thermostat

Hi Guys,
I haven't had any luck on the W222 forum so I am trying my luck here. I have a Mercedes S63L W222 with the M157 engine. (2016 model year.)
As most M157 engines are the similar/same I would like to get your opinion on this noise in case anyone here has had that on their E63 with the M157 engine.

Took it to Mercedes dealer and they couldn't hear the noise or source the problem. Sadly not many experts on the M157 here in the UK at main dealers. Technician says rarely get M157 engines here. Things I have done so far:

• Noise seems apparent around the Water pump were the pulleys are.
• I did 3 Compression tests using Xentry with 12 rpm difference (1 test had 25rpm difference). No issues here
• Starts first time, no rough idling or misfires.
• Power is there and quick.

I would be grateful if someone could shed some light

 

It is rather hard to diagnose remotely. You probably looked into some of the same places I suggest. Rattling and whistling likely relates to something spinning. See if the noise character changes with revvs. Take the serpentine belt off, examine wear, cracks, oil contamination. Inspect all pulleys for integrity, free rotation where possible. M157 belt drives 3 devices only: alternator, water pump, and A/C compressor. The other pulleys are idler. I replaced my OEM pulleys and belt at 58K miles, and bearings still had life in them for another 20-30K. Best of luck to you.

 

Thanks for this, I will take a further look later today

 

The digital electronic test is no longer used in later versions of xentry on the M157 any longer.

can you take a picture of your water pump pulley? I would like to see where your belt is on the pulley

 

How many miles on the motor? Have you checked the pulleys when engine off? Any play when you try to wiggle them? I can totally hear what you're trying to describe but nothing else comes to mind.
Have you had an impact on the bottom panels up front? Fender liner loose?
Is the belt tensioner jumping around? Idle sounds solid.
Interesting to find out what it is.

 

Luckily I had a 2017 version of Xentry installed on an old laptop so I connected my Star C4 and it let me do the Compression test.
And yes you are correct new version of Xentry doesn't allow you to do Compression Test electronically anymore.

Yeah no worries I will take a video and a picture shortly today :-)
Thank you

 

It's only just turned 30k, all main dealer services too.
And not tuned either :-(

I wasn't confident loosening the belt so didn't check them for play.
I did visually check when car was running to investigate the noise, may be I think i will do a video for this too later today.
I checked pulleys when engine turned off, they seem solid but then I'm guessing the belt will keep them quite tight so movement will be limited.

I will take a close look if I can today for anything that stands out of the ordinary.

The belt tensioner seemed fine but I may be wrong, think it's time I make a video of the engine bay area today lol

 

Top View of Engine Bay (M157):
https://www.youtube.com/

Engine Bay - Different Angles (Cold Start) - M157
https://www.youtube.com/

 

It's hard to tell from the videos but for sure, it's one of those pulleys. Best of luck. Let us know what you find.

 

I found the rattle noise coming from this unit/pulley using a stethoscope

Does anyone know what this is below? (It's not my engine by the way lol)

 

Are you talking about the diesel like sound or is there another rattling noise that I'm missing? I've always heard that the M157 is a noisy engine when warmed up, some of the noise you're hearing comes from the injectors.

 

That is the belt tensioner mechanism that loads the pulley directly above

 

Accessory Drive Belt Tensioner Assembly
p/n A2782000570
$161.46

 

Release the tension on the belt and check all pulleys. You might need a second person to hold the tensioner. Don't drop the belt though. Not fun to get it all back together.

 

Tensioner mechanism can be locked with a drift or just allowed to go to it's full movement.
Thinks it's 14mm of the nut on the pulley, breaker bar gives nice control over it.

Well found !

 

check oil level, drive get the car to temp, then let it sit for 30 minutes should be between low or half. If it is cold full it is wrong in my experience, cold full should be about half an inch above max. If you check right after running it will be low. For my car at least. borescope cylinders.

 

Hello, I am having the same issue with my engine, unfortunately it seems it's the engine internals.

Be careful as you can easily cause catastrophic damage.

Happy to share more details, let me know.

 

Update:
Okay so finally got my car back after waiting over a month for just the part.

1. Rattle problem has been fixed (Belt Tensioner) BUT...

2. Whistling/whining issue: still exists, I can see very small puddle of oil under intake manifold and experience slight high/low idle when I start car from cold.

Any ideas where to look so I can pin point and get he car in at Mercedes again.

I have the M157 engine, will attach pictures later

 

What did you end up figuring out for this?