Hi all,

I've been reading MBworld since about a year, with great interest.
Unfortunately my first post is to request for your assistance in diagnosing (sort of) a weird sound that popped up a few weeks ago on my 2012 C63 Performance Pack (or P31 in the US)

I am planning to have it diagnosed at the dealership in the coming weeks (I do not drive it much these days - too much work right now), but in the meantime has any one of you encountered that kind of noise on an M156 engine ?

Part 1 : Just after startup, Oil temp around 20°C (~70°f), standard idle engine sound, no strange noise

Part 2 : at about 50°C (~120°f), the noise starts to be heard gradually, at first irregular then more constant

Part 3 : from about 50°C/120°f to 100°C/210°f the sound is constant, and changes pitch as I depress the accelerator. It can only be heard between idle and ~1500rpm, above which it dissapears only to come back below 1500rpm (can be heard in the video)

Note that after a fast run with the car, oil temp rises between 110 and 117°C (230°f to 242°f). When the car is at that temperature, and idles, the sound is no longer there.
If I kill the engine, let it cool for a while, and start it again when oil temp is back between 50°C/120°f to 100°C/210°f, the sound is back again immediately.

Car currently has 22k miles on it, and no longer under warranty (i'm in Europe, only two years here).

My opinion is that this could be linked to a problem with the chain tensioner on one of the two chains at the front of the engine : timing chain or oil pump chain, which leads to the chain rubbing against the casing at low rpm, but no longer rubs at higher rpm as the belts gets more tension under load.
Relationship with the oil temp may have something to do with oil viscosity that may prevent the rubbing sound to be heard.

Any idea/advice ? Anyone had the same issue ?

thanks a lot for your help !

For those that want to hear the most significant clip, jump to 1:30 in the third video.

EDIT : sorry for the poor lighting and for the reversed view at the end of video 3
For clarification purposes, the noise I am not talking about is not the ticking, which is quite normal for the M156, but rather the whining noise that is present in videos 2 and 3

 

Sounds normal to me, my car sounds like that too at start up.

 

My car sounds exactly the same, even a bit more dramatic. It is totally normal.

 

Hello both,

thanks for your feedback.
Maybe the first video is a bit misleading : in the first video, the "unusual" noise is not present. I just put it there to show that the car runs normal at low oil temps.

You can only hear it in the second and third videos. I suggest you jump to 1:30 in the third video to hear it more clearly, that's when I start to change the revs.

I can tell you it is not normal for two reasons : (1) I did not have this sound for the past year since I got the car, and (2) I am part of a group of C63 owners around here where we have around 6 regular C63s and 2 C63 BS, and none of them exhibits that sound...

Let me know what you think

 

Bump for help on that noise (see above, not the ticking noise, but the humming that changes pitch with revs...)

 

Do you mean the whining sound?
I believe all/most AMGs have this whining. My E55 has it when you rev


Good luck


Faiz

 

I think I need to find a better way to capture the sound . Unfortunately I do not have an external / directional mic, which would help single it out.

The noise I'm talking about was not there for the better part of the last 18 months on my car, nor is it on 6 or 7 other C63s I know. So it's definitely not a "normal" M156 noise. I'm not saying this requires immediate attention, but I'm definitely curious to see if anyone ever heard it on his car (if I manage to properly record it)

The best I can tell you is to look at video #3 starting 1:30, where you can both hear the noise at idle, hear it rise in pitch between idle and 1500rpm, and dissapear above 1500rpm

Thanks anyway

 

If its the whining noise, it sounds pretty normal to me.
Have you checked oil level?

 

Yes, oil level is perfect, the car runs absolutely fine otherwise.
Oil was changed recently with the new AMG oil (which I believe is now 5W40). Noise was there before the oil change, and still there after.

This is really nerve racking and much louder in reality than how it appears in the video (in the video it seems to be in the background for some reason).

 

Slip the serpentine belt off, start the engine and see if the noise goes away, sounds like a bad idler pulley bearing, which will change pitch with rpm. Only run for no more than a minute, water pump will not be turning during the belt off test
Spin all idler pulleys by hand and check for wobbly or ones that spin for a long time, trouble a brewing.
Worth a shot, EH!

 

I really don't think trying to self-diagnose a car by running the engine with the water pulley disengaged is a good idea at all.

 

Not by myself, but good advice to give to the dealer before they pull out the engine completely to replace the timing chain tensioner or oil pump chain tensioner...

By the way, my indy tells me that the only way to perform the chain / chain tensioner replacements safely is to pull the engine out entirely. As this costs an arm and a leg, does any one of you know if this is really necessary or if there is a way to do it with engine in place ?

thanks guys!

 

This fellow came on board and asked for help, warranty aside, which in hindsight is probably the way to go. But he took the time to post numerous videos of his issue, so in effect he was asking for assistance.
Also running a car for a minute without the water pump turning will do absolutely nothing to the engine, unless you have a better diagnosis, or would you wait until a faulty idler pulley melted and ripped a few hoses off. I like to be proactive not reactive.
Had the idiot tech at MB tell me the noise I heard was normal, Yah it was normal for a bad idler bearing which failed 2 days later, I trust myself, telling him failure was evident. By the way the tech is now deaf in one ear from the dress down I gave him, endangering my family when the serpentine belt was destroyed leaving me to handle a 2 ton rock, no power steering ( try it).

 

@realjones88, just how much coolant is circulated when the thermostat is closed?

 

Did you ever figure out what the noise was? I am also out of warranty and freaking out...

 

I think I have the same issue. When the car runs cold I have the noise and when I go to 1500-2000 rpm it disappears. My noise comes mainly from the bottom of the back left seat and it is like something turning or a cyclic sound.

Any feedback if you found the issue? Thank you.

 

I have a feeling it is the oil pump or a bearing going out in the block.

 

Very much doubt that I have the same noise im not concerned been like that for a year since I bought it. Sounds more like a power steering pump or potential pulley to me but I see no obvious issues there

 

Sounds like a pulley issue.
Did you have it checked by the dealership?
What part of Paris are you?

 

Here is a video once the car is turned off and the rattling still continues for some minutes... is this normal? The sound as mentioned, comes from behind the bottom of the left back seat. Thank you for the inputs

Note: If you don't hear it, turn the volume and sorry there is no image

 

Run the car without the belt on it. Obviously don't let it run until the point it over heats, but this will rule out the pulleys and accessories.

 

To me that noise is normal as any engine will do when you shut them off.
It is a thermal effect indicating your engine is cooling off (like cats or else)
Does it stop after some time?

 

Yes, it stops after some time, but it makes that similar noise when the car is on. I will try to get the sound when the car is one.

When it is idling it sounds similar but inside the cabin and when accelerating the sound gets faster everytime until the 1500/2000 rmp. Over these rpm it stops or I can't hear it because of the engine.

 

Did you ever figure out what it was making that noise?

 

Here are the new videos. You can hear as accelerating the noise gets faster, until going over 1500/2000rpm that is disappears.

Thanks for the feedback.