TBRUENN

I just got a new 2012 CLS 550 when we start the car a loud metal noise comes from under the hood. It sound like a metal on metal sound. We brought the car to the dealer and they are saying that this is normal for the bluetech engines. Does anyone else have this experience or know whats causing this?

Thanks in advance.

TBRUENN

I forgot to mention that it goes away in a few seconds and is only there at start up

iMj

I do have the same sound with my cls63 12

Sathinas

It's called "cold engine start-up noises". When the engine is cold, engine oil is drained into the oil pan, you will have relatively unprotected metal parts grinding against other metal parts until the oil pump gets to circulating oil.

Unless it does it even with the engine at operating tempertature (aka, shut it down and then immediately restart it), you're fine.

TBRUENN

This is what the dealer wrote on my work order:
Owner states to hear a loud knoking sound from engine when first starting cold.. Vehicle was started cold...knocking sound is normal...this engine has a direct injection system and when vehicle is cold..thesystem is at a rich mixture...once engine warms up briefly.. noise will go away...engine is operating as designed.

It seems the dealer is blaming it on the direct injection not the oil? I am surprised that with over 150 views only 2 comments? No one else has or does not have this noise??
Thanks again.

BarrettF77

If it is a direct injection system, the block/oil/and other mechanicals are all starting cold with the old also being down in the pan. You might check the oil level to ensure that isn't the reason for the sound.

I assume if the car is turned on and ran for a minute and then turned off and back on it will not reproduce this sound. Also, how long does the car need to sit before the sound returns. Engines tend to run rougher when the first turn on. Now the question might then be, why don't other engines make this kind of sound when turned on. How many other cars have you bought that direct fuel injection as well as the boost of two turbos on a V8 engine with over 400 hp and 400 ft/lb of torque? Parts are beginning to move and much faster likely due to the compression and power that engine has. Something to think about.

2020

Actually never thought about it. Does the CLS have a dipstick to check the oil or is it electronic. Porsches no longer use dipsticks to check the oil level.

BarrettF77

Pretty sure it has a dipstick. But haven't looked TBH.

konigstiger

Checking oil level...

Vish87

I had the same question. I hear the sound on the start up too... dealer told me the same thing also. mine is a cls550' 12.

Its not the prettiest sounds

Tariq

Hi guys,

I notice the same on my CLS350 Bluetech, the sound like knocking when engin start , i check with the dealer , they said its normal with the new blutech engines.

CLS550$$

I also have a brand new 2012 CLS550 4Matic and also went to the MB dealer with this issue... The mechanic and or so called expert told me it was normal as well for this vehicle... Its kinda annoying that a car costing 85 grand makes a noise that remenecies that of a old mercedes diesel !! I was told it was due to the fact of the high compression rate the engine has...

CLS550$$

TTT

hellasmania219

took in 2013 CLS550 4matic for this issues. First time dealer said it is normal sound. Second time they claim there was a service bulletin for it and ordered parts (belts, tension something, i wasnt paying attention).

Now i have car back, still making the knocking noise and have coolant spraying everywhere and leaking. Dealer sent a flatbed to tow on a sunday night....we will see what happens tomorrow.

Also, my 2009 ML350 made the same noise. My 2012 C350 doesnt have the issue, even though the direct injection engine doesnt sound as smooth.

raspu

My 2009 c300 with 47000 had this. the mercedes dealer keep the car for 9 day pull the motor and replaced the bearings ,problem solved will try to get you the mb-bulleting number it seen mercedes is aware and the solution is oversize bearings. I did have a loaner car document complaint with dealer and it will get done. It sounded like a colapse lifter and lasted 3-5 seconds, while she was hot no sound, but you let it cool for 1 hours and the noise was there..

raspu

C300 2009 dealer corrected this after keeping car and service mng heard it !!
results pulling motor out and replacing engine bearings (all) with oversize..will try to locate work order w/Mercedes bulletin number addressing this problem

frogs9497

Just wondering if you were provided with a bulletin number for this issue?

Stavs

Hmmm - I have done 1700 miles but I haven't heard anything like this yet. Was this noise there since you bought the car or did it start later? I wonder if it is isolated to specific cars.

DCubed

Are you sure you are just not hearing the normal turbo spooling when you start the car for the 1st time of the day? With all the new things out there to try and reduce the carbon emissions out of our cars, they do spool up the turbos on the new TT V8s to get the emissions control equipment up to temp quickly.

Randhut

To the original post of this thread by tbruenn....
we have 2012 CLS 550 4matic with similar issue and several threads on this forum (C-class) describe similar metallic startup rattles for the new blue efficiency engines. We all definitely do not refer to the slight diesel like injector sounds that are audible with open windows at idle.....those are perfectly normal and expected...what we hear is a brief metallic grinding, rattle sound at startup lasting 2-3 seconds at most. In our case it is most pronounced when restarting 1/2 to 2 hours after parking the car after a prior longer drive. When restarting the car within minutes post prior shut off the noise is completely absent (supporting the theory of oil drainage and loss of prime). It also seems temperature dependent, in the summer heat this phenomenon was much more pronounced than during spring (the time we got the new CLS). People on the other threads claim it is oil circulation related with loss of prime of the valves and they even list an official MB statement. I find it hard to believe that a car that achieves such a technical perfection otherwise on so many levels, would be designed with such an annoying flaw of poor oil priming/circulation (if it is detrimental for the complicated variable valve timing mechanism over time I cannot judge).
I have a high school friend in a high position in the German automotive industry and I am considering asking him about the e-mail of the head of engine development at MB (hard to get otherwise) to inform about this brewing issue. So I would appreciate feedback from all those that observe the same issue (again it is NOT the idle clicking sound of the direct injectors). This is such a phantastic car and engine otherwise....I just want to get to the bottom of it!!!!
Thanks, RH

PS: to TBruenn...did you get your CLS also from MB of White Plains in Westchester...we seem to be kind of neighbors ??

TBRUENN

PS: to TBruenn...did you get your CLS also from MB of White Plains in Westchester...we seem to be kind of neighbors ??[/QUOTE]

Yes we did. Hi Neighbor!

raspu

Here it goes..W/8429 TOLERANCE INADEQUATE PERFORMED NOISE LOCATION TEST IN ORDER TO DETERMINE LOCATION,FOUND COMING FROM LOWER END
FOUND NEEDING CRANK BEARING REPLACEMENT,DISCONNECTED GROUND LINE
DRAINED ALL FLUIDS, R AND R ENGINE,R AND R TRANSMISSION, PLACED ENGINE ON ENGINE STAND AND R AND R UPPER AND LOWER OIL PAN R AND R ALTERNATOR, R AND R STARTER R AND R REPLACED ENGINE CRANK BEARINGS AND INCREASED SIZE AS PER SHEET,CORRECTED FLUID LEVEL, ERASED FAULT CODES, TEST / DRIVE PERFORMED. CAUSE:941013 LOCATE W-8429
PARTS:
1. 272-033-39-02-56 MAIN ENGINE BEARING
2. '' '' '' '' '' '' ''
3. '' '' '' '' '' '' ''
1. '' '' '' '' '' '' ''
8. 000000-001811 screw
8. 000000-001810 screw
6. 910143-008018-64 screw
2. 910105-008037 screw
1. 272-033-42-02-56 main bearing
1. 010-989-90-71 cleaning age
1. 001-986-71-71-00 cleaning com
1. 003-989-98-20-10 sealant MB
1. q-1-03-0004 anti corrosion
1. q-1-32-0001 hydraulic oil
1. 000-180-26-09 TS filter in
1. 007603-014106 seal ring, VL
9. q-1-09-0144 MOBIL 1 form
012800 engine with AUTOM. trams r and r 8429 W
272110 AUTOM transmission r and r (engine w transmission removed)
014270 engine in assembly stand tighten (engine removed.output side exposed for access) 8429 W
034291 crankshaft (engine removed, output exposed and replace)
**plus loaner for 9 days and courtesy wash on clients vehicle.

Hope info help's (3-5 sec cold crank start) NORMAL ?? Raspu

raspu

W-8429 IS THE KEY............AND OF COURSE A GOOD DEALER WITH A GREAT SERVICE DEPT.

Randhut

Yes we did. Hi Neighbor![/QUOTE]

Looks like nice Oktoberfest-beer....Cheers and Prost !

world is a small place and sometimes vast internet is very local....

we got ours from Peter Makay....did you bring the famous noise to their attention yet ?

Perhaps we should drive there and present them the noises in two car stereo quality....can also always be reached at rand.hutter@gmx.de;

frogs9497

Many thanks!