Steve Chandler

Hi all,

I know this has been an ongoing topic the past few years. My 2009 C300 makes the knocking sound after it's been sitting for a while. Should I make a trip to the dealer or just leave it alone? What is the experience others have had with just leaving it alone?

RuskiBenz

Personally i have read up alot on it and even though my car I just acquired doesnt seem to have this I would say leave it alone lots of threads I read had guys with 75k+ miles no issues its only first few seconds when u start up my dads both subaru did this inlcuding his new one and all were fine without hiccups. you dont want the dealer ripping your motor apart they dont have same expiernce factory does.

frogs9497

I know this has been discussed ad nauseum, but I have the same question. Here's what I don't understand: earlier models, such as my father-in-law's 1984 MB 380 SL, make the same noise. If this were an ongoing issue, wouldn't MB have addressed this in later models? My father-in-law hasn't had any issues and he's well over 100k miles.

I have no desire, as RuskiBenz said, to have the dealer remove the engine for this. And not that I necessarily believe everything my service adviser tells me, he did say that this noise is "normal." Whether it's normal has obviously been a subject of debate on here.

Domm

I think someone mentioned that it was the oil system pressurizing on start up that causes the knocking/some minor shaking. I have this on my vehicle as well for a few seconds on start up. After that, the car runs smooth.

RENNTECH

we have done countless sets of main bearing jobs (in the 200's) to rectify this concern under warranty.

RLE

Who is "we?"

RENNTECH

Dealer. sorry

RLE

How was this approved under warranty? All we hear here is refusals from dealers all over the country and they certainly would not decline a lucrative repair like this if warranty would cover it.

And which bearings were replaced? Rods? Mains? Upper and lower mains or just lowers since replacing the uppers means pulling the crankshaft.

There have been a few (very few) reports of bearing replacements here but when I ask for specifics (what did the R.O. say specifically?) the OP disappears into the woodwork and never answers.

I can't go to my dealer service manager and say "I read on the Internet that somebody's car someplace had a bearing change which cured the problem" without proof they can research is useless information.

BTW, my C300's engine knocks like hell on 90% of starts, hot or cold. It's done this for five years and 36K miles and I'm sick of it.

frogs9497

Someone on another forum posted his MB work order for bearing replacement. I will locate it and post it here, possibly tonight.

RENNTECH

didnt intend for you to go on the defensive? was just stating a fact. my techs would jump all over the car if on start up it had a knock. this repair cannot be an "add on" line and must be brought back in and wrote up as an original complaint. unless the tech is good and has experience its not THAT lucrative. BUT 75% of my techs could do complete main bearing replacement and have car running by the end of the day. Different dealers do different repairs. My original RO line would read nothing more than client states there is a knocking on start-up.

RLE

Thank You.

RLE

I can't be on the defensive since I am not defending anything. You say they replaced all the mains which means to me that the rod bolts must be removed to drop the crank. I do know that all warranty repairs must be OK'd by MBUSA after inspection of the returned "defective" parts or the cost is not covered and the dealership has to eat the costs. That's because in the distant past some techs replaced all kinds of things to increase their commissions and just charged it off to warranty.

frogs9497

Here it is, though I'm just now realizing this was posted in the C218 forum (will try to confirm if this was done under warranty):

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.

RLE

If you read the R.O. posted today by frogs9497, you will see that this car was in the shop for nine days. The engine and trans were pulled and separated and the engine on the stand was disassembled to replace the main bearings. There is no way this could done in one day so we can't be talking about the same repair.

And since a W218 is a CLS, was this an M272 or not?

RENNTECH

OKAY. the engine comes out of the top. no need to pull the trans out. repairs do not need to be pre authorized by mbusa. warranty parts are just held in case they want them back. mount the engine on the stand. split it apart. pull the crank replace the bearings and back together. ive watched it happen. in one day. go to a better shop. total time before car is back would be about 3 days. day one comes in, two repairs done, 3 test drove and back to you

Steve Chandler

Thanks for the feedback, guys. I might try to take it to Mercedes of Escondido to have it checked out. Other than the knock, it is perfect! Just somewhat of a concern for me.