miguelcarlos

I finally got my car back after 7 weeks in the shop for the knock at start up issue I was having. Seems the bearings had too much clearance from when they were initially installed from the factory. They tore engine down and bearing measurement wasn't correct so they replaced the bearings. Have had it back for 2 days and haven't heard the knock. i have been an Audi owner my whole life and I have to say I'm very disappointed with my Mercedes. it has been in the shop longer than I have owned it. I'm in the process of trying to work out something with MBUSA on this lemon vehicle. All of you out there that have this issue and the dealer says it is normal IT IS NOT- It is a bearing clearance issue. I'm sure there are lots of cars rolling around with this problem!!

Acapulco Bill

Too bad, my C300 starts so quiet I force myself to wait the couple of seconds until the tach kicks in just to make sure. Too bad the repair took 7 weeks. A thread with lots of posts and thousands of views on this issue:

https://mbworld.org/forums/c-class-w...ine-noise.html

C300Kid

If it's been in the shop once for one issue how is that a lemon? Just seems like the dealer couldn't figure out what the problem was.

Sorry about your inconvenience though.

RLE

I asked you this question a long time back and you ignored me.

How was this authorized and by who? Is there a TSB covering this?

None of the info to date is of any use to the rest of us with startup knocks unless the we can prove that it has been a warranty repair somewhere in MBUSA's territory. The rest of the world's experience is irrelevant.

ergon

Amen RLE. I've got it too.

SuPER__S

I have the knocking too on start up...........

jctevere

Same here. I thought we all chalked it up to low oil pressure at startup from some specific part being too small (the fix is to install a bigger part but I don't remember the name of it off the top of my head). But apparently it wasn't serious or harmful.

If what you are saying is true this could change a ton of things... But the weird part is I don't get this knocking when I use 0-w40 oil, only the 5-w40, which leaves me to believe it is the oil pressure and not a bearing issue. Perhaps you have a different issue all together. Is it more like 3-4 knocks that go away instantly as your car engine turns over, or something else?

EDIT:
Actually, it turns out that guy did in fact say it was a bearings size issue too. Here is his quote:

"The dealer says its normal because Mercedes tells them to say its normal because no harm is going to be done to the engine its just an annoying noise. The knocking sound is from the upper main bearings, theres not enough oil pressure built up during the first couple seconds of startup. The fix is to remove the old bearings and replace them with one size bigger bearings to help build pressure as soon as the engine starts. Ive heard this noise in several 204's including a 2011 with less than 5000 miles on it that I fixed last week by replacing the bearings. Im just letting you guys know what ive done to fix the problem.."

Red_Demon08

i got the same problem but mine doesnt happen all the time.... it does happen often tho

MBDK

Mine just spend the night at the dealer from Wednesday to Thursday as it only happens when the engine has cooled for 6-7 hours. I was sure something was wrong, as it just sounded way off.

I made a recording of the sound before it went to the dealer. You can get it here: https://rapidshare.com/files/1794267..._and_7_sek.wav

Conclusion was that is a "normal" oil pressure "issue". The salesman started up another c180 for me and sure enough, the knocking was there.

Glyn M Ruck

I'm pleased you have got it sorted. Nevermind what dealers might say it is not normal & can be remedied by Plastigauging the bearing clearance & fitting appropriate shells or small end bushes.

This noise should not be confused with chain or cam adjuster rattle until full oil pressure is attained. That should not happen either apart from possibly at oil drain but that is another matter.

miguelcarlos

I have documentation of repair order stating incorrect bearing clearance from my MB dealer where service was performed (Pittsburgh, Pa market).

bringtherain

came to the dealer at beshoff for this and a balancing issue and they told me it was normal. now i gotta go back. great.

MBDK

Hi MiguelCarlos

Is there any way I can have you upload this documentation, so I can take it back to my dealer? I would very much appreciate it.

Les-10

I agree. I would like to get hold of some documentation as well.

ergon

I took mine to the shop yesterday. I called a moment ago and they said they couldn't hear it. I'm 63 and mostly deaf, war's hell, and I can hear it. If it lets go someone for sure will hear it.