ealarlington

I just purchased an '05 C55 from a pre-owned dealer with 40,000 miles. When the car shifts between 2 and 3 gears (between 2500 and 3000 rpm's) I hear a pinging/knocking noise from the engine. The dealer states "this is normal for the AMG engine with 40,000 miles on it".

This is my 3rd AMG and I have NEVER heard this from my others and furthermore, I doubt AMG and MB would design/sell their high line performance cars to only have a normal working shelf life of 40,000 miles. I cant imagine if you ever asked one of the AMG builders if this is normal, they would say it is.

Has anyone ever experienced this pinging or knocking noise from their AMG?

JToups386

"Pinging" or "Knocking" is also known as "detonation", which can be caused by a few factors.
1. Low octane fuel on a high compression engine. (like your C55 which has an 11:1 compression ratio engine)

2. Too much air and not enough fuel. (typically from a supercharger or turbocharged application, which doesn't apply to your C55)

3. Bad gas. (low quality fuel from a non-branded supplier. I recommend sticking w/ Chevron, Exxon, Shell, BP, etc. Don't use private sellers that can purchase their fuel from any cheap supplier.)

4. Spark/cam timing being off. (not likely in your case since it's completely controlled by the ECM, and cannot change itself unless you've had it re-programmed.)

My first inclination would be that you're getting bad gas somewhere, or you're buying a lower octane fuel. The AMG cars should only run 93 octane premium --- no exceptions.

How much knock are you hearing? A couple of "pings" at the top of a gear change under wide-open-throttle are not uncommon on a performance application. On my turbocharged Grand National I get a couple of "knocks" on the 2-3 shift under WOT. I also used to get an occasional ping on the shift in my 11:2:1 compression LS1 stroker engine when the weather was very hot.

Again, my first suggestion would be to buy premium fuel if you're not already. You might also consider adding some octane boost and fuel injector cleaner for a few tanks, just to see if it clears it up. If none of these options work, then it's time to go back and have a more stearn talk w/ your MB dealer, and explain to him that your $60k car is not "designed" to do that at 40k miles, or even at 100k miles.

Brabus C55

I've heard what I believe to be "lifter tick" ... a "tick-tick-tick", not a "knocking" which you can hear (& sometimes feel ... a bit like a tiny shudder).

Is it a "tick" or a "knock"?

mkonei

tick-tick-tick every damn morning!!!!! drives me nuts!! ive put about 25k on mine, and it had 20k when i bought it. a noisey top end is somthing ive just learned to put up with. its possible that the last time it was serviced, they used a heavier weight oil than the 0w-40 that should be in there. anything heavier just seems to be too thick on a cold start.

SFML320

Standard prem fuel in the Bay Area goes only as high as 91 octane

tech_frog

No ticky ticky in mine, even in WOT. All I hear is exhaust note.

And rubber......

JToups386

Hence one more reason not to live in CA!

I honestly didn't realize anywhere in the country sold less than 92 octane. Sorry to hear it. Regardless though, I was just emphasizing to him that he needs to be running premium fuel with the highest octane available.

I can't imagine how all the LA elite w/ their turbocharged exotics can run safely on 91 octane? Sad, sad, sad...

Thanks for the info.

lauer87

i just sold my car but it had about 41,000 miles and i never had any knocks from the engine. maybe there was a slight change from the factory on 05's vs 06's

SoCalCLK

I have a 2004 CLK55 AMG which has an engine identical to your C55's, and I used to get the same "pinging" on my car at 3,000 RPM but only at start-up. It would sound like a slight knocking/rattling coming from the front of the car. I did three things which seems to have eliminated the problem:

1) Oil change to Mobil 1, 5w40.
2) Fresh K&N air filters. My car had 31,000 miles on the original OEM air filter. It had sand, leaves, bugs, etc. it needed to be changed BADLY!
3) Unplug the battery/reset the computers.

With the combination of the three (and perhaps the warmer weather we are having out here lately) the noise has gone away. Hope this helps!

Sephiroth

I have the same noise and i have 65k miles on my C55. Its been there as far as i can remember. the sound is worse when its cold out, but once that beast gets warmed up its fine. no problems so far.

I was told by a local euro tuning shop near me that this was due to having forged pistons. They tend to expand and shrink more than cast ones, so they're a bit "loose" when its cold out.

JToups386

This is not "piston slap" he's experiencing. He said it happens on the 2-3 shift.
Is your noise happening only at the shift point, or are you hearing it on cold starts? If the latter, then you've likely got an oil pressure issue, worn rings, or damaged bearings, but I doubt this is the real reason for the noise.
I've built several engines with forged pistons on domestic applicatoins and have never had a "piston slap" issue like that, unless I had severely damaged something internally due to detonating the pistons/bearings.
I think he's chasing a different (more simple) problem per his noise only being noticeable on the shift.

SoCalCLK

I think it was more on the 1-2 shift