K-A

My car has this "clack clack" sound, at least sometimes when it's cold, and at idle. It literally sounds like an on again-off again diesel-y sound, when it "comes on". I think it goes away after some time (have to analyze better), and know I hear it sometimes, and sometimes it either doesn't, or I'm just not listening for it.

I'd say it would appear to sound like piston slap.

Someone with an E550 posted a similar symptom in another Message Board, and said he took it to a Dealer, and the SA said it's a "normal thing for an M-B motor". The poster then compared with other E550's and said he indeed heard the same sounds, so his mind was put to ease.

I'm wondering, is this something normal? If anyone can put their ear to their grille when their car is at idle (preferably cold), it would be appreciated!

220S

One will never know if it's normal until the engine goes. Remember the GM "piston slap" debacle? If the dealer is confusing tappet noise versus piston slap, than that's no big deal as all these motors make valve train noise esp when cold. But tappet sound is high pitched clicking in fast succession whereas piston slap is kind of slower and can sound more erratic (not all pistons are hitting against the cylinder wall), and very much diesel-like in sound. Both go can away after warming up (esp piston slap as the pistons heat up and expand against the cylinder wall.)

Piston slap is either from high mileage or mismatched pistons and cylinder bores at manufacturing, so that rules out the former for you. Just curious, did you change out your break-in oil early on or are you still running on the factory fill? What's your oil consumption? How much did you use until your rings were seated, or are you still using oil? Break-in is around 15k (at least on the 6.2 liter motors.)

Make a recording and post it here. Piston slap is not 'normal' with any motor.

RNBRAD

I always thought that on my e320, specially at start-up, just has that slight subtle diesel knock to it. I'll listen to my 550 closer next time I start it cause I don't recall it making any sort of sound. Maybe I'm just use to it I dunno. I'll pay closer attention next time.

kingofire

I had noticed the cold knock when I picked up my car as well. I don't like to keep the break-in oil for too long in any of my cars for more than 1000 miles so I ended up changing my oil to Royal Purple oil 5w40 and I ended dumping in 5oz of Red Line's Break-in oil additive that has tons of ZDDP(anti-wear additive) that plates to the metal parts of an internal combustion engine to decrease wear. This has eliminated my knock for now.
Another great product that I have used to eliminate knock especially piston knock is Lubro Moly MOS2 oil additive. MOS2 is Molybdenum disulfide which is an anti friction additive that some oil companies use. I personally am a huge fan of Moly because it quiets an engine considerably and really helps with idle knock and vibrations. If the knock bothers you, then try Lubro Moly MOS2, I have and I absolutely love their product.

ttoE550

I walked my dog this evening near a stop sign at the bottom of a hill. A *C* 350 stopped, and accelerated up the hill. I heard a sound that was "diesel-y" that I would not have noticed had I not recently read your post. I don't know what produces the sound, but I've heard it many times before. My wife's former BMW 330i gave the same sound. I would guess it is normal.

That being said, I've experienced "piston-slap" depending on gas stations I use, but on different cars than my E550. I assume you are using the correct octane level recommended by MB for the 350 engine. But refueling at discount fuel stations and ones that are less or more busy can also cause problems. At discount stations, you get what you pay for (see a recent thread on this matter). At less busy ones, the fuel can be "stale," and at busier ones you might be fueling with gas that is at the "bottom of the barrel" and contains sediment, etc. Maybe try a different station, or pay attention to the refilling dates.

But really I have experienced zero piston knock on my E550. I love the sound of my 550 (but I love the sound of the E63 more!), and start it in a garage where every sound echoes, so I would have noticed.

K-A

I've got about 4200 on the car right now (Mileage), and am still using the same oil from the factory (no services yet to the car, bought 6/2010).

I haven't checked my oil yet (should remember to do that), but so far, no I/C Messages or anything.

Also, I do use the recommended 91 Octane, from Chevron or Shell, or 76, as much as I can.

The best way I can describe the sound is like a little "clack clack clack", not really slow, but not a very rapid sound either (although siding with quick over slow). I'll try and Upload a Video of it asap. I'm starting to just think it's a normal noise, considering I've heard people confirm they've heard a similar sound, like ttoE550 did with a C-Class on the road.

If anyone has any other experiences with it, please do share! Also, just fyi, the sound doesn't come from the exhaust, just the motor, and can be heard best right at the grille area.

ash_cpe

Interesting, It became brutally cold now "27 deg F" and I have noticed this sound this morning while coasting to a stop sign by my house, it went away after about 1~2 miles of driving. My recommendation, try not to floor it for the first 5 miles after cold start. GL

RJC

Type of air pump mb uses makes this sound, open the hood before cold start or when you hear the noise then start moving your head around the inside of the engine compt with your ear close to the fenders and you should locate the little pump; it's normally on the drivers side, it's small and mounted on rubber iso mounts

GuyFawkes

I noticed my E550 makes that noise too once in a while. Maybe cold weather related?

RJC

If the rate of clicking does not increase with engine rpms, it is the air pump I mentioned above...

K-A

Ah, good test. I'll check and see if it increases with the motor RPM's next time. If not, I'll look into that air pump.

So if it's the air pump, it's "normal"?

RJC

Yupper

Yaya_B

Hi All,

I'm new on this forum. I don't know if we got the same problem but I do have a diesel-like noise at idle.

I could hear the noise "clearly" by opening one of the front doors and lower my head down.

I got a dealer visit on next week to check this out.

In the meantime, does anyone have the same problem?

K-A

Sounds like what I was describing. Please let us know what the Dealer says. From what I've gathered, it seems to just be the nature of the beast.

WGB

My 2003 211 E320 with the M112 engine had an awful amount of piston slap when cold from new which was transmitted up the gearbox mount into the cabin. After several complaints and a letter to M-B Australia I found out about the US M113 (E500) engine mount replacement program which was being performed in about 2003/4 due to transmitted noise into the cabin.

When I reported this program to the local agents I was asked to book my car in and I picked it up later in the day. Apparently the diesel engine mounts were fitted and the car was perfectly quiet for the remainder of the four years that I owned it.

My ML 500 with M113 5.0 litre 3 valve V8 had a large amount of piston slap type noise when cold which was not audible in the cabin but could be heard when I climbed out to open the gate at the end of our driveway. The noise would disappear in a few minutes during warmup and the engine had no problems nor consumed any oil in the 76,000 km I owned it.

My E500 (E550) with the M273 motor is blissfully quiet when cold inside and outside the car.

I assume the M272 350 motor has balance shafts and these may make some noise when cold.

Bill

BPhillyBenz

I took mine into MB a few weeks ago with what I described as a "valve tapping" kind of noise. I was afraid I Red Lined it too much with the Paddle Shifters...I kept thinking
"f%^k, I think I screwed my car up with only 8,000 miles on it". Turns out everything is fine and "normal". I still am not a fan of the tapping, but I guess it is what it is.

EmE247

Ya i hear a slight ticking/clacking sound after startup on my car as well. Can only hear it when outside the front of the car when the engine is on.

K-A

Yeah, that's how mine is. Seems normal. Maybe it goes away with time.

WGB

It might be possible in warmer climates to use a slightly thicker oil than what is regularly used by M-B dealers but I think the noise is a characteristic of the breed.

Mind you if you want real cold engine noise try an ML 270 five cylinder diesel with a bit of mileage on it - we affectionately called ours the No 9 Bus.

Bill

MatOhio

Mine has 12K miles and has the same thing but only seems noticeable at idle. When first started, and the engine idle is higher, there is no noise, not this one, anyway. Once the idle drops back to around 600 rpm (aprox 5 minutes in my 38 degree garage) it starts the erratic clickety clappity noise. After fully warmed up the noise is faint, if anything at all. I recorded this http://www.youtube.com/watch?v=6dkxZhr84ks this morning. Any thoughts/comments welcomed.

ImInPA

The sound K-A originally describes is most likely the fuel injectors. Many fuel injectors can make quite a racket, especially when cold. I have heard them sound like a very light "diesel" sound as well as sounding like a noisy lifter or sticking valve. High tech isn't always comforting.

OAG

I noticed that the engine is noisy when cold and first starting it up but it then becomes very quiet after about a minute or so. It is a E350 4M 2010 Build date 2/2010. Original Oil (just changed on 3/1/2011) and only 5K miles. I only noticed it because I put the car on the driveway with the garage door open and I was in the garage - now I have gotten used to it and just ignore it (especially as it gets quiet in a minute or so. Opps did not notice this thread surely it has been OBE by now for K-A.

petee1997

My two E's are a little noisy when cold but quiet down when warmed up. In the BMW manual and Porsche also, they recommend to drive the cars as soon as started to get the oil circulating. You should not warm up engine at idle. It will not get proper lubrication.

220S

Correct. Just keep it around 3k rpm or under until oil has reached operating temp (btw, the AMGs have an oil temp readout number in degree Celsius on the IC and it will keep flashing on and off until proper temp is reached...)

K-A

Interesting. So it's not good to let it sit and go to the proper rested idle level (like 30 seconds)? I usually try not to run it while it's still in its "revving" state.

I haven't listened for mine in a while (hopefully it's gotten better with more mileage) since I was told it's normal. However, if I remember correctly, mine sounded/sounds very similar. Also on browsing the BMW Boards, I saw some guys in new 528i's were saying their cars had that same Diesel-clack sound. New engine tech or something I guess (injectors, etc. I dunno).

If you listen very closely when it's quiet outside and inside your car, and you hear that same firing order of the clack giving of a faint "squeek/tap" inside your car?