2013 C250 Sedan engine rattle/knock
 

I have a new 2013 C250 sedan (luxury package) that I picked up about a week ago. I have been noticing a rattling in the engine that sounds like a ball bearing in a spray paint can when I accelerate.

This was very noticeable the other day when I was trying to pass another car around 30 miles an hour. The dealer told me that they fill up the cars on the premises with the proper gasoline, but it sounds to me like bad gas causing engine knock.

Also, I know what the turbo is supposed to sound like, so I can discern that the sound I am hearing is not turbo related.

I am bringing the car in to the dealer tomorrow since the power seat and steering wheel no longer operate (probably a blown fuse, really!!!!)

Has anyone had any similar experience.

Yes, I have had a similar experience with my car. When I bought the car the salesman told me that I can run 87 octane in it with no problems ( mine is a C300 btw, not a c250). They filled that tank with what I assume was 87 octane gas before I went to pick it up. It sounded exactly the same as your car sounds. Horrible rattling and chatter when accelerating. I drove around a lot the next two days and emptied my tank as fast as I could. I filled it up with 93 octane and let's tell you it was a completely different car. Not a single rattle from it now. Use premium gas only and it should take care of your issue.

Thanks Cleanbenz. I have used a little more than half of the original gas that was in the car when I got it and my plan was to use it all up completely before refilling with premium fuel. I suspected the same as what you described. That the dealer filled up with the wrong gas (probably intentionally to save $$$). To test the theory, I will probably just drop the car off to have the seat fixed.

It just frosts me that the dealer would want to foster customer dissatisfaction right off the bat with a new car purchase that they would cut corners to put cheap gas in the cars.

Shame on MB for cutting corners on such a simple thing like putting the correct gas in a car! Do they do the same for oil changes too?????????????

I just bought my wife a new Lexus RX and suspect the dealer did the exact same thing. I didn't hear any noises from the engine, but the salesman told me I could run 87 gas. The manual says otherwise.

Irritating, no doubt.

My dealer did not say anything about using 87 octane. The service advisor on the phone got defensive when I suggested the noise might be caused by using the wrong gas. To put his money where his mouth is, perhaps I should ask the advisor to see this mythical "fountain of premium gas" they have on site and ask them to drain and refill the tank with what I thought I paid for in the first place!!!!!!!!.

This is why I never trust sales person (I was one myself) they often tell you only what you want to hear and often lie to get the sale. That's why I always do research online before going in there. Person without knowledge is always an easy sale because they believe in whatever you tell the person

Brought the car in today and went for drive with technician. He hears the sound and tells me that it is due to the direct injection system and the opening and closing of valve cylinders. I don't believe it. I left the car and took a loaner C250 of the same year and drove to work. Guess what? No rattle!!!!!!!

So, the question for you MB is this, if a tree falls in the woods and no one wants to acknowledge that it fell, has it really fallen? I'm getting really annoyed now, as you can tell.

It is undeniably valve tap due to crap gas. I'm telling you I went through the exact same thing. Don't listen to these liars. Direct injection has nothing to do with any kind of rattle from the motor. I can't believe they even said that to you. I guess they are trained to have a logical solution to every noise the car can make as to not incrimate themselves in front of you.

One of my friends worked for MB as a technician for many years, when he first got in as a noobie, one of the senior technicians told him to not bother changing the oil filter on some oil changes to save time... I've heard same stories from BMW technicians as well.

which year RX? I have a 2004 and I put 87 in it with no problem. That engine doesn't need high octane gas.

2013

The tech may not be all that wrong as far as a characteristic of the engine. I too noticed what I can describe to be a "wobble" sound of the engine during certain engine load/acceleration. It seems more prevalant under "E" mode and when you're doing modest acceleration but the tranny doesn't downshift because its in the sluggish "E" mode.

I rarely encounter this sound anymore. This could be due to one of a few reasons though. It seemed to go away after 2,000 miles or so (out of the break-in period). Around that time I also started to switch almost religiously to "S" mode upon startup. Additionally, I also had installed the Burger Tuning Intake and Tune...

I usually know more about the mechanical functions of the car before I assist or do the buy myself. A real knowledgeable sales person is a rare find.

I thought that there is a law in the US that all gasoline consuming cars must be able to run on 87 octane fuel. But it's ok to require a higher octane for normal use. For the 2008 C300, I think that octane is 91 pump octane. The owner's manual should specify what the C250 requires for normal use.

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saga ongoing
 

Well, here is the update, and it's not promising.

I completely refilled the gas tank with Chevron 91 pump octane, which is the highest octane you can get in Southern California (I was told). I drove the car for 250 miles and have not observed any improvement in the knocking sound.

I called MB corporate and opened a case with them and they told me to keep refilling the tank with premium to take that out of the equation, even though the car has a knock sensor that should allow the car to run (albeit with less power) with 87 octane without pinging. They said to keep using the car in the break-in period (~1000 miles?) before calling back to complain.

I'm not pleased since even the dealership confirmed that on a bunch of the loaner cars they tested, the volume level of the knock they observed varied widely and no understanding of the cause has been identified.

MB corporate is also knows about the problem but they don't have any solution other than break in the car. To me the sounds sound like something is quite wrong and cannot be fixed by running the engine. At some times it sounds like a loose chain running against a rail or something.

I would gain another opinion from an experienced MB mechanic.

Ask him what is causing it & where it is coming from.

If the noise is as bad as you say it could be doing irreparable damage.

Good luck.

I took the car into the dealership I bought it from and did a test drive with the shop mechanic and the car was left for the day with the shop foreman. I don't know how much more experienced I can find on the short amount of time I have to deal with this problem.

If I take it to a non-warranty MB mechanic, they will most certainly be looking for work to do at my expense. There lies the catch-22.

I will probably take it to the next closest MB dealer to be looked at.

As there is a fake "gas crisis" in California, prices are over $5 for premium. It is just gouging. Some gas stations are tempted to put 87 octane in the premium pumps, and there are lots of complaints about pinging on other websites. The MB dealer is just flat WRONG, this car requires premium gasoline, remembering that in Europe the gas is much higher quality as well as price! The premium gasoline requirement is right there in the owners manual.

I sometimes put 103 octane in my San Diego-based V12, and many places have 92 and 93 octane in SoCal. Costco seems to have the best and lowest-priced premium, although many locations are currently out of fuel. You can always try Sunoco 260 which is 96 octane. If your engine makes noise with Sunoco 260, then it sounds like an improperly functioning turbo gate, this should be accompanied by poor MPG.

The MB dealer should look at any error codes, although most other threads describing this problem in the C250 are resolved just by filling the tank with quality gasoline from a reputable vendor.

Thanks Acapulco Bill. Actually, I was wondering about the gas mileage aspect to this, because I have not been getting close to the sticker mileage of 31 mpg highway, which is what I drive on most. I am getting around 22 mpg with the possibly fake 91 octane from Chevron. Could a turbo gate be defective in a car that has only 500 miles?

The dealer claims they checked all of the error codes when I left it for the day. Would the defective turbo gate come up on the scan?

It is doubtful that the gate mechanism itself has a detector that would throw an error code, however some other codes such as lack of pressure from turbo boost should have come up, as it is essential to have that value for the ECU.

Such poor highway mileage could indicate lack of boost, and as the ECU would cause the injection of extra gasoline due to highway engine speeds, the pinging could be a result of this excessive gas mixture, especially if the octane is low. The 1.8L C250 engine by itself has a 9.3:1 compression ratio, not very high as compared to the BMW 328i with a 10.1:1 compression ratio which is a reason for its 240 HP.

Besides the gate, if the noise is a constant rattle and not a sound like marbles inside the cylinders ONLY upon acceleration, the actual turbo bearing could be suspect. This would have the same effect of low gas mileage, although with just 500 miles on the engine, you should give the engine break-in to about 3000 miles to really get an accurate MPG figure

Still think however that octane is the issue, a half-a-tank of of Sunoco 260 should give an indication within a few miles driving.

Thanks. There is only one station still left that sells 100 octane unleaded fuel. I found a blending chart online so I guess I can try to mix it at the pump with 91 octane to put the fuel quality issue to rest. At $10 a gallon for 100 I hope it's worth it!

My 2006 Audi A4 2.0T is turbo charged and direct injected like your C250 and it absolutely is a strange sounding engine compared to my NA non-direct injected engines. It sounds very diesel like at low RPM's and it chatters but ive never heard a definitive knocking. I would definitely let the engine break-in before you start complaining to MB. Engines usually do strange things during break-in and then sound/act normal was everything is worn in.

I filled up the tank with full tank of 91 from Costco and today...NO knocking or pinging sound!!! This is a big difference from the last time after I filled up with 91 at Chevron.

Now that I think about the dealer's comment about how some of the loaner cars have varied levels of the same pinging sound in their C250 fleet, it make all the sense in the world because they rely on customers to fill the tanks when they bring the cars back. I assume that most customers are going to put in the cheapest thing they can, while others might actually do the right thing and put in premium. The end result however, is likely varied levels of engine knock depending on the resultant octane blended in the tank of each car in their fleet. Therefore, comparing what my car SHOULD sound like to a fleet of unregulated loaner cars is simply, in my opinion, WRONG.

Anyway, my car (at least today) finally sounds like I think it should. Should this continue, I will continue to keep filling up at Costco, as I do with my GL450. For now though, it appears that the bad gasoline (hopefully that was all it was) has run its course.

Well, I spoke to soon. After 1200 miles the engine knock/wobble is back. Took the car to another dealership and they flashed the engine ECU since a TSB came out in October. This didn't have any impact on the sound. Now my wife is driving the car she's complaining about the sound. MBUSA and the dealerships say the sound is normal, but this still sounds like a sewing machine on wheels. I'm getting kind of fed up with the dealers looking at me like I'm crazy. MBUSA won't do anything unless the dealers confirm a problem, which they won't do because they don't know how to fix the problem. Now I'll think twice about upgrading my current GL with the new one since the new ones have a "direct injection" setup as well.

Is this the same sound you are talking about?

This is normal sound, you can kinda hear the rattle:
http://youtu.be/6OUjn53wLjU

This is the full blown on rattle sound:
http://youtu.be/xoszS7-Dnao

I need to have this looked at by my dealer.

DI engines do sound different.

They need to check that the ECU tune can retard timing adequately at the onset of knock detected by the sensor.

Other causes of rattle can be the timing chain & tensioners & the cam adjusters.