Hi all,

So, this issue started recently. This is on a 2012 E350. When the car sits for a few hours, and cools down, when you go to start it, you'll hear a loud flapping noise from the drivers side rear motor area. It lasts about 5 to 10 seconds and then its gone. If you turn the car off and on again, it won't do it again. The car has to sit for a while (hours) before it'll do it again. The car doesn't make this sound while driving. Only upon cold start up.

Could it be an air pump? What could cool down and cause that type of noise?

Any help would be greatly appreciated. Its a really loud noise and worries me that it could be something getting worse over time.

Thanks for your help!

 

Any noise under the hood. I have heard folks talk about the wastegate rattle on the forum. I think there is a video that JMG posted. You may want to compare the sound. Not saying that's it.

 

 

Sorry, I had E550 on the brain. Let us know what you find.

 

Sounds like same issue I had with my 2013 E350. I had dealer apply bulletin # LI05.10-P-056435.

They had to install a check valve to prevent oil from completely draining from chain tensioners.

That fixed the problem for me.

 

Wow, that is awesome information. Thanks! We just dropped the car off to the dealer. I did not have time to look into this, and she was tired of hearing the noise. Plus, she was getting concerned it would cause more damage. Once I know what the final fix is, I will post it here.

Your post sure sounds like it could be the issue. Its not really a rattle though, but more of a flapping sound, but I guess it could be construed the same way.

 

My car was making the flapping sound in the same situation you described (cold start, or a start after a few hours of sitting off). I gave the dealer the document, they performed the service, and it hasn't done it since (been 3 or 4 years now).

 

Was the repair free of charge?
My engine (2014 E350 gas) also seems to make some noise after cold start and I am just wondering if the dealer would do the repair at no charge.
Thanks.

 

Yes my car is still under warranty, they did the bulletin free of charge. It did take them most of a full day to do it as there is some disassembly involved

 

Well, just an update. The dealer has had the car for over a week, and could not figure out what the flapping sounds was. They contacted Germany, and they had the shop look at the service on the car for the past year. Very bizarre. Well, they are now saying that the cam shaft may need to be replaced, and the cause COULD be the fact that the Mercedes Indy dealer didn't use the correct MB paper filter. Therefore, restricting the oil to that area of the motor. She did take her car to an Indy for the oil changes, and this shop has been in business for over 20 years and has a GREAT reputation. They service ALL German makes too. I think the dealership is trying to weasel their way out of the repair. They initially said it was covered under the warranty, but Germany is disputing this because of the oil filter. Really???

What do you guys think? Do we have a leg to stand on? They are telling her that it could be $6 to $8k to repair this. Oh, one more thing. The Indy shop, back in April, replaced the Cam sensor to see if this problem would go away. Apparently, the car was throwing a code for this. After replacing the sensor, the code disappeared.

Thoughts? Really could use your opinions on this one....

 

Sounds sketchy to me. If it "might" be the filter then exactly what filter was in it? And if it truly was restricted then it seems other components would be damaged.
Any way to get an independent diagnosis?

 

I just don't think the filter would cause this. If I am not mistaken, the issue was present before the latest oil change. OK, I could be wrong, but I have been working on cars forever, and filters are filters. I realize that each has certain "specs" for what they allow to pass-thru, but most car filters do not obstruct oil passage. They merely, trap particulates, so unless you go way past the oil change due date, and the oil becomes totally saturated with metal particulates or dirt, its not going to slow the oil flow down that much. She was very diligent with her oil changes. Anytime the scheduler popped up on her dash, she would take the car in within a week or so. Before it was even due. During the warning stages.

We shall see how this plays out....

 

Update....

Good news! Dealer called back on Friday, and said that they were able to convince Germany to handle this under warranty.

Bad news: It may take three to four weeks to resolve the issue. Looks like they have to pull the motor to look inside the oil pan and check out the cam assemblies. At least she has a rental car during this.
I'll keep you guys posted as to the final fix.

 

Next update. Hope this is OK. Don't want to eat up space, but thought this was incredibly cool of MB to work this hard at customer satisfaction.

Looks like the dealer opened up the motor to work on the CAM assembly, and the noticed one of the cylinder walls is scratched. I'm assuming they are expecting some blow-by to occur there. Though we never saw any smoke out of the motor. Anyways, they are contacting MB Germany to get authorization to replace the motor. This blew me away, and I still can't believe they would do this all under warranty. If they do replace the motor, I will be blown away, and will be one of their biggest fans.
I'll keep you guys posted!

 

So, the flapping noise is from the cylinder that has scratches ?
Did MB dealer specify what caused the flapping sound ?

As i know, this flapping sound with cold start, usually is piston slapping. This is top end noise.
Engine Internal damage might be there already.

 

-----------
No, the flapping was supposedly from the cams, but during inspection of the motor, they noticed the cylinder wall was scratched and should be re-worked. Hence, the motor replacement. We shall see how this goes.

****Update*** MB dealer is waiting for the new motor to arrive. Talk about great customer service. My only reservation is, now the tranny and rear end have 100k miles on it. How will these items mesh over time.

 

Well, the car came back late last week and the new motor is in. I read the service report, and the initial find was a bad CAM assembly, and during their troubleshooting the dealer found the #4 cylinder wall was scratched up pretty badly. They sent the report to Germany requesting a motor replacement "under warranty", and after some conversations between the dealer and Germany, the motor was shipped and replaced. If this doesn't boost your faith in MB service. I'm not sure what would. She did purchase an extended warranty, but I wonder if this fell into some "other" warranty tied to the motor.

Anyways, the flapping sound is gone and the car appears to run fine. They did give her a one year warranty for the work. I'm guessing this is for the labor and associated work.

 

I'm glad this worked out for you!
As far as tranny, diff, etc, they won't be affected by new engine - it's not like your installing double the hp or something. If they are fine they will be ok, if they were developing an issue over time, it will still happen. I would suggest tranny filter/fluid change and diff fluid change though if you have not already done so.