Rattle coming from under my B Class

[paulandlouise]

I have a 22 month old B Class 160 sport auto and when I pull away or drive slowly I hear a rattle coming from under the car - I can't see anything loose - the car only has 12k miles on - any ideas out there as we use the car a lot and don't want it to let us down - don't really hear it driving just when idle especially as you pull away - cheers ...

 

[SJX]

Maybe as simple as an exhaust heat shield rattle some where? or possibly a slight misalignment of the pipe and its catching/rubbing some where. Take it back if under warranty let them have a look. Failing that, one of the high street big names will have a look on a ramp for you.

 

[MB-BTurbo]

Where is the rattle? At the front, middle, rear?

 

[JasM]

Just take it back to the dealer, it will be covered under warranty.

 

[MB-BTurbo]

Was there an outcome here?

 

[paulandlouise]

Sorry -car in next week - decided to wait until the service as dealership location not ideal - still a rattle some days worse than others - got me stumped but will update when it's been in - thanks

 

[mightymouse]

might be worth checking if you have any loose items inside the cabin sorry if its too obvious but i gave myself a scare because of some fallen loose change.

Another thing to try is to get someone on the outside listening and see if they can catch where its from.

 

[Dieselman]

Not got a baby with a rattle trapped under there have you? Have a look for pushchair wheels.

 

[paulandlouise]

Well took it to the dealer - full service done - they reckoned rattle was coming from engine cover rubber feet ( I told em it wasn't ! Unless the feet reached under the car where the noise is coming from ) but they replaced the feet anyway - drove car home - rattle still there so back to the dealer next week ! Can't grumble took a B Class in and they lent me an SLK ! Can't wait to take it back in to see what I get this time - will keep everyone posted !! Noise mainly happens when car been standing a while and is started then - not that noticeable after a long trip - feel this is gonna be a tough one to sort !

 

[bing]

When you take it back insist a road test with one of their so called technician. Leaving it there with just words of description is a waste of time - they'll just keep guessing !

 

[MB-BTurbo]

...unless you keep on getting SLKs and then just let them do nothing again.

 

[ccp]

I'm not sure if this is 100% relevant to this thread, but my A150 (09 plate) had a slight rattle from under the middle / front of the car when we bought it 10 months ago (~40k miles) which has now developed into a consistent rattle when the engine is under medium to light load between 1000-1400 rpm. This rattle, to my ear, sounds like an exhaust baffle or possibly a loose/damaged cat matrix.

Its under warranty so has been in to the local Mercedes dealer many times to diagnose and cure the issue, but we are now being told that this noise is a characteristic of the vehicle.

After much too-ing and fro-ing they have exchanged the rear exhaust section (silencer and pipe) with that from another A class and the noise remained. The next step is to remove the cats ( i believe there are 2) for me and their technician to inspect to confirm that they are undamaged.

My question is simple, does anyone else have an A class of similar ilk that makes a curious rattling / exhaust noise under the conditions described above or is it just mine?

I have posted this question in this thread because I believe the A-class and B-class models to be very similar - if I am wrong here I know someone will correct me.

 

[MB-BTurbo]

Yes I had the same. It turned out to be the plastic air intake box vibrating against the frame of the car. I didnt need to take it anywhere though, just lifted the bonnet and located where it was coming from when someone revved.

Can they no locate it more accurately when the car is revved?

I have had many knocking and vibrating noises on my B class. The dealer I bought it from gave up in much the same manner and told me it was the character of the car. Nonsense. I went elsewhere and they were able to locate the noise to be the shocks, got them replaced and the noise was still there...changed the roll bar bush and the noise went away. It is now silent and smooth running, as it should be.

If you are not happy write MB a letter formally stating your dissatisfaction and wait for a response. I would love to see a letter (as would Audi, BMW et el) from them explaining that this is normal for a Mercedes to rattle. The fact that they have heard it, recognised it as not right and tried to fix it shows that they are fully aware that this is not a normal characteristic of the car. If it was they would have said that from the start.

 

[paulandlouise]

Hi - that is exactly the position rev range etc that causes the issue with my b class - it can't be normal as it didn't do it when we first got it - so back to the dealer it will go - I will provide an update when they have had a look .

 

[ccp]

Your comment regarding the noise not being normal is exactly my position. I am taking yet another MB service person (this time its the service manager) for a drive tomorrow night to demonstrate the noise. I will let you know how I get on.

 

[paulandlouise]

Your comment regarding the noise not being normal is exactly my position. I am taking yet another MB service person (this time its the service manager) for a drive tomorrow night to demonstrate the noise. I will let you know how I get on.

How did you get on this evening - I didn't even get the courtesy of a call back from the service team will be ringing them again tomorrow.

 

[ccp]

Didn't get on too well. Went for the drive with the service manager - demonstrated the noise to him and was told that it was definitely a characteristic of the exhaust system and that he can make the same noise happen in other A class cars but at different engine speeds.

I was also told that when they fitted an exhaust from a donor vehicle they also fitted the manifold and CAT from the donor vehicle. If that is the case (and I have no reason not to believe him) then it would suggest that the root of the noise is not the exhaust system but elsewhere which would in turn make my noise not a characteristic of the exhaust system because, despite being fitted with an exhaust system from an entirely different vehicle the noise is unchanged! Confused? I am getting that way...

Despite this, the plan is still for MB to strip off the exhaust components and then for me to inspect them and the car for evidence of developing failures any any other possible source of the noise - this is planned for tonight.

I'll update again tomorrow!

 

[MB-BTurbo]

She rare you based? If I'm near you I don't mind having a sit in the car. The amount of things I have had changed on my b class due to rattling I may be able to assist or at least rule out possibilities.

 

[MB-BTurbo]

Sorry, should have been "where are you based'"? Phone having a predictive text 'mare.

 

[ccp]

She rare you based? If I'm near you I don't mind having a sit in the car. The amount of things I have had changed on my b class due to rattling I may be able to assist or at least rule out possibilities.

Guessed as much I'm near Huddersfield - Yorkshire.

Update from today's visit to the dealer: During the test drive we were told that the complete exhaust had been exchanged for one from a donor car which included the manifold and the cats. But today we learned that the true meaning of this was that the exhaust manifold, cats and downpipe had been replaced with a unit from a donor car, but the rear silencer and tail pipe were the original

Guess I have not yet learned to speak Mercedes... and all the while the phrase "It's a characteristic of the exhaust / vehicle" was repeated.

Tomorrow, the car will be "fitted with new exhaust manifold, cats, downpipe, rear silencer and tailpipe". It will then be delivered to us to test drive... again.

I'm not holding my breath