DouglasKing03

My 2001 S430 will make a popping sound when I come to a stop after the car has warmed up. Only occurs when car is between 3/4 full and about 1/8 full. Dealer has said its the charcoal cannister and that its "normal." Ain't now way in hell it can be normal or they would never sell one of these! It's random, pops intermitantly and several times in a 15 second period. I am not sure if its what they think it is, as they probably haven't spent much time with the car - but it is driving me nut and I will sell the damn thing if I can't get it fixed. Car has 53,000 miles on it and has been to the dealer twice for the problem - once at 44,000 and once at 49,000 - same result - "it's normal." Any one else have this? Any ideas?

jahummer

What part of the car is the "popping" sound coming from?

DouglasKing03

It is coming from the trunk area. It sounds like someone is trying to get out of the trunk. it's a strange, strange thing.

saturnstyl

Some cars are worse than others, I would try to get the charcoal canister shut off valve replaced. This is not common on an S-class, after at least attempting a fix it would be acceptable for them to say it cannot be fixed. There may actually be something about your particular car that makes the noise more prominent than in others. Some folks are just more receptive to noises than others. Maybe they really can't hear it, because to most people it is very faint. Some noises that have always been in cars are just now being noticed by people because the cabins are better insulated, and the mechanical noises are being reduced to the point that now you can actually hear these sounds. If all else fails, take advantage of the bose audio system.

DouglasKing03

I had wondered if it were only me, but with the radio on, I have asked my passenegers if they hear that sound and they say "the sound like someone is trying to get out of your trunk?". It ias a loud as someone rapping on the trunk with the knuckles trying to get your attention. The Bose only barely coveres the sound. I just don't understand why the shut off valve would need to shut off randomly and 7-10 times in a minute. I wondered why they did not try to fix it under warranty - usually they jump at the chance to fix warranty items. So no one has heard of this as a big problem on other S Class cars? I think they jsut didn't spend enough time in the car to hear it well enough - it needs to warm up first.

saturnstyl

Well, we don't exactly "Jump" at the chance to fix warranty items. Warranty pay is less than acceptable to put it in nice terms. Warranty pay and a vacuum cleaner have something in common if you catch my drift.....
That canister shut off valve can be a real pain to get at sometimes, but since you describe it as being so loud, I definately think they should change it out and see what happens.
Keep in mind that Mercedes isn't always forthcoming with information. Sometimes we can't find work instructions, diagnostic info, wiring diagrams, etc... And we are the DEALER! Sometimes we fly blind and figure it out as we go. That takes longer and we lose money that way. Point being that I for one do not even know the strategy Mercedes uses to activate that valve. I know its there, I know what it does, but as for exactly when and why they do it that way, I am clueless. Sometimes they thump, if its loud, it should be replaced and then see if the new one is any better.

Sometimes working on mercedes is like

DouglasKing03

Thanks for the information. I will push a little harder and if they ca fix it, I'll go back and try to get it under warranty from MBUSA. I appreciate the help!