2003 s430 rear end whine coasting@ 55 mph - PeachParts Mercedes-Benz Forum

haYnBenz · #1 01-18-2009, 02:50 PM

Greetings everyone,

So my 2006 S430 was the best car I ever owned. When that lease was up a bought a Lexus LS430 because I thought I wanted more refinement (smoother and quieter at idle).

But I decided to come back to the MB brand and traded my LS430 for a 2003 S430 with 31,000 miles and some cash back. I love my "new" S430 and admittedly was so excited to find a low mileage example in such excellent condition that I did not not test drive it as much as I should have thinking that with 31k miles, everything should be ok.

Well, as I was driving on the freeway I got up to speed and took my foot off the accelerator and started coasting at about 55mph. That is when I heard a noticable (though not terribly loud) whine from the rear end. Under 50 mph and above 60 the noise goes away. I thought I heard it again at about 30 mpg when I was coming to a stop so the sound might be rpm related and not necessarily speed related.

I hoping that the issue is simply with the transmission mounts as I did notice a moderate amount of vibration through the steering wheel and gear shifter when at idle and starting off at low speeds. At first I thought I was just being overly sensitive because the Lexus was very smooth in this regard, but don't remember as much vibration in my '06 S430.

Could it be that with age and lack of use the transmission or engine mounts have hardened and are causing the vibration and rear end whine?

Could it be an issue with driveshaft bearing(s)?

When I hear the whine, there is never any vibration or ride issues so I don't think it is the tires (matching Michelins with 80% tread left). The car does not have the AMG/sport package (which my '06 did and that car had a much "stiffer" ride than this one).

Overall, this is not a huge problem since the vehicle is absolutely incredible in all other repsects and I am glad to be back in the brand. The only reason why I am raising this concern is because my commute to work is 90% highway and - you guessed it - 90% cruising between 55 and 60 mph. Doh!

I hope this can be a quick fix. The B service is due in 7,900 miles if that makes a difference. The previous owner was the Ritz Carlton on Maui and there isn't a MB dealership on that island so I am unsure who serviced the vehicle. The car is now in Honolulu. I have not had the time to take the car to a mechanic but will once I can find a good independent garage.

Thanks in advance for your help!

Pooka · #2 01-18-2009, 07:24 PM

Only a real mechanic hearing it can say for sure, but it sounds like a rear-end problem as in the ring and pinion. On some cars this can be adujusted by shimming but I am not sure about this one.

The carrier bearing would make more of a thump-thump noise.

haYnBenz · #3 01-19-2009, 04:56 AM

Thanks for the suggestion, Pooka.

johnathan1 · #4 01-19-2009, 05:38 AM

In my experience, bad carrier bearings usually just cause a vibration and don't actually make any noise when they go bad.

But the noise while decelerating definitely sounds like the rear-end/differential to me. Check to see if it's leaking at all...that should give you a clue.

WINGAS · #5 01-19-2009, 10:03 PM

And it **could** be a tire. You;d notice the change in source when the tyres were rotated. But I would check fluid level first.

amg280 · #6 01-23-2009, 12:17 PM

Sounds like a common diff problem. cheapest way out would be to get a used one from a salvage yard.