From inside the cabin, even in the driver's seat, I could hear the sound of fuel sloshing in the fuel tank. It's even louder in the rear seat, and my passengers have been pretty amused! The slish-slosh sound is very apparent from a full tank right down to 1/5 tankful of fuel. I could also hear the return fuel sloshing back into the tank. No, my hearing is not exceptionally good, just normal. :)

Is this normal, or does this point to something undesirable?

Any advice is appreciated, thanks!

Mervyn
1983 W126 (280SEL)

Maybe not your fuel tank...
 

I used to have the same problem in another vehicle (not a Benz). The noise was most evident when stepping on the brakes and it sounded like water was slushing around and rushing forward. Apparently, it was water in the channels in the door frame/floor where the wires normally go. Water was seeping in whenever it was raining hard or whenever the car was washed thoroughly. Sealing it properly eventually solved the problem.

You might want to check that out.

You do realize that the gas tank is right behind the back seat? From the trunk, you can pull back the lining at the front of the trunk area and see it. That's why the sound is louder from the back seat but, I don't know why it's making that noise.

Intruder

You don't mention what vehicle you drive, but, I have noticed the same sound from my 85 300D. In my case it became apparent only after I cut a hole in the rear deck to install a subwoofer. The diesel has this strange plastic tank, which is only an inch or so thick and lies horizontal to the rear deck, it's not the main tank.
I've never bothered to find out what this is, but my sloshing sound comes from it.

My solution to the problem...crank up the tunes. :cool:

Is the horsehair or whatever that MBZ uses to pad the back of the rear seat still intact? It also acts as a sound insulator. My old 240 lost a great deal of it over the years and had to be restuffed.

I have not checked whether the horsehair (or other insulation material) is still there, and Rainmaker, I'm very sure it's not water that is sloshing, it's fuel! :)

I guess I'll go stuff some insulation material in the back seat, and if the sound still persists loud & clear, I'll just leave it as that. It sounds embarassing, but if the car runs fine, I suppose I'll resign myself to it.

Thanks for your comments!
:)
Cheers
Mervyn
1983 W126 (280SEL)

My 126 had similar sounds most apparent when tank was full.

I guess this was because I had the rear board cut to make way for speakers, and thus left some gaps for the sound to run through - just as what Merv described.

What I did was to remove the rear seat altogether and added wool insulation before installing seat, and then got someone who did interiors to measure, cut out and design a rear board cover made of wool-like fabric with added insulation. During the course of putting in this cover, we figured that this was where the noise was most apparent.

Now - I don't hear a thing - even without the stereo.

Rainmaker...re sloshing sound:
I have a 98 E300D and have had several quarts of water retained in the rocker panels below the doors... esp following a heavy rain. What I did was to pull out a rubber drain seal on the underside of the rocker panel draining all the water. Had to do it on both sides of the car. The rubber drain got clogged and all the water sloshed around heard when stopping quickly. Cure complete. RSL