sdunham

YOU DON'T HAVE TO RUN SAME SIZE TIRES/WHEELS ALL AROUND ON A 4-MATIC... AS LONG AS THE OVERALL DIAMETERS ARE CLOSE (1% OR SO) THERE ARE NO ISSUES... I JUST RESEARCHED IT AND AM RUNNING STAGGERED ON MY 05 4-MATIC WITH NO PROBLEMS... VERIFIED IT WITH THE DEALER SERVICE MANAGER AND MASTER TECH ...

Also, I have the "deadbodyintrunk-clunk" too... Haven't dealt with it yet as I also am having a "visit workshop" airmatic issue and "key not recognized" Keyless Go issue at the moment to fix...

crazypotato

Hey, I think I have the answer to it. I was told it was the subframe bushings by some stupid shop. I finally nailed it. It is the fuel tank being loose. PM me if you want some more info.

GT-ER

I have this noise in my car...ONLY when going over speed bumps. I've checked my rear suspension and my subframe bolts with negative findings...maybe it's time to check my gas tank.

crazypotato

The gas tank is under the rear passenger seat. It is cover by 2 under body panels. The tank is held by 2 brackets. It is not hard to bend it. I can do it with my hands. I am serious!! Now, imagine around 65lbs keep banging it each time you hit a bump.

GT-ER

So the problem is not the brackets comming loose, but rather them stretching or something?

I hope this is my problem because it sounds like an easy fix and the sound appears to be comming from underneath the car, not just the trunk it's self.

crazypotato

Mine was deformed. The bracket is around 18 bucks. Or you can get some padding to shim. The loose gas tanks can easily be seen. Take off the under body panels. Push the tank from the bottom. You will see it right away. if you decide to replace the bracket, you should support the gas tank 1st. The bracket is to hold the tank in place;without it, the tank will drop.

crazypotato

Or you can take it to a mechanics, it won't take more than 15 mins. 6 screws off the panels reveals the tank. It is the 1st generation MB has decided to go with a plastic tank and moved it under the seat to save space. W210 has the tank in the trunk and it is tightly secured. Once you see the bracket, you will see what kind of bad design I am talking about. There is some plastic padding on the bracket which is around 3mm thick. They are soft. The bumping force on the road will make the tank press it down easily and put the force on the bracket. Remember, Force = mass x acceleration.

GT-ER

I took a look at it a few minutes ago ( both sides of the tank ) and I could barely budge it with my hands, although with the jack I could push it up about 1/8" of an inch with relative ease ( My tank is half full so maybe the weight is what's keeping it hard for me to move? ). I'm not entirely convinced that this is my problem since it the thumping sound is awfully loud for a tank that doesn't seem to be all that loose. I'll wait till it gets nearly empty and try again.

crazypotato

Mine was making noise when I tap my brake. You know. Holding the brake, release and brake. 1/8" is around 3mm. It is enough for the tank to bounce around. Remember the tank can move in horizontally too. You should also check to see if u can push the tank side ways and front and back. I really don't know what else can make a thump noise besides that if the struts are intact. Inner bushings?

crazypotato

I just thought of something else. Owners of the SL-Class have been reporting a baffle inside the tank went detached and banging inside the gas tank. So, I would keep an open ear to the gas tank areas while driving.

GT-ER

Mine also makes a small thump in the rear when I tap the brakes. Maybe it IS the gas tank but being more than half full makes it really had for me to move it...lol.

crazypotato

I finally had a look at it. the front padding on the strap is totally wore. I used a jack to push the tank up. I am able to push it up and leave an inch gap between the tank and the strap. Damn. What is going on.. sigh..

GT-ER

Mine does the same but I put some padding between the straps and the tank and the noise is still there. Also, No matter how slow I go over the speedbump it will clunk...yet if I go really fast over random road irregularities it doesn't...you'd think it would be backwards.

crazypotato

mine doesn't thump at speed bumps but manholes on the street and at street speed. Which side of yours making noise?

GT-ER

Both. I got in my trunk while my wife drove my car a went over speed bumps and both sides would clunk. I replaced both shock absorbers and the noise is still there.

crazypotato

did you check your swing bar links?

GT-ER

By swing bar you mean anti-sway bar? I used a pry bar and also my hands to check for any odd movement and it's very solid.

What is odd is that it will ONLY do it on speed bumps...lol. I honestly think it may just be the airsprings that are worn out or something ( and will stay that way because there is no way I'm selling out the dough just to fix this problem ).

crazypotato

the linking bar between the wheel carrier to the sway bar. airsprings. I don't have them in my car. Now, after i placed some plumbing gasket making padding on the strap to fill the loose gaps. The noise seems to be more solid instead of a thump. Oh well, my only concern was that the fuel tank was constantly rubbing and hitting the strap. Any fracture in the tank is really horrible. The new padding should reduce the risk in that. I have also placed news paper in the front of the tank where there is a gap there.

crazypotato

http://www.etoolcart.com/Steelman-Wi...-JSP97202.aspx

If you can find a shop equipped with that, the noise shouldn't be hard to pin point. It is much better than swapping random parts.

crazypotato

hey GT, I used a webcam with a clip to attach it near the front subframe mount and took some videos for it. The movement there is horrible. The repair shop lied to me. They didn't change it at all. You might not have the same problem as mine. However, you can do what i did and use a webcam and a laptop. if you want the videos I got, let me know.

GT-ER

For you just for being so creative. What do you say has a lot of movement? The tank?

Anyways, I got someone to get into the car with me and he said he is 100% sure it's the air springs. He's had two W211 with Airmatic and they both eventually got the "body in the trunk" thump and he replaced the rear airsprings and the noise was gone on both of them. He said it sounded just like mine.

claywillard

I believe I have had the same "Dead Man in Trunk". Only 30000 miles. Raised car today. Checked suspension and fuel tank straps. Dropped fuel tank. Appeared to be scuff/rubbing marks on floor panel above tank. Inserted a few strips of foam pipe installation on top of the highest raised areas of the tank and refastened the tank in place. After a quick run, it appears, no more "Dead Man in Trunk".

crazypotato

I assume you went to a shop to drop the tank and stuff b/c it is quite some work to drop the tank.

bantares

did this noise ever get eliminated. i have the same problem in my 2000 S500 which i have owned since new. it just started a year ago.

Benz-O-Rama

We're famous. Problem investigated and resolved.