I am trying to identify a rattle that comes from the rear of an 83 300D. The car has 171K miles and recently moved from a southern climate to Minnesota. The "rattle" is pronounced when going over bumps and making turns, more so to the right than to the left.

It sounds as though something is loose or maybe the muffler is hitting something under the car. I've crawled under and the muffler looks good, no missing donuts and it has the right amount of play. I checked the sway bar and that seems OK too. I don't see any loose components such as shocks or springs which would be making this noise. When a rock the car when parked, I can't get it to make the sound it makes when on the highway. Any ideas or recommendations would be appreciated. Thanks!

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99 E300 133K
98 ML320 99K
87 Saab 900 Turbo Conv 123K

Usually it is the sway bar link that fails. We sell them for a whopping $7.00 each. You need two.
You can find it in the fast lane under suspension.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Check the linkages that connect your sway bar to the control arm. My 300D is making the exact same noise, and that is what I realized is making the noise.

Greg

I have this same problem, but can't find any loose linkages while rear end is jacked up. Should I check the linkages when full weight is on the rear suspension instead?

Also, what about the linkages fails? The bushing connector that connects it to the control arm?

I also may be checking the wrong part. The piece i'm looking at is plastic, and connects to a very small bar that runs across the car to the other side. Is this the sway bar? The linkage runs parallel to the rear shock.

Thanks for any help!

~Paul


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'91 300E 199k

Paul,
Yes, that's the right part. The little linkage arm has a bushing in each end that eventually wears out; the play in the worn bushing makes the clunking noise.

Theoretically, it shouldn't matter if the car is jacked up or not, as long as it is jacked up on both sides or neither side. The sway bar functions by twisting as one side of the car becomes higher or lower than the other side; the more the car tilts, the more the sway bar resists further tilt. If the car is tilted - that is, you jacked up one side but not the other - then the bar is twisted and there is pressure on the sway bar linkage arms, so you can't tell if the bushings are worn or not.

The easiest way to tell is with the car sitting on a level surface: get down near the rear tire, locate the sway bar arm and try to wiggle or move it. If it's worn, you'll be able to wiggle it and it will make the same noise that you occasionally hear from inside the car. It's very easy and inexpensive to replace, but you have to jack up the rear end of the car (both sides at once) and remove the wheels. Then, the linkages come out with one bolt on each end.

- Nathan
'83 240D "Steiner"
'00 New Beetle TDI

P.S. a mechanic that I *USED* to use tried to tell me that the noise I heard was actually my rear differential failing. bah.

Paul:

My old 220D (very similar rear suspension) had both links completely missing. Handled very strangely until I found they were gone.

Check the two bushings that hold the sway bar to the bottom of the trunk, too. These can get old and hard, and allow the sway bar to thump around. Sounds like a full glass soda bottle fell over in the trunk, or something is rolling around.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Fairly common problem for your car. Plastic sway bar links connect the metal sway bar to the front of the hub assemblies. They have two ball & socket assemblies that wear out and make a heck of a racket.

I was unable to learn anything about their condition by shaking the plastic links themselves. But ordered them on general principle since they looked really old. However, with the wheel off, I had the leverage to push the sway bar itself up and down and reproduced the noise exactly. Upon replacement, the sway bar clunks were gone. So quiet I can hear the rest of the suspension "complaint" noises.

This is a fairly easy DIY job. Take off the wheel to get good access to the links - they unbolt rather simply.

Ken
'82 300D

In my 1990 300te 4-matic, I also experience the same type of problem. Only mine is more pronounced at slower speeds, and somewhat bumpy roads. Could I have the same problem, or would it be something different on my car?
Thanks in advance,
Chris

I truly appreciate all the responses, thank you all for your help.

HOWEVER

I replaced both sway bar links and the rattle over bumps remains. I inspected the bushings on the old ones and while they were a bit brittle, they were still intact and preventing metal to plastic contact. I had a feeling at that point that this wouldn't resolve the problem.

Anyone have an idea what I should check next?

I CANNOT find any loose or totally worn bushings on either side of the suspension, that might be causing the problem. The muffler donuts are OK.

Benzmac, are you out there? Plan B??

Thanks again,

Paul

Try your emergency break. If the break is loose you may have some rubbing that will produce the metalic clanking sound. Just a thought because I heard the same thing on my Mom's 300D Turbo Diesel while taking it to the shop.

Brian

I had some rattles, etc. and found several loose bolts on the transmission mounting brackets. You might want to check them out. Easy to do with car jacked on one side. USE JACKSTANDS!!!

The only other possiblities with this rear end are:

Loose junk in the trunk

Loose upper shock mount (since I assume you checked the lower one)

Split sway bar mount bushing that looks fine but allows the swaybar to thump

Loose or split differential mount, top (four bolts) or rear

bad or missing control arm bushing -- this usually makess the car "throttle steer" excessively, too -- pulls one way under trailing throttle, the other under acceleration (another thing wrong with the 220D). Very rare, but possible.

A broken parking brake shoe could do this -- I assume you don't have a wheel cover, so it couldn't be something loose in there, either.

And check for loose brake calipers or pads -- I'd be suprised if this were the case, but check anyway. If the anti-rattle spring is broken, it is possible for the pads to get loose.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Well apparently it is the parking brake cable that needs adjusting that's causing the rattle as Brian mentioned, and Peter confirmed.
Thanks guys

I got underneath the car and shook the cables that run just underneath the axle drive. It produced the exact sound I've been hearing at BOTH wheels, so apparently I need to tighten/adjust the parking brake.

Read some posts on how to adjust from down there and the only 10 or 11mm (forget size) bolt I saw I tried to tighten, and it would NOT budge. I sure hope that doesn't mean the cable is stretched to its limit. In its current state, the parking brake almost is to floorboard before it locks.

I guess I'll take it to a local shop and have them adjust it (can't be more than .5 hours to adjust can it?) or try again myself at each rear wheel tommorrow.

Thanks again for the responses

~~Paul