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Discussion Starter #1 (Edited)
2002 CLK55 Convertible with 39k miles.

A few months ago I noticed a moderate "clunk" when turning right and up into my driveway. the sound would come and go. Recently had a free MB Tech Session at the local Benz dealership where they go over several points with you. Technician diagnosed a leaking drivers side motor mount and lower control arm bushings that had a very, very slight amount of play. He said those bushings didnt need replacement now, but maybe next year or 15k miles left on them. (roughly). He checked the ball joints and there was no up/down play in either wheel. He checked tie rod joints, etc. All seemed fine.

Using instructions on this forum, I successfully replaced the leaking drivers side motor mount. This did not fix the "clunking" from the front end. Neither did replacing the steering damper.

Last couple of days the temps have risen to high 80's. Went for a drive into the city (Georgetown section of DC) in a lot of traffic the other day, and the clunking/popiing was definitely more pronounced in the heat. Slow turning into a parking space? A pop or clunk would happen. Slowly taking off from a light while turning the wheel? Pop/Clunk. Slowly taking off from a light with the steering wheel straight? Pop/clunk. Earlier today..driving through the shoppinh center parking lot. Passenger side went up over a speed bump while the drivers side stayed flat on the pavement...pop/clunk.

Today I jacked the front end of the car up and turned the steering wheel from side to side. No noise at all. No play in steering wheel. Steering seems nice and tight. The steering box bolts are also torqued to spec.

Based on this info...what could it be?

I can also feel the clunk right under my feet as Im driving.
 

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Check your sway bar end links and bushings. The pattern you have mentioned seems to be when the sway bar is working it's hardest (one wheel on the ground, another in motion up/down like when over speed bumps and entry into driveways). Cost wise about $350 at the stealer parts and labour with new sway bar.
 

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2002 CLK55 with 39k miles.

A few months ago I noticed a moderate "clunk" when turning right and up into my driveway. the sound would come and go. Recently had a free MB Tech Session at the local Benz dealership where they go over several points with you. Technician diagnosed a leaking drivers side motor mount and lower control arm bushings that had a very, very slight amount of play. He said those bushings didnt need replacement now, but maybe next year or 15k miles left on them. (roughly). He checked the ball joints and there was no up/down play in either wheel. He checked tie rod joints, etc. All seemed fine.

Using instructions on this forum, I successfully replaced the leaking drivers side motor mount. This did not fix the "clunking" from the front end. Neither did replacing the steering damper.

Last couple of days the temps have risen to high 80's. Went for a drive into the city (Georgetown section of DC) in a lot of traffic the other day, and the clunking/popiing was definitely more pronounced in the heat. Slow turning into a parking space? A pop or clunk would happen. Slowly taking off from a light while turning the wheel? Pop/Clunk. Slowly taking off from a light with the steering wheel straight? Pop/clunk. Earlier today..driving through the shoppinh center parking lot. Passenger side went up over a speed bump while the drivers side stayed flat on the pavement...pop/clunk.

Today I jacked the front end of the car up and turned the steering wheel from side to side. No noise at all. No play in steering wheel. Steering seems nice and tight. The steering box bolts are also torqued to spec.

Based on this info...what could it be?

I can also feel the clunk right under my feet as Im driving.
Dead or loose shock maybe? Check the mounting bushings also when your at it
 

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Discussion Starter #4 (Edited)
thanks guys. Just left the parts counter at the Benz dealership in Maryland. two different parts guys were checking the computer. they said the 2002 CLK55 AMG Convertible has no endlinks/swaybar links up front. Is that accurate??
 

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I had a worn out steering damper/stabilizer that clunked when wheels turned past a certain degree, have you checked that out? At 100k I am slowly beginning to change out worn out parts, fun times!

Apologies for my 2cents, skimmed posting, overlooked "Neither did replacing the steering damper."
 

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thanks guys. Just left the parts counter at the Benz dealership in Maryland. two different parts guys were checking the computer. they said the 2002 CLK55 AMG Convertible has no endlinks/swaybar links up front. Is that accurate??
Correct.. u have no endlinks. It mounts dirctly to the LCA with a bushing.
 

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Discussion Starter #7
replaced the front swaybar bushings with OEM from dealership. 4 bushings replaced and properly torqued down with fresh coating of blue loctite on bolts.

No improvement whatsoever. (but it was worth a relatively cheap try..$55 or so total for all 4 bushings).

It's gotta be lower control arm bushings. The dealership (in that initial inspection) noted that the caster bushings had slight cracks in them, and that there was a "small" bit of play in the bushings. The independent who checked after the dealership said the play was too small to warrant replacement, in their opinion. Said I had at least another year/15k or so miles on them..maybe more.

The knocking/clunking is imperceptible above say..30mph. 15mph and below when going over a speed bump, turning into or out of a driveway, or even turning from one street to another slowly while slightly accelerating can cause the noise. (like while waiting to turn left on yellow into a small street.). It's even occurred while accelerating slowly from a complete stop when changing lanes. Steering itself feels fine. Smooth, with no deadspots, etc.

The clunk is real annoying. I think my next step is to take it into a very reputable Benz independent specialist and give them the car, the symptoms, and have them figure it out. I definitely dont want to blindly continue throwing money at this to chase it down.
 

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The sound you're describing is very much like the sound the REAR sway bar links make when they are bad, other than you say the sound is coming from the front. Are you sure the sound is coming from the front?

One of the things I was able to do when I had the problem was drive the car in a circle and have some one stand in the middle of the circle so they could try to determine where the sound is coming from. If it's in the back, odds are that it's the sway bar links. Which, btw, are the least expensive part you'll ever buy for this car.

But, besides that, it's sounds like you may have a broken shock. Have you had your shocks checked? When were they replaced last? If you have more than 50-60k miles on your shocks, they are nearly dead and you should replace them anyway. These cars are heavy and the shocks need to be replaced more regularly than other lighter cars.

btw, I had multiple alignment shops trying to figure out the rear sway bar link problem I had and none of them could figure it out. It was a factory trained mechanic that pin pointed it for me. It took him less than 15-seconds to identify the problem.
 

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Discussion Starter #9
Thanks. Yes, it's definitely from the front. Ive listened carefully with top up and with top down and also I can even slightly feel it in the floorboard under my feet when the "clunk" or "pop" occurs. When I replaced the front swaybar bushings this weekend I gave everything under that front end a solid visual inspection. Springs arent cracked, shocks arent leaking, and the handling is still top notch. (only 39k miles on the car)

Im really thinking that the LCABs are the culprit. The factory tech visually spotted the cracks in them, but when he pried against them with a long prybar, there wasnt (in his opinion) enough play to warrant immediate replacement. A second opinion at a local German independent said the same thing. However, perhaps those cracks are enough to be the source of the popping/clunking at low parking lot type speeds.
 

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Discussion Starter #10 (Edited)
So I take her in to a highly recommended Benz independent here in Maryland. He puts her on his lift to inspect takes her out for a test drive. Says there is absolutely nothing mechanically wrong anywhere at all with the car. Says the LCAB's are fine and certainly dont need replacing now. He double checked everything that was already checked, and confirmed entire suspension/steering/etc is perfectly fine.

he says what Im hearing is a combination of: Convertible chassis flex/creak combined with AMG sport tuned suspension combined with aftermarket 19 inch wheels with 35 series tires up front and 30 series out back. Says 19's were never designed for this suspension and their weight combined with their size can potentially enhance any existing suspension/chassis noise especially on a AMG Vert.

So..case closed. I may end up going down to 18's when these tires wear out. Before then, Im still going to examine the torque on the chassis cross braces present on the verts. Just as a check.
 

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Discussion Starter #11
Update: Im convinced..this is not due to wheels, or at least not solely due to wheels. It makes no sense that wheels would be the culprit when Im (as an example) at a stoplight in downtown DC in 90 degree temps. Top down (as I always do) I gently pull away and within 2-3 seconds I hear/slightly feel a "thunk" just under the drivers side footwell area.I've also felt it in the passenger side footwell area when riding as a passenger. In cooler temps the thunk is either not there, or is very, very muted. Hot weather after the car has gotten fully warm after several miles of driving, especially in stop and go? It's noticeable. My thought is that the lower control arm bushings are the culprit, even though they "arent that bad" per the independents and have minimal play in them.
Im thinking that in a Convertible chassis combined with the stiff AMG suspension and the large wheels, failing LCAB's noise is more prominent than in say, a 320 CLK coupe.

Thoughts anyone?
 

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I have a 2000 convertible with a clunk that eventually became a rattle on brick roads. It was the control arm(s) bushings. They were visually worn and shot. Replaced them and no more noise.
 

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Something to check as mentioned earlier is your shocks. I just finished installing my new shocks and had only snugged up the lower mounting bolts until I got my hands on a torque wrench and man what a nightmare in the noise department! Even going through drive through for coffee the shocks would make a clunking noise. High speed wasn't as bad as low speed (I think because the city streets are worse than the highways) I honestly thought it I had a bad muffler mount that became more apparent due to the sport suspension. Now that they are torqued the car is quiet again.

I will add, even though the bolts were slightly looser than spec there was no way I could move the shock and seems as though it would only be discernible by physically checking the torque with a torque wrench.

Whilst changing the front shocks I did see that there are no sway bar end links up front, only end bushings, the rears however are end links and made out of plastic, hmmm.
 

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the most common way people find out their lower control arm bushings are bad is due to a clunk whenever they are say backing out of a parking space and then hit the brakes to stop. i would try letting the car sit, then back up in reverse for a few yards and hit the brakes to stop the car. if you get or feel a clunk then the lower control arm bushings will be your problem.
 

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I really think that the noise that you are hearing are the tires skipping. Both of my last 2 208s had this issue at low speed (parking, inside a parking garage, turning wheel while going out of driveway). I have always had PS2s and find it more noticeable when they are cold. I just accept it. I have no uneven wear and have 93K miles on my 55 right now. When I first heard the noise it drove me crazy thring to figure out what was wrong. I had someone drive as I got real close to the wheel while turning and you can actually see the tire hop slightly as it tries to stick to the pavement but you are forcing it to make the turn.
After re-reading, I have not experienced it going straight over a speed bump.
 

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Discussion Starter #17
FINALLY SUCCESS!!

So I took the car into another local Benz Dealership here in Silver Spring, MD. Gave them a detailed letter explaining how/when the symptoms occurred, what work was recently done to no avail, what the independents said, etc. Told them to keep the car as long as needed to resolve.

The tech drove the car and heard the noise and felt it under his foot as well..just like I did. Put it up on the lift and found nothing wrong at all with steering/suspension. Said all was in spec and in perfect condition. He said the same noise was/is a common complaint of SL owners. Said the fix is to hit the bolts that hold the under chassis convertible cross braces with the impact gun and snug them down VERY tight. He did that, drove it, and no longer heard the noise. I took the car on a 140 mile round trip yesterday in high heat temps with a combination of traffic, varying elevations, high speed runs, low speed runs and low speed turns/stops. Complete silence. Not a thunk, clunk, or knock to be heard.

Dealership charged me 1/2 hour of labor.

My confidence in dealerships is renewed. lol.

Hope this thread may help other W208 convertible owners who may have this same issue.

P.S. I actually did check the tightness of these same bolts myself a few weeks ago, but I only used a hand wrench. The bolts were definitely tight, but obviously not tight enough.
 

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FINALLY SUCCESS!!

Said the fix is to hit the bolts that hold the under chassis convertible cross braces with the impact gun and snug them down VERY tight. He did that, drove it, and no longer heard the noise... Complete silence. Not a thunk, clunk, or knock to be heard.

P.S. I actually did check the tightness of these same bolts myself a few weeks ago, but I only used a hand wrench. The bolts were definitely tight, but obviously not tight enough.
Glad to hear you solved the problem! I am sort of kind of shocked by how much noise can come from such minute movement and by how deceiving bolt torque/tightness can be. As I mentioned earlier I had my bolts fairly snug and could not move the shocks even with my pry bar but it still made a wicked clunk noise over bumps. That should be one headache your glad to be rid of! :)
 

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Discussion Starter #19
Glad to hear you solved the problem! I am sort of kind of shocked by how much noise can come from such minute movement and by how deceiving bolt torque/tightness can be. As I mentioned earlier I had my bolts fairly snug and could not move the shocks even with my pry bar but it still made a wicked clunk noise over bumps. That should be one headache your glad to be rid of! :)
Thanks! And yes, REALLY glad to have this finally fixed. Yes, I too was somewhat suprised at the level of "clunk" that this made. Ive owned and wrenched on cars for over 20 years now. I've had LCAB's go bad (BMW) and know what that sound/feel is like. I've even had a crack in a subframe near a control arm (1981 VW Jetta) years ago that made a similar noise, so imagine my suprise when it turned out to be these cross brace bolts. What threw me was the temp related changes. In cooler weather (say under 80f), there was no clunk. Driving in 90+F temps..and in downtown traffic? The clunk became much worse. And chassis flex (ie one side of the car on level ground the other going over a speed bump) was the real test.

Anyways..glad it's been resolved. Other than that clunk, the car (driven only on weekends) is literally flawless in every way. (41k miles now).
 

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Unbelievable! I'm glad you got your issue resolved...I'm also bummed because I have the same exact issue with my 02 55...and I mean exactly the way you described but I have a coupe! I have read through threads periodically for a resolution to no avail. Just when I thought I was getting somewhere...a convertible specific part. I too have wretched on cars for years and this has left me scratching my head. Thanks for the updates and finally the answer though...so frustrating when people ask for help, figure out their problem and ditch the thread leaving us hanging. I guess I will stay as persistent as you have and hopefully find an answer.
 
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