ez53436

Hey all,

Just wanted to do a quick write-up of my experience diagnosing a front end clunk, in the hope that it will help someone else.

For months, I had a clunk/knock coming from the front end when going over bumps, big or small, fast or slow. I could even feel it in the floorboard. I looked everywhere under the front end and even in the engine bay looking for parts that could be worn and making that clunk.

From everyone else's experience, it looked like sway bar end links were a probable cause. I replaced them with new OE ones (which have a slightly different design) and torqued to spec. No difference, but the old ones were a bit torn up at 100k miles.

I didn't want to just throw parts at it because I felt that people who do that usually end up spending hundreds and hundreds of dollars on parts and some people can't even trace the problem and just give up because of the price of all those parts. I figured if anyone is going to be able to trace the problem, it will be an MB dealership. I have never ever gotten service done at a dealership before but the price wasn't as outrageous as I thought it would be. They charged $170 for an hour of diagnosis, which is high, but not insane. I used to go to a really good Jaguar indy who charged like $140 per hour, so 30 bucks more didn't seem too outrageous for techs who look at these exact parts every day. Anyway, after TWO visits and over 2 hours of diagnosis, the techs couldn't figure out the problem. They were really trying, though, I watched as 3 or even 4 of them were rocking the car back and forth and looking underneath and listening. The shop foreman talked to me for a few minutes and explained that they can't tell what it is but they would replace the strut bearings or entire struts next. I took it with a grain of salt. Luckily the service advisor was pretty nice and only charged me the $170 for everything.

Because I also have a creak coming from the front left when turning when stopped, the symptoms seemed to line up closely with those of bad strut mounts/bearings. Since the MB foreman had the same thoughts, I decided to go in that direction. So I replaced those (NOT FUN AT ALL!) with new OE parts and new OE hardware (all torqued to spec). No difference, but the old ones had cracks on the top rubber bushing which were visible from under the hood.

After thinking about it as much as I could, I figured that the next parts to replace would be either the control arms or outer tie rods. But I wasn't looking forward to spending that much, so I looked into other possibilities in the meantime. Sway bar bushings looked fine, they are H&R 26mm bushings that came with the new sway bars about 2 or 3 years ago, but I figured I would replace them just to be sure since the cost is relatively low and it's so easy to replace them. I got them from ECS for like $60 shipped (their shipping costs are ridiculous). Took the old ones off and they looked completely fine, no rips or hardening or anything like that. I went for a test drive after replacing them with the new ones (torqued to spec of course) with the new parts and BINGO!!!!! I've driven it about 75 miles since the replacement, and I haven't heard that clunk even once - and I drove on some really bumpy roads today.

I'll comment on this thread if somehow it comes back, but I'm really happy so far. I've been battling this nonstop for months, so I hope this is the end. Enjoying driving again!

I hope this helps someone in the future since I stayed away from those bushings because everything I read seemed to only note that they squeak when they start going, not knock/clunk.

On the bright side, I spent a lot of time under the car so I upgraded my jack and jack stands to make things easier and to be extra safe! I can fully recommend the Harbor Freight low profile/long reach jack #60678 or #68050 (I'm pretty sure they're exactly the same) and ESCO #10498 jack stands WITH Burger Motorsports Mercedes jack pad adapters. The jack is super low and easily fits under the front of my car with H&R springs and a CF front lip. It reaches far enough to get to the center front jacking point without a problem, and it lifts the car really, really high. Actually I think the Arcan XL2T jack is exactly the same design but around $100 more. I feel EXTREMELY confident under my car with the new jack stands and adapters, and I highly recommend them, even though they're pretty pricey. Also bough a creeper from Harbor Freight, which I do not recommend. The ball bearings are open and terrible and moving around is extremely difficult.

If anyone has any questions about how to do anything I've listed above, just let me know and I'd be happy to answer them. MBWorld has really helped me a lot and I feel like I have experience now to the point where I can feel confident helping others with similar issues.

Morphh

Nice write up, I have a squeaking noise in the passenger rear going over bumps, i can push down on the car rear passenger side and hear it squeaks, I have 03 c32 with 84,000 kilometres, I will check the sway bar bushings?

Supgee

I'm glad you got it resolved, but I would be weary of that dealership. A front end clunk is usually from a worn sway bar link or bushing... What kind of dealership could not diagnose this? At the dealership I work at, no fault found diagnoses only end up with a $69.99 charge regardless if we spent an hour, or even 1.5 on it. We have some techs who are paid hourly and not flat rate, so it's no biggie for them to waste a bit of time and charge you for the no fault found.

ez53436

I agree that I'm not happy about the fact that they couldn't find the issue but in their defense, the bushings that were causing the noise looked NEW. They really showed almost no wear at all, even after taking them off. In fact, they were only about two or three years old.

Either way, I'm glad I fixed it. Now I've gotta trace slight steering play that has plagued this car since I got it. Outer tie rod ball joints look fine. I'm thinking the issue lies in the inner tie rods or steering rack.

frejo

Bumping this thread since I have run into some trouble. When I tried to unscrew the nuts to change the bushings on the sway bar one of them snapped and the head of the other got ruined. Any ideas on what to do?

What is the size of the inverted torx bolt?

tw2

Thank you for this writeup. This is what i am experiencing currently. Swaybar bushes were top of the list.

If no one reports i will check the socket size tonight when i investigate my clunking issue under the car.

tw2

12mm

Khan 55

hello....where on earth is the jacking point on the front as you mentioned? I battled to do a oil service on tranny and engine as I hadta use my 3ton scissor jack under the normal jacking points where I placed bricks under the front wheels to keep the car up so I could crawl under. I checked those stands out with the interchangeable mounts for Merc posted on another thread somewhere. I suppose I would have to freight these one day over to my side as all my life I preferred working under a car with jack stands and nothing else. The Merc is no light weight contender at all and even with std suspension, if it came down on you whilst under there, you gona be flattened for sure.


Congrats on diagnosing the issue. Wonder if my car makes that clunk like noise. You say its more audible over humps and on bumpy roads?


Loose steering or excess play on the steering is usually contributed to rack ends not necessarily tie rods. I know on Toyotas one would apply pressure with your index finger of your right hand on the straight or horizontal part of the steering downward and let go or rock it by pushing down n letting it come up by itself and then pushing down again but doing this repeatedly to inspect worn rack ends. There is a minimum allowed travel. I suppose we would do this whilst the engine is idling to engage the power steering rack else it would be a fail?
Try it out and check what your observations are. You could alternatively just pop the tie rod end out with the correct tool and see if the rack end with tie rod hangs or holds in any position you move it to. Obviously if its worn it will then just hang regardless.

Khan 55

For suspension components, the best tool to use when braking tight bolts is a long power bar. Prevents frustration and hassle as well as possible injury when loosening bolts or nuts. I have the normal size one which I think is 20inches long and one double that length if not 50 inches long which I use on cv joint castle nuts.

MarcusF

SNIP


Bricks are dangerous. I mean really dangerous. I never use them. Ever. They'll patiently wait until you get under the car, then shatter without a moment’s notice and drop the car on you. I use wood. Soft wood can crack, but you can see it and even if it cracks it won’t completely collapse like a brick. Hardwood is better (typically doesn't split) but either is superior to bricks. $25 worth of 2X4’s and 2x8’s from a home improvement store is all I needed to build 10 inch stands for all 4 corners. OK, well, $25 in wood plus my table saw and box of screws. Seriously, you might want to consider not using bricks. If you live near me (and you supply the wood) I'll build you stands for free. It takes about 30 minutes to cut the wood and screw the stands together. You can also put a jack pad on the wood stands and use them under the factory jack points. I do it all the time on a W204.

Khan 55

Marcus. I actually found your thread when I googled it. Thanks for clearing up some questions I had. I would have come by but it would cost me quite a pretty penny to obtain Visa, fly across the sea from South Africa and then get a taxi from the airport to visit lol. I will consider this when I need to make exactly what you did.


Stupid question but what do you do when you need the front wheels off?

TruTaing

This is very useful. I have a very similar clunk right now and I have the H&R front sway bar! Def will look into it!

MarcusF

The W208 has a center jack point. I haven't checked the W204, but it probably does as well. At any rate, using a floor jack I lift it by either the center jack point or front A-arm, slide the wood stand under the factory side jack point, set a 4 inch long, 2 inch wide, 2 inch tall piece of wood on top of the wood stand directly under the factory jack point (to ensure I'm only resting the car on that factory jack point), and then set it down. For the rear I use the diff to lift both sides and set it on the wood stands.

tw2

Yes W209 has the centre point, not sure about W203 but I assume they all do. There is a rubber mount in the middle of the main plastic undercover. I always take the cover off to access it as my jack is not that great. I lift it from the centre point like Marcus and then put steel jack stands at the normal side jack points and leave all 3 holding the car up.

ez53436

As far as the front center jacking point, if you look under the front of the car, about two feet from the front of the bumper. It looks like a dark, rectangular, hard plastic piece that's attached to the front subframe. You will see a cutout in the front belly pan for it.

As for using bricks, I would highly advise anyone not to ever do that. What I would definitely recommend for our cars is a good set of jack stands like the ESCO 10498s along with some metal adapters to fit into the factory jacking points, like the Burger Motorsports Mercedes/BMW jack pad adapters. If you need something to hold the car up by the wheels, I would advise making something out of wood. I made ramps out of 2x10s from home depot that work perfectly. A good jack that I would recommend is the Harbor Freight 2 ton, low profile, long reach jack. The 3 ton is not as low or long, so it won't reach the front center jacking point.

In any case, be safe while under the car guys. It's cheap life insurance!

kent426

You may also want to look at the shock tower bearings, i had two set go bad already, they start creeking when you are at a stop and turn the wheel

MarkBrickey

EZ, this steering play... does it give vibration at about 60-70mph? I've been fighting this for 2 years and keep being told wheels are out of round, even when I just had wheels trued/rounded @ $85 each!

Morphh

Tommy Ellington

Jack the MB up bouth wheels hanging loose, check the swaybar rubber bushings. If the sway bar moves inside the bushing freely unmount and use rubber band twelve times around the swaybar and place the rubber busching over it in place. Install in reverse order. That works fine for me. No more clunk!

Tommy Ellington

Jack the MB up bouth wheels hanging loose, check the swaybar rubber bushings. If the sway bar moves inside the bushing freely, unmount bushings holders busching rubber and use rubber band twelve times around the swaybar where bushings is mounted.replace...

tw2

Or replace and lube bush?

Tommy Ellington

My swaybar was teared 3-4 mm in diam. Got 260000 km new swaybar cost 120 euros

buito

I replaced the sway bar links (the rubber around the top bolts was teared) and the noise continues. I removed the sway bar links and drove the car and the noise continues. It makes the noise when starting from a traffic light and when going over bumps as you turn. Checked the front suspension and do not see any unusual wear on the parts except movement in the coupler in the steering shaft.

Any ideas?

Ossaidamg

Helder Soares

Hello
Can you help me what/how much torque Nm you used to tight the screws?

Torque specs for sway bar bushings and sway bar link?

Many thanks and congratulations for the post.