Originally Posted by 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

Originally Posted by 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.