markaspirenet

I have a UK CLK 280 - 2007 - Low miles under 40,000

Not sure if this is the right place to post? I think it will be a W209 (no 280's mentioned).

I have a clunk in the boot, this happens when I go over a speed bump, it sounds like there is something in boot bouncing around like a loose jack but it's totally empty, everything is tied down securely

I garage looked at it and said all was well and pointed out it could be a number of bushes, about 6 different ones, naturally I don't want to replace everything.

I heard that this 'body in the trunk' is common on some Merc's. Wondering if anybody has anything to input

Thanks

Mark

Yidney

You are in the right place. It's always hard to diagnose noises without being there in person. I don't think CLKs are known for making a random noise from the rear that cannot be diagnosed. Have you tried totally removing your spare tire and everything under there to see if that changes anything? That would be the first thing to try. At your low miles, the next thing i would suspect is the exhaust system bouncing, or maybe a body under panel. After that maybe a shock mount. I would think your mechanic could do better than just to tell you there are a bunch of bushings under there.

markaspirenet

yeah, agreed,I need to get somebody else to look at it.

Good point on removing everything, I was thinking the same thing myself just keep forgetting to do it.

I'm going to take it for a drive on a bumpy car park while I have the back seats down to see if I can pin point anything while the wife drives, but I suspect it just sounds like it's in the boot and it's a bush or suspension issue

Yidney

A busing usually will not make a loud sound until it is also visibly failing. They are basically rubber donuts with an inner steel mounting sleeve and an outer steel ring that is part of the suspension arm itself. The inner steel sleeve is held tight by the mounting bolt - or should be. So until the donut fails, there is not much that can make noise. What I just said applies to the bushings on your suspension "arms" - of which there are five on each side - so basically 20 bushings total (2 are actually small ball joints). But a visual inspection of those bushing should be able to eliminate them, and they typically would not fail by 40k miles. In addition to those 20 points of movement, you have sway bar. The sway bar connects one side of the suspension to the other. It is connected by two rubber bushings, and then has a "end link" on each end. The end links are short "L-shaped" arms, each with a rubber bushing on each end. So that is 6 more points of movement, and 6 more bushings to add to the total. The two main sway bar bushings are more likely culprits for your noise, especially if a bracket has come loose. The end links are more likely to squeak than clunk. Then each shock has rubber bushings at the bottom and top. So that's 4 more potential places for noise. So we are up to 30 now. Then your suspension itself bolts to a large carrier, that itself attaches to the chassis with rubber bushings - I think 4. Now, 34 bushings of one type or another sounds daunting, but they are not hard to look at and inspect.

markaspirenet

Oh wow, time for a new car! There are 20+ speed bumps getting out of my town (each direction), drives me mad. Once I'm out it's fine, no noise.

It is a little bumpy at motorway speeds, I'd say a little bit beyond firm, you feel everything, but I've heard Avantegards can be like that. I put new continental contisport 5's on it (wanted Dunlop sport max but the tyre shop screwed up and I had to have something on that day) but they didn't help, in-fact I am sure they now cause a sound I have when I break, lots of road noise when on the breaks at higher speed, take my foot off the brake, quiet, back on, noise, again nobody can find the fault, maybe the tyres are bad, don't remember having it before hand.

Nothing more annoying than faults that can't be found.

sailorben

40,000 miles isn't that many, yet the rubber is still 10 years old.

I'd check exhaust mounts, drop links, and anti-roll bar bushings, initially.

When I have noises, I use a local garage whom I'm friendly with, they have a plate on their ramps which will shake the whole car, revealing any weaknesses.

Is there vibrating in the pedal; associated with the breaking?

markaspirenet

I've never heard of a shake plate, very interesting, although mine seems to be when the car bounces up and down only on bumps in particular speed bumps

The breaking - No vibration, I've had new brakes on it. It's kind of a whiring noise, best described like a lot of road noise like I have changed road surface, but the second I take off the brake pedal it goes. I suspect the it's the new tyres even though the tire shop says they are fine, the quicker I wear them out the better.

sailorben

The problem with suspension knocks that are hard to replicate, are that they are often hard to see, the rubber might look good, but only in specific circumstances is the force transferred in the right direction to create a knock on metal.
Whereabouts are you in the UK?

markaspirenet

Yeah I hear you, I just hate to go on the path of guessing and replacing parts, I'm going to guess it's not a cheap job to start pulling all of these parts off and hoping it's going to fix the problem.

Btw: I did have the most bizarre grinding sound when I turned my wheel, this was last year, the garage put the brakes on, only to find it was not the brakes, it was a plastic clip that had broken holding the handbrake cable, and the cable was catching on the drive shaft only when I turned the lock one way (I know-odd). I can't be sure but I think it might actually started knocking after that, so I am wondering if they didn't put things back where they belonged. They have looked at it but didn't find anything, I need another set of eyes on it.

FYI I am located in Glossop, close to the bottom of the A57 snake pass, the best road in the world! ;-)

mrbobby

Is the noise a clunking or is it a mechanical type clinking? My W 290 had a metallic clinking sound that only occurred on a speed bump type situation. After checking all the bushings and mounting points we found a broken rear spring. The break was almost impossible to see. Only the last 5" or so of the spring was broken but still held in Place. I'm not saying this is what you have but it is something I would check. Check very carefully because the break is very difficult to spot. Good luck with the repair.

markaspirenet

no it's not like that, it sounds like I just have a medium weight box in the back that is moving around, or the dead body that others have talked about in another thread that I found, but I've checked for a body, nothing.

gaazmon

Mark, I am experiencing the same issue. Literally like you said a 'body in the trunk' type noise. My indy has not figured anything out as well and other people notice it as well when going over the speed bumps.

I'm betting on the sway bar bushings, but my indy stated they look fine. The sway bar bushings on these updated models is funky with the bushings and I feel like the only real cure is to replace the whole bar since the bushings are attached (from what I remember reading on the forum versus the older design with removable bushings).

Interesting, I'm having the same exact issue when I turn my wheel all the way one way and wondering if this could be the reason.

And I actually getting a slight grinding noise when coming to a stop even though my brakes are okay, but could be time to change the rotors with the next pads change.

sailorben

Grinding could just be the whole handbrake shoe mechanism just being out of position. I had that issue on my first clk.

gaazmon

Thank you. I'll have that checked out next time as well.

markaspirenet

I fixed the knocking noise in the back, no garage required, fixed it myself!

I have to say it started with me dropping the rear seats and having my wife drive over a car park that was cobbled, so I could go in the back to try pin it down, wow did that make me feel sick!

Here's what I did, I found that by pushing down on the boot lid that it had a bit of a squeak, I put some WD40 on a cloth and rubbed it into the boot seal, but then while pushing to test the squeak I noticed the boot was solid on one side, and I was able to move it a little on the right side, I could push it down a little. I adjusted the boot with the little twist out thingy on the boot, just enough to stop the movement, and not too much that shutting the boot required a slam, took it for a test drive over the same speed bumps.. fixed!!! I've driven it for some time now, over countless speed bumps, it's perfect.

No suspension parts required, no big bills. This car had been to a third party merc garage, and also to the main dealer, neither of them found it!

Oh the American's out there please replace boot with trunk ;-)

gaazmon

Wow. Such simple yet likely solution. I have adjusted mine as when I was pushing down on my trunk on the sides there were creaks and slight bouncing (more so on the passenger side than the drivers). I've adjusted the knobs and made sure the self closing wasn't pushing too hard when latching down. I will test out and see if the sounds have disappeared as well.

markaspirenet

I see you're in the USA, mine was in the drivers side, in other words the right side, it appears yours is also on the right side being a left hand drive making that your passenger side, so same side as mine.

I don't think the lubrication that I put on the seals were part of the fix, but no harm done by softening up the seal before adjusting the truck to make it nice and snug.

Hopefully it'll also be the fix for yours, I've put plenty of miles on it now, and I have around 26 speed bumps in each direction to get out of my time (yes the road planning council are a bunch of a##holes), and it's not done it once, before it did it every single time, did sound like a suspension problem, and yet, like you said such a simple fix, it really is shocking that the main dealer never spotted it.

markaspirenet

It's been two months, countless speed bumps and I can confirm that this fixed the problem, not a single knock since.