Clunking noise coming from the front that goes away when brakes are applied.

[Tommi]

Hello to everyone, first post so go easy on me please As the title says I've got a clunking noise coming from the front suspension at lower speeds up to around 50mph that goes away after pressing the brake pedal on my 2007 CLS W219 320CDI, at motorway speeds there's no noise. I've been to two garages so far to check what it is and they have found one worn ball joint at first and replaced it but the noise is still there, they both said that it might be shock absorbers but I've changed them today along with springs and top mounts and it's still the same, car passed the MOT not long ago without any issues, brakes checked and pads and discs don't appear to be loose, it's driving me nuts at the moment so please help me with any ideas of what it might be. Thanks in advance

 

[OneForTheRoad]

There's so many joints and bushes on this model , diagnosing a knock is difficult. I once owned a 2008 w219 and changed every arm ,every ball joint and top mounts and over small irregular bumps it still knocked . I bought 2 used front suspension legs Inc springs and fitted them ,still it knocked . So good luck with this . If it goes away when braking maybe try new front caliper fitting kit and new pins , along with genuine pads . ??

 

[350cls]

When I had a very similar issue to what you describe, although it didn't go away when braking. It turned out to be lower thrust arms. Once I replaced these. No noise no clunks. I found it was worse when I went into a pot hole or uneven surface of any depth or bump.

What's the mileage, and do you have much service history with the car. If you do have SH, have a look over it and see what's been replaced that might give you a better idea to what and what hasn't been replaced suspension wise.

Also maybe book it it with a independent to have a good look over the suspension.

One thing I have found with the w211 and w212, if any of the ball joints or mounts aren't in decent condition, they will knock and clunk like mad. And they seem to go through mounts and bushes, joints, at a fast rate.

 

[optimusprime]

L;at time i had a noise from the front , was when the brake pad material had come away from the steel backing plate ..they look ok on inspection.But you wont see it until the pads have been removed ..

 

[drone]

I'm making the assumption that the suspension set-up is similar to that on the similarly aged c class, if so here's what stopped mine doing similar btw you don't clarify that the noise goes away only whilst braking or if you brake and then the noise is gone, I assume it's the former.
I renewed all the front suspension joints and damping components on my car, which had done 200000 miles+ fitted new brembo discs and pads, mine has the sport suspension btw and the noise was still present, I then pulled the arb bushes out and the arb powder coating in way of the bush was worn away and there was some corrosion. I bought some undersized bushes (by accident as it happens) and froze them in my freezer overnight and drilled them out about the same size as the area where they sit on the arb. I also polished the arb in way of the bushes. I used a rotary rasp for the drilling operation which was a little smaller than the diameter of the arb and the bush needed some fettling to fit perfectly.
I have some gun oil with teflon and lightly lubed them and reassembled them and they don't make the noise anymore. If I ever do it again I'd swap the oil for some graphite security lock dry lubricant as this works wonders, bit like black coloured pixie dust.
My sons poo poo this and say that the act of ensuring all the fasteners were torqued up removed any play in the system. don't mind either way I feel better because of it anyhow.
I can't remember the arb diameter I know it is greater than the standard suspension set up. Incidentally the arb links have different sized fasteners on the sport model.

 

[Tommi]

I'm making the assumption that the suspension set-up is similar to that on the similarly aged c class, if so here's what stopped mine doing similar btw you don't clarify that the noise goes away only whilst braking or if you brake and then the noise is gone, I assume it's the former.
I renewed all the front suspension joints and damping components on my car, which had done 200000 miles+ fitted new brembo discs and pads, mine has the sport suspension btw and the noise was still present, I then pulled the arb bushes out and the arb powder coating in way of the bush was worn away and there was some corrosion. I bought some undersized bushes (by accident as it happens) and froze them in my freezer overnight and drilled them out about the same size as the area where they sit on the arb. I also polished the arb in way of the bushes. I used a rotary rasp for the drilling operation which was a little smaller than the diameter of the arb and the bush needed some fettling to fit perfectly.
I have some gun oil with teflon and lightly lubed them and reassembled them and they don't make the noise anymore. If I ever do it again I'd swap the oil for some graphite security lock dry lubricant as this works wonders, bit like black coloured pixie dust.
My sons poo poo this and say that the act of ensuring all the fasteners were torqued up removed any play in the system. don't mind either way I feel better because of it anyhow.
I can't remember the arb diameter I know it is greater than the standard suspension set up. Incidentally the arb links have different sized fasteners on the sport model.

The noise is gone only when my foot is on the brake pedal with a little pressure and as soon as the foot is off the pedal the noise comes back but like I've said only on uneven surface and up to around 50mph. I will have a closer look at the arb bushes next then thanks for that

 

[Tommi]

L;at time i had a noise from the front , was when the brake pad material had come away from the steel backing plate ..they look ok on inspection.But you wont see it until the pads have been removed ..

I've checked the brakes and changed the pads and accessories but the annoying embarrassing knock is still there

 

[Tommi]

When I had a very similar issue to what you describe, although it didn't go away when braking. It turned out to be lower thrust arms. Once I replaced these. No noise no clunks. I found it was worse when I went into a pot hole or uneven surface of any depth or bump.

What's the mileage, and do you have much service history with the car. If you do have SH, have a look over it and see what's been replaced that might give you a better idea to what and what hasn't been replaced suspension wise.

Also maybe book it it with a independent to have a good look over the suspension.

One thing I have found with the w211 and w212, if any of the ball joints or mounts aren't in decent condition, they will knock and clunk like mad. And they seem to go through mounts and bushes, joints, at a fast rate.

The car is on 140k atm service history wise there is a lot but far from being full tho there's a big gap before the previous owner he seemed to care for the car. All the suspension arm's are in good condition thrust arm's are not new but been changed before, I'm gonna follow drone's advice and check the arb bushes next fingers crossed

 

[Tommi]

There's so many joints and bushes on this model , diagnosing a knock is difficult. I once owned a 2008 w219 and changed every arm ,every ball joint and top mounts and over small irregular bumps it still knocked . I bought 2 used front suspension legs Inc springs and fitted them ,still it knocked . So good luck with this . If it goes away when braking maybe try new front caliper fitting kit and new pins , along with genuine pads . ??

I've done pads and accessories been changed as well not long ago, this is so annoying and embarrassing that it drives me mad at the moment

 

[JoolsB]

Hello, new here and new to MB, but I had a similar problem on a Range Rover and it was the ARB links, should be a relatively cheap and straightforward job if you haven’t already changed them and won’t have cost you a fortune if it doesn’t work

 

[OneForTheRoad]

Hello, new here and new to MB, but I had a similar problem on a Range Rover and it was the ARB links, should be a relatively cheap and straightforward job if you haven’t already changed them and won’t have cost you a fortune if it doesn’t work

Good shout , easiest way to diagnose these on a w219 is to disconnect them and go for a drive . Just don't go mad into corners .

If knock still remains , it's not them . Costs nothing this way.

 

[Tommi]

Update it was the arb links, thanks for those that sugested that, one was totaly gone, the rusty one was rounded off and that was giving the clunk and the other side started the rounding process already, now after replacing them and the control arm I'm left with a little knock but only when I hit a big pothole and I'm guessing it's the front control arms as one had a tiny bit of play, I've already ordered them. Funny enough the ball joint was tight as it should be and it dont look like that tho Thanks again for all advice