W211 front end knocks and bangs over bumps? Help please

[lieutenant gruber]

An independent MB mechanic confirmed I needed a couple of suspension joints so I replaced them but the knocking over bumps is still there. I've had the car up on axle stands twice now but I cannot find a worn joint.
It knocks from either sides over a bump in the road. Not a clatter but a Knock: just like a ball joint.

Apart from suspension joints, what could it be?



The car is a 2004 E270 with 199k on the clock.

 

[onefortheroad]

hub ball joints worn , anti roll bar link arm top bolt needs to be tighter than tight , suspension leg top mount bearings worn . the small ball joint on the hub mount leg is another. im exactly where you are with my 08 cls , ive recently changed every front arm , both hub ball joints , the cars quiet as a mouse on roads like the a19 , but go where its like cobbles and a bag of spanners sound returns .

 

[thebiglad]

Sounds like anti-roll bar links to me. Easy and cheap to fix if I'm right.

 

[Westheath]

Common for springs to snap on those as well as the upper and lower ball joints.

 

[lieutenant gruber]

All the suspension joints were checked by a MB trained mechanic last week, so i dont think it will be one of those. Ill check the roll bar bushes.
Any other suggestion guys?

 

[onefortheroad]

it may well be the arb bushes with that mileage . the arb link arms are about £25 each for a decent make. you may also consider the balljoint in the torque control arm rear , where the arb link joins , they can wear also .

 

[Flyinspanner]

Droplinks?

 

[lieutenant gruber]

Would worn drop links affect the steering geometry?

 

[onefortheroad]

if the steering wheel has moved its more likely to be 1 of the control arms.

 

[lieutenant gruber]

tack rods, track rod ends, NS front suspension arm and OS upper arm ball joint have all been replaced in the last 2 weeks so the tracking (and therefore steering wheel) won't be right. I still have a knock if either front wheel goes over a bump though.
I desperately need two new tyres though and I'll have to have these fitted before I can get round to whatever is knocking. I was planning on having the tracking done at the same time as the tyres....hence the question about drop links and geometry.

 

[thebiglad]

Would worn drop links affect the steering geometry?

No.

 

[Westheath]

Common for springs to snap on those as well as the upper and lower ball joints.

Steering rack bolts loose ........... ?

 

[lieutenant gruber]

Don't think the SR bolts are loose. Another thing to look at next weekend. Cheers.

 

[lieutenant gruber]

2 new Goodyear tyres and a Trackrite Tracking tool ordered, so I'm be having a good ratch about to find that clonk this weekend.

 

[solidamber]

2 new Goodyear tyres and a Trackrite Tracking tool ordered, so I'm be having a good ratch about to find that clonk this weekend.

old post I know but
did you ever find a cure? .. Mine is doing this.

 

[DSK]

Top Mounts. Usually you can easily see and test everything but the top mounts.

I did a suspension overhaul on my Volvo. had the same issue, just knocking over anything but smooth surfaces. Changed arms and links on the Volvo to no avail. Even the MOT right couldn't see anything even when i operated it. So, off came the struts, replaced the top mounts rubber and bearing and now its brand new. Silent, minor vibration and clonk free.

 

[alexanderfoti]

Top mounts and shock absorbers themselves are common culprits on these.

 

[V6Matty]

I’d have said slick absorbers as well, for some reason in the 270’s they seem to be quite common to go, I had two over my 6 years ownership, the knock is almost a ratting knock and quite different to worn bushes or joints.

 

[Dean Fletcher]

Mine made a knocking noise when turning full lock turned out to be the thrust arm. Now replaced all good.

 

[Xtractorfan]

Anti roll bar itself wears at the bushings, it needs to be replaced, also check wheel bearings are adjusted to spec. Brake pads can rattle in the calipers, and calipers have been known to come loose.