W211 knocking strut top suspected - is this the right part?

[MJJ]

Afternoon all,

As the sun is shining, and Covid-19 has given me some free time at home, I am using it to fix some of the minor little things on my S211.

I have a dull knocking/tapping at low speed over rough surfaces. I have found no play testing all of the bushes/ball joints/drop links with a large screwdriver as a pry bar, so I am suspecting the strut top mount/bearing. It has likely been on the car for 11 years and 173,000 miles so it has had a good life.

Before I order, a second opinion would be nice. Anyone know if the part highlighted is the one that tends to produce the knocking?

Many thanks,

Martin.

 

[merc85]

The rear ARB links did that on my s211

 

[pmcgsmurf]

In my experience you need something the size of a crow bar to see the movement in the bottom ball joint sometimes.

 

[MJJ]

Thanks both. I neglected to mention the knocking is in the OSF suspension.

I have put some fair force through the various bits using an 18" screwdriver. Probably not full crow bar, but I am pretty confident it is not any of the joints/bushes. That statement is going to come back and bite me now for sure

Martin

 

[OneForTheRoad]

All you can do is change it and live in hope. The shocks themselves can knock. As well as the several links.ball joints and bushes.

 

[Petrol Pete]

Long screwdriver not enough. you need a breaker bar or a crowbar and a big set of 'water pump' (gas) pliers to check properly, there is also a nifty tool which is basically a knurled metal cylinder about 40 x 300 mm with a 1/2 socket end on it. You drive on to it 'longways' and using a breaker bar on the end you can move the wheel on its vertical axis and it shows up any wear on the links. i will try to find a photo of it. I think its a Sealy product. I wouldn't order anything until you find out exactly what the problem is.

 

[Petrol Pete]

^^^ The Sealy tool I refer to is : VS3816 'Suspension Roller Bar' £21.54 incl VAT

 

[MJJ]

^^^ The Sealy tool I refer to is : VS3816 'Suspension Roller Bar' £21.54 incl VAT

Thank you PP, that looks quite a clever gizmo. I tried some more yesterday evening with a long breaker bar, and I cannot get anything to show play/movement either wheel off, or levering the wheel from underneath.

I am beginning to understand why so many folks have started down the 'replace parts until it is fixed' route, though I am not doing that. I will wait until it gets worse, and/or I can categorically find the offending item.

Thanks all,

Martin.

 

[streethawk]

My 211 also does this and I can't find the offending item either. Changed torque arms and top and bottom ball joints. Iam suspecting the ball joint on lower arm that the drop link connects too. Not sure if you can replace the ball joint or it's a new arm. Passes not every time. Had this knock since I brought it and doesn't seem to be getting worse and that's 5 years ago.

 

[BlackC55]

I've not ever replaced a top mount on a 211. Some we look after have 400k on them.

The most common causes are the roll bar links (hard to see the play) and the shocks themselves.

 

[MJJ]

Afternoon all,

As the sun is shining, and Covid-19 has given me some free time at home, I am using it to fix some of the minor little things on my S211.

I have a dull knocking/tapping at low speed over rough surfaces. I have found no play testing all of the bushes/ball joints/drop links with a large screwdriver as a pry bar, so I am suspecting the strut top mount/bearing. It has likely been on the car for 11 years and 173,000 miles so it has had a good life.

Before I order, a second opinion would be nice. Anyone know if the part highlighted is the one that tends to produce the knocking?

Many thanks,

Martin.

Coming back to this thread a year later as I seem to have solved it accidentally, and it might help others.

Back when I started the thread, I tried all sorts of prying/forcing actions to try and diagnose play in a suspension component - nothing moved. I asked a garage to specifically try and find some slack too, nothing showed up. The dull knocking noise from the OSF remained, and I resigned myself to ignore it until it got worse and play could be seen.

Fast forward a year, and the NSF spring snapped, not a surprise on a 180k mile car. My local garage replaced both front springs a month ago, and the knocking noise has gone. What is truly odd (to me at least) is that only the springs were replaced, not the top mount bearing - just springs.

The spring as a source of knock makes very little sense to me. I removed the struts from the car myself so I know all of the securing bolts were perfectly tight, and evidence does suggest that the spring itself was the cause of the knock.

Martin.

 

[Petrol Pete]

Thanks for coming back to us with this MJJ