Technical Intermittent suspension clunk 2009 1.3 Multijet.

[DaveMcT]

I have an annoying clunk from the left side front. It happens over some bumps and sometimes when making a right turn. But it’s hard to replicate.
The struts are not new but damping feels good.
Top mounts have new bearings. Steering is smooth.
Road springs are new from S4P
Drop link joints are not worn.
Bottom arms were swapped. No change.
Strut top nuts are tight.
I have replaced a few struts but never had an issue.
No visible witness marks.
Gearbox engine mount is new. No change
Gearbox Dog Bone rubbers look ok but it probably does need renewing. Getting suddenly off throttle is harsh but does not make the noise.
The 1.2 petrol made a jingling noise when its drop links joints failed. This is nothing like that.
Brakes fully checked over. Nothing loose. Wheel bolts ditto.
Exhaust is not catching anywhere.

Any ideas?

 

[jrkitching]

Drop link joints are not worn.

If anyone else had posted this, I'd suggest they double check it before doing anything else; it's easy to be fooled if there's any tension or compression in the droplink.

You can't test the droplinks for play with the weight of the car on its wheels, and you can't test with the car jacked up and the suspension hanging free either.

You first have to jack up that side of the car, and then jack under the strut, compressing it just enough to unload the anti roll bar. Only then will you be able to easily feel any play.

But in your case, I'd be surprised if you missed this, and in any event, I'd expect worn droplinks to be less intermittent in their effect. However, this might help someone else in the future.

You've already checked all the stuff I'd have thought of as a possible cause. As you say, it's a head scratcher.

If you had been driving extremely hard over rough ground, it's possible the strut might unload enough for the suspension on that side to drop onto the bump stop - there's usually a small gap between the bump stop and the bodyshell (which is normal), so I'd expect you'd hear this. But this is even less likely in a diesel, with the heavier engine putting more weight onto the front wheels. This would, however, explain the very intermittent nature of the sound. You could probably replicate this by vigorously shaking the roadwheel up & down with that wheel jacked up - but make sure it's well supported! On some cars, there's often quite a bit of play between the top mount and bodyshell in this situation, but it's only an issue if the play is still there when the weight of the car is on its wheels.

 

[irc]

I did replace a pair of front dampers an an MJ to cure a random annoying thunk. Damping seemed OK, and they weren't leaking. Once off I could recreate the noise by extending the damper.
The ones I took off looked almost new, but passenger side was definitely internally shagged. Not sure what brand they were, but had the look of "cheap & cheerful" ebay specials (too much paint, sharp edges, etc.).

Otherwise all noises have been the usual suspects, which you've already checked out...
Drop links (over almost all bumps)
Top mounts (along with notchy steering)
Rear bushes (metal on metal thump, and clunk when changing direction of travel).
Dog bone (thump when going on/off throttle)

The MJ does give front dampers (and lower arms) a harder time, so I always use best brand available at the time.

 

[bugsymike]

If it's a dull knock then possibly the anti roll bar mounts in the subframe.
If it is a metallic knock I have had lower wishbone inner bolts tight, but bush moving in the subframe.

 

[DaveMcT]

It’s a dull thud - worst when going a bit quick (but not idiotic) around a mini roundabout.
I have had it happen on the really steep car park speed bumps but couldn’t replicate it.
I’ve have had knackered shocks that went loose near full droop. This seems to be worst when it’s compressed.
IIRC the drop links were swapped left/right no change. But I might have made that up.
I did find worn rubbers on the bottom ball joints but thankfully no damage. I have new rubber boots to get fitted.
I’m trending towards a pair of shocks and drop links (might as well) from S4P but it’s a fair wedge only to find it’s not fixed.

 

[bugsymike]

It’s a dull thud - worst when going a bit quick (but not idiotic) around a mini roundabout.
I have had it happen on the really steep car park speed bumps but couldn’t replicate it.
I’ve have had knackered shocks that went loose near full droop. This seems to be worst when it’s compressed.
IIRC the drop links were swapped left/right no change. But I might have made that up.
I did find worn rubbers on the bottom ball joints but thankfully no damage. I have new rubber boots to get fitted.
I’m trending towards a pair of shocks and drop links (might as well) from S4P but it’s a fair wedge only to find it’s not fixed.

When the car is on level ground on full lock it may be possible to see the inner antiroll bar mounts and maybe see if a bar can produce any movement.
Sometimes it can be felt through your feet against the floor/bulkhead area.

 

[DaveMcT]

I’ve had a go at that this morning. Need to make time to remove the wheel. this all seemed ok when the car was resurrected but it’s done a few miles since then.

 

[koalar]

Loose droplink nuts would be my gues

Drop link thread is smaller than the holes it goes through

As you are going round a roundabout one side is compressing

Unless the nuts are properly tight they slip inside the hole and make one thud

Pretty common, from back street mechanics or dIYers

Normally it takes awhile, from fitting the drop links to the problem appearing, Usually ending with new drop links being fitted again.

You can really do them up by feel, to loose and they clunk too tight and they strip, there's not much leeway

 

[AndyRKett]

I had a very similar thing on my Mk2 Punto, where a torn ball joint boot had let grit and grime in and the ball joint was loose in the socket. only made the noise in certain situations but obvious once the car was jacked up and the wheel wiggled

 

[The Panda Nut]

It’s a dull thud - worst when going a bit quick (but not idiotic) around a mini roundabout.
I have had it happen on the really steep car park speed bumps but couldn’t replicate it.
I’ve have had knackered shocks that went loose near full droop. This seems to be worst when it’s compressed.
IIRC the drop links were swapped left/right no change. But I might have made that up.
I did find worn rubbers on the bottom ball joints but thankfully no damage. I have new rubber boots to get fitted.
I’m trending towards a pair of shocks and drop links (might as well) from S4P but it’s a fair wedge only to find it’s not fixed.

I had knocks after doing work on our 169. I stripped it and double checled the bottom plate was exactly right and made a very small adjustment which did the trick. I would check that the spring cannot move as its currently set, not easy but worth a try. If it came on a while after your springs were done maybe a stone had got into the set up somewhere?

 

[DaveMcT]

I’m doing some engine work. My fault entirely I rushed the valve job. When jacking it up I had my hand on the tyre as it unloaded and skidded inward. All normal stuff. I heard the clink and felt it. I’m 99% sure it’s at the top of the shock. No time yet to get it off the car. But at least that’s some progress.