1995 C280 Knocking noise OSF

[Ron Palfrey]

Car has developed a light knocking noise at the offside front when travelling slowly over any road surface that is not perfectly smooth. Doesn't happen for first 10 miles or so but then starts. e.g. pulling up at a red light gets a knock as I come to a stop and the suspension compresses, then a similar knock when I pull away and the weight transfers from the front suspension. Once it starts there is a clonking over rough surfaces at low speed.
Can't feel anything through the steering, car steers fine, no vibration, just this dreaded low speed clonk.
The noise isn't noticeable at faster speeds, just at town speeds of say 30mph or less.
Anti roll bar bushes look in good condition. Bush at bottom of shock absorber looks OK too.
The usual shocker test by pushing down on front wing makes no noise when cold. However, if I pull up when the noise has started after 10 miles or more, the same test creates the clonk when I press down and when the car comes back up.

Anyone else had this problem? If so what was the solution please?

I'm off to France in a couple of weeks and I would like to sort it before I do 3000 miles in the space of a fortnight.

Many thanks in anticipation of your help / ideas,

Ron

 

[akz786]

SNAP - on my 1995 c180 auto exact same problem im going to try ramp it up weekend to see..sorry that I cant help, just strange im having same issue as you!

anyone can help?

 

[television]

I have taken away what I said as I was wrong on the links

 

[BlackC55]

I think it is the anti roll bar links, you need to lever them to find any play

They don't have any on a 202.

Look at:

Springs

Chock absorber

Roll abr bushes

Camber/castor bushes.

 

[Ron Palfrey]

Thank you for your suggestions BlackC55.
Spring looks OK, no signs of a break and it seems seated OK too.
Shock absorber - can't see top mounting - I guess it's under the air filter housing, so will take that off tomorrow to check the top.
Anti roll bar bushes look ok.
I take it that the camber/castor bushes are the lower arm front and rear pivot bolt bushes? Doubt if I can check those by sight only and they look as if they'll take some levering. Any tips?
I will investigate and report back.
Good luck akz786, sorry to hear you've got the same problem, but glad I'm not alone with this one. Let me know how you get on please.
Regards,
Ron

 

[Ron Palfrey]

Raining too much to look at car tonight. Used it for two 5 mile journeys today - not a sound from the suspension! But if I'd have gone 15 miles I know it would have started to clonk.

 

[BlackC55]

I'd be putting money on the shock absorber.

You can drive it without it fitted. Its a bit bouncy but it will eliminate it.

 

[Ron Palfrey]

Thanks for that BlackC55. I'll feed back in due course.

Ron

 

[Ron Palfrey]

As it's been a nice weekend I managed to take a look at MY car in between working on my daughter's AX. What a pleasure to get back to my C280. The Citroen was a challenge in terms of working space around the engine.
Firstly the OSF shock absorber mounting is NOT under the air filter housing, it was staring me in the face just behind the coolant header tank. No dismantling to get to it. Anyway, I took the car on a 10 mile run to get the knocking noise started, pulled up on my drive, popped the bonnet right up, did the bounce test with one hand on the top mounting and I could "feel" the knock. I made sure the top mounting was done up tight (which it was) so it looks as if I've got to buy two new shock absorbers and fit them before we depart for France. The car has done 103k miles.
I did notice that it is difficult to get a spanner on the bottom nut to undo the top locknut because space is restricted. The spanner needs to be slim and short. Furthermore the top of the shock absorber rod protrudes a long way through the nuts (by about 25-30mm which makes it difficult to use a standard length 17mm socket. In the end I used an open ended spanner to hold the bottom nut and a 17mm BOX spanner on the top nut, with a conventional socket on the other end of the box spanner to turn it. Otherwise it would be difficult to use a torgue wrench to get the torque setting right.
I wonder whether akz786 has investigated his similar problem further and reached a similar conclusion.
Ron

 

[Ron Palfrey]

Have spoken to a local garage who says that the noise is likely to be movement of a valve seat within the shock absorber itself. The noise appears when the shock absorber warms up after a few miles. The performance of the shock absorber is not affected. Just the annoying noise at low speed. It is recommended to replace them in pairs so the cost of the parts would be £55 x 2 = £110 from GSF in Leicester, or £87 x 2 = £174 for Boge units from AVP in Market Harborough. As most of my 3000 miles across France will be at higher speed I'm keeping my money in the bank ftb. MOT time comes up in August so will leave any necessary replacements until then. I'm taking my toolkit with me to France and if the noise gets a lot worse over there then I'll buy shockers over there and fit them. Simple enough job. I'm just too tight to do it now while I can put up with the low speed knock, especially as it is not safety related.
Thanks for your input guys.
Ron

 

[akz786]

thanks for that input i havent even had the chance to look into this yet as its my dads car but the symptoms are the same i went under the car could not see anything loose or that would knock, im going to check again as i feel its clunking/knocking from the OSF as you mentioned.

I might check the shock absorber too allthough mine does it from the start too so may not be this.

thanks

 

[BlackC55]

Look at the lower ball joints.

 

[Ron Palfrey]

Well, 3000 miles later I'm back from France and the knocking noise has subsided. That constant intensive use has obviously settled down the problem with the shock absorber. Car has gone in for MOT test today and sailed through with no problems whatsoever.
Ron