Volvo Repair: S80 knocking noise, control arm bushings, lower control arm bushings

Question
I have a Volvo S80 2.9 auto which has done 118,000 miles - I have a noise when I first set off which is a knock. I have replaced the top engine mount as the rubber had broken down & I thought this would have cured it. Is there another rubber that I also need to replace?
I also have a popping noise coming from the front left which occurs whilst going over bumps whether I'm cornering or not - I've heard about Volvo supplying a larger than standard 'O' ring but not sure which part this is or if it is causing my problem. I've also read about top suspension mounts causing this noise.
Can you help?
thanks

Answer
I am almost certain it is suspension related.  The top strut mounts do break all the time and when they go bad you will hear PLENTY of clunking noise.  It will star small and gradually get worse.  Also on that model the sway bar endlinks go bad alot too.  That will give the same kind of symptom.  Also common (but not as common as the others) is that the lower control arm bushings will crack, and then make a clunking sound.  Have someone take a good look over the vehicle and they are bound to find something.  Be sure it is someone who knows volvos or they really won;t know what to be looking for.  The larger o-ring is for the subframe mounting bolts, and there are also ones for the axles bolts.  Either one of those could cause a noise but will not cause any damage to the car.  The other components are much more important and will affect the performance of your suspension.

James