I just purchased a used 2000 S40 and besides the previous owner being a smoker (clearly not Volvo's fault) I only have one thing wrong with it: whenever I drive over a bump the I hear a metallic clonk noise like a light metal part hitting another. It seems to come from the center of the dash or the passenger side. I tried to hold/feel the dash but it didn't change. I can't really see the dash vibrating or moving, it doesn't seem loose but I can't be sure. It does not sound like the sound is coming from the suspension, If not from the dash then maybe from the engine compartment right on the firewall.
Does anyone have similar noises or an idea what it could be? I hope I don't have to take the dash out to fix it.

 

I don't think this is in the dash, it is more then likely the front passenger suspension. It just sounds like it is coming from the dash because of you being in the car. Anyway, more then likely the anti-swaybar endlink is bad or the spring mount. I would take a look at both and go from there.

 

Thanks for the advice. I will put new brake pads in on Tuesday anyway then I can take a closer look at the suspension. When I am down there, what am I looking for? Obvious play or visibly worn out parts or is it one of the "replace it and see if it was that" kinda problems?

 

+1 on the swaybar link. Just take the wheel off and grab the link and shake it firmly. If it rocks and makes noises, either tighten it (if loose) or replace it. Cheap to do, take you about 30 minutes. Link may look worn (as in leaking a bit of grease out of the fitting or little rubber cover is torn), or it may look fine. Once you get the link off, check the play of the ends of the link, see if it still has some good resistance to you moving it or if it is "played out" and loosey-goosey. I did the links on my 2000 S40 about 3 months ago, and the 2 squeeks and one loud clunk from my suspension area was completely resolved. Sounds like your metallic "clonk" is just like my metallic "clunk". My clunk also happened only when I went over a bump, and the sound was lod enough to hear well. Good luck.

 

Seems like the swaybar endlink is a common problem on this car. It's not expensive ~$36. I will check it tonight and then most likely replace it tomorrow. Can anyone tell me the torque specs on that please, my Haynes manual is still a few days from delivery.

On the way to work today I discovered another problem. When accelerating from high speeds (60) to higher speeds, especially uphill, the car starts shaking and vibrating. When letting off the gas or going downhill it's gone. So far I think it is probably one or both cv joints. If that is the case I might replace the half shaft assembly. Am I far off? What damage will it cause if I keep driving for a few more days?