My old 740 started rattling badly underneath. At first it sounded as though the exhaust was dragging on the road, but it wasn't. In fact, I couldn't see a thing wrong underneath. Then I thought it might be a stone caught behind one of the steel wheel trims. Nope.
Handbrake linkage caught up somewhere? No.
Exhaust silencer breaking up inside? Could be. Thumping the exhaust system I found that the middle silencer rattled badly. Fearing the worst I checked all around it and found...a broken rubber mount. A quick repair solved the problem and tomorrow I'll buy some new mounts for it.
Somebody here said that Volvos give expensive-sounding symptoms which are often fixed by spending very little!
Si