Is the bearing noisy or is there play in it? There is an oil seal installed at the same time as the bearing - my suspicion is that this is the problem (possibly not fitted correctly?) Mike

I haven't actually checked what's happening yet, I was just trying to prepare for what might be needed. Last time I assumed the oil seal had been compromised due to the play in the bearing (it had a lot of play but did not make any noise when driving that I noticed). Can the oil seal be changed without disturbing the bearing? It's perfectly possible I messed up the install but I don't remember the details.

oil seal 

oil seal has failed care in fitting seal needed any dirt or damage will shorten life of seal :thumbs_up:

One problem I have experienced in the past - not on Volvos (I've not had a wheelbearing go on one yet), is where the outer bearing case is a loose fit in the axle, which can happen due to damage if the bearing has seized or due to poor manufacturing tolerances if it's an aftermarket bearing. If you do get this problem it can sometimes be corrected by using 'stud and bearing fit' or similar, or in worse cases I've 'peened' the surface of the housing in the axle with a hammer - basically roughing up the surface to give the required tolerance. This may not be 'best practice' however, so I don't necessarily recommend it. Any looseness in the bearing can cause early failure, preceded by leaking seals. It may just be the seal on your car, but it's worth being aware of when you do the seals - as I don't think the seals can be done without renewing the bearing unfortunately.