Timing belt?

My father has just bought a late 95 build 850 S. We have been tracking through the handbook and service book and cant find any details on how often we need to replace the timing belt (assume it is a belt, not a chain), also can't figure out which engine we have. what is the easiest way of telling this?

Log book or engine code number which should be on a sticker on the cam belt cover. Belt changes should be every 80k, but if you have no history you should do one asap. The engine code will start B4 or B5 and have three more charatcers, the first character being the number of cylinders, the second and third the engine size and the fourth the number of valves per cylinder. Otherwise ring Volvo UK (or any dealer) and they should be able to give you all the detals.

thanks, it is the number of valves that we are interested in (we know the basics of teh specs), has the fully stamped logbook upto 195000km but there is no tick boxes or anythign in the logbook to tell you when things are meant to be done.

just found the numbers, it is a 10 valve 2.5, can anyone tell me what the S means at the end of teh code? (ie: B5252S)