My Volvo S80 turbo 2001

When the temp gage gets to the half way mark or past it, does the fan come on? If it does not you could have a faulty radiator fan. Before you replace it, call Volvo and see if recall 141 was done. If it has not, have them do it since that recall is to inspect and replace the radiator fan. Not all fans had quailified for replacement based on there part number but it is worth a shot.

Well looks like you have replaced just about everything but the heater core? If the system is plugged up it could be in the block? Or you could have a blown head gasket at this point. You may want to do a compression test and a cylinder leak down test.