Volvo Repair: 90 Volvo 240 DL - Overheating, volvo 240 dl, upper radiator hose

Question
My son is driving a 90 Volvo DL that wants to overheat.  Seems like the coolant level, radiator, etc are in good working order.  Wondering if it might be the thermostat.  How do I replace it?  Big job?  Because of the heat transfer thing is it possible for this to be exhaust related?

Answer
Check the face of the radiator for dirt and debris.Thermostat isn't hard to change its in the housing at the engine at the end of the upper radiator hose.Also there is a circuit board (Temperature compensation board)in the instrument cluster that will cause a false hot reading. this board can be bypassed or replaced.