What are the signs that it is running warmer than normal? Many "overheating" cases are simply a bad gauge or sending unit. On my 83 the only parts of the radiator I can access to detect their temperature are the end tanks, and these won't tell you much about blocked tubes in the core. You need to get a thermocouple or something right into the fins to know for sure.

I've never heard of a gen. Volvo water pump failing to pump - yes they can develop leaks on the shaft seal. The problem then is that they are replaced with an El Cheapo with a stamped sheet metal impeller which cannot be as efficient as the Volvo die-cast hydrodynamic vanes. They have "cavitation" (engineering term for "froth and bubbles") written all over them. Also look more prone to coming apart.

Your car is getting to an age where the rad may need a professional cleanout. good news is the 240 rad is a piece of cake to pull out...half an hour your first time, and 10 minutes your second.

In my experience the Volvo t'stats are very dependable. Mine climb very slightly above "normal" after warming up, then drop back to normal, and hardly move at all after that, unless climbing a long hill in hot weather with AC going. I've only seen the heater affect the temp gauge on a VERY cold day with engine at idle.
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Bob (81-244GL B21F, 83-244DL B23F)