For some time, I've been seeing 85 degree cooling system temps, reaching up to 90 on warm days. Even when it's cold out, I still see 85 degrees C. It used to to peak at 80, even on warm days. So, I put in a new radiator, new thermostat, and tested the aux pump. Everything should be perfect, but I'm still seeing 85 degree coolant temps, even on near-freezing days.

Today, I took my thermo gun and aimed it at the radiator, with the vehicle stationary (of course). I'm seeing 78C near the inlet, and 23C near the outlet. Most of the radiator reads much cooler than the 78C inlet temp. The outlet hose feels cool. Could this be a flow problem? The water pump was replaced at 109K, 16 years ago. Could the pump vanes have eroded? Or should I look elsewhere? I'm wondering if I might have missed removing a plastic plug when I installed the radiator...

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Rob