As a teen, we had a '71…
As a teen, we had a '71 Chevy Impala 350 V-8. It developed an overheating problem. The radiator fan had a fan clutch which varied the fan rpm based on ambient temperature. My dad and I couldn't figure out the overheating. The only clue was the overheating occurred when driving in town, decreased airflow. The car I had when in college was a 1966 Chevrolet Caprice (bought used) 4-door hardtop 396 V-8. It had dual exhaust, a four barrel carb and was rated at 325 hp. I get nervous just thinking about that hunk of American iron. In an attempt to diagnose the Impala's overheating my dad suggested parking the cars side by side with the engines running at operating temperature and hoods up. We noticed that the '71's radiator fan was running at a slower rate than the 66's fan. We replaced the fan clutch on the 71 and it never overheated again.