So I have a 1980 Buick regal with a Pontiac 265 v8 mated to a th200.. I am having issues with the cooling system. I have replaced a dozen thermostats and 3 radiators. and 3 aftermarket coolant temp gauges.... when I fly up to 60 mph coolant will go through the cap and only push coolant out into overflow and out of that.. To me it seems as if there is too much pressure not allowing it to circulate. I start the day with the radiator overflow full and I end the day with an 4/5 empty radiator and no overflow.