Member II
That's the first thing we're checking tomorrow. We're going to take an inferred temp reader to take pre and post t-stat reading to determine of coolant is making it through the radiator. We're also going to check the sensors to make sure they're reading correctly. My thought was maybe a sensor went out after around 450 miles on the new engine since everything was running fine before that. We drove about 50 miles to the inlaws with no issues, and then out of no where we had issues.Just a thought, perhaps stupid, but are you sure your temperature gauge is giving you accurate readings? Back when I was in high school, I had a 1976 VW Rabbit (don't judge). At one point I thought it was starting to overheat all the time and chased all the same symptoms you did. Turned out it was the temperature sending unit that had gone bad.