Hello there. Hoping for some guidance. I have a 1969 Bronco that was just completely renovated. The 302 engine is a rebuild and literally ever other component is new. It runs just fine with city driving, staying at around 180 degrees. However, if I let it idle or drive at slow speeds for more than 15-20 minutes it starts to overheat (upwards of 240 degrees and then I turn it off and let it cool down). The first time I drove it slow on dirt roads I didn't notice until it hit 246 degrees and the coolant was literally boiling in the reservoir. Scary. The coolant is a mix of mostly antifreeze, some water, and some Radiator Relief. The electric fan is a Derail 17" high output fan. The thermostat is a Robert Shaw 180. I have confirmed that the fan is coming on at 180 (actually a little lower). It is overheating without the A/C on and an ambient temp of only 55-60 degrees. This is a real problem because I mainly want to drive this thing on the rutted dirt roads near my house that require 2nd gear and no more than 15-20 mph. Any thoughts on what could be wrong? Many thanks for any thoughts.
(PS I would post photos but not sure how to do it on this forum??? Sorry, newbie)
(PS I would post photos but not sure how to do it on this forum??? Sorry, newbie)