Originally Posted by
Hondarally
Highway driving should put a very low load on the cooling system. You're only drawing about 20kw at100, and have bulk air flow. To be overheating under those conditions means either
A) radiator blocked (classic symptom tho unlikely if rad is new)
B) airflow bypassing the rad as mentioned before
Block off excess openings
C) water pump farked. Not drawing enough coolant through the system for proper heat exchange
D) inside of engine caked with scale forming an insulating layer.