My civic x 2017 drives fine in city, no issues. It starts heating up when i rev a bit harder for a bit. Starts heating up on incline, even on salt range. Temp gauge goes back to normal after 30-40 seconds of light rev or stopping the car. I recently did a lahore to hunza trip, whenever theres an incline the car starts heating up. I had to stop 3-4 times for a minute or two while ascending babusar. What issue is this? My mechanic hasn't been able to understand it yet