Car is running hot.

What is your question?

I have a 1999 Nissan Pathfinder. I'm having a problem with it running hot. If I drive somewhere within 15 miles, it runs at normal temp, but it seems like whenever I drive further it runs hot. My brother says there's no pressure in the cooling system. I bought a new radiator cap, and we vacuumed the radiator out thinking there may be an air pocket. Neither have worked. I bought a thermostat for the car, but I don't want to put it on if it's not the problem. I've also noticed a crack in one of the air intake tubes. Was wondering if that could be the problem. Any help would be appreciated.