2003 GMC Yukon over heatimg

Hello, Have you pressure tested your cooling system, Does your coolant level remain the same? Or do you have to add coolant every so often. It s very common for a cooling system to overheat in this fashion when there is even the smallest leak, too small to be noticeable, because the heat just causes any escaping coolant, however miniscule, to evaporate. Because the coolant's boiling point is kept in check by pressure, any compromise, no matter how small can cause the system to lose pressure and boil the coolant. Under less of a load also pressure may not be great enough to show coolant leaking. So check to see if coolant level remains the same, and try pressure testing the system.