Why did it overheat going uphill?

if it has a viscous fan hub( fan clutch ) check it for correct operation
what you describe indicates that the fan is not travelling as fast as it should to be pulling air through the radiator
other indications are temp rising at stop lights , temp rising in slow moving traffic or in your case loaded ( going up hill)with higher engine rpm

Sounds like a possible heater matrix leaking in side the car and loosing water hence the temp goes up and a film on inside screen

Possible thermostat faulty, Thermostat automatic, stays shut, till water reaches correct temp, if it goes faulty, (ie) does not open after reaching running temp, water will not circulate, so engine overheats

If your vehicle doesn't actually overheat, just getting hot, I think that's the normal behaviour for these cars. My 03 AWD behaves the same way. When driving uphill, especialy when towing, the temperature rises close to the red marking, but I have never experienced it overheating. I think that the temperature has to rise much over the normal driving temperature to activate the two electric fans.

Hi,
You did well by shutting down quickly.
Why did the water come out when you stopped after the fan belt broke???
Residual engine heat. The engine has fiery explosions going on in the cylinders. Very hot.
Antifreeze flowing through the water jackets of the engine carry this heat away. Fan belt breaks, water pump stops pumping this very hot coolant away, engine temp goes up.
Thus the coolant temp rises enough to boil and push the coolant past the pressurized radiator cap out the overflow onto the ground.
I would recommend a fifty fifty blend of antifreeze and water for coolant. It just cools better.
Not seeing any leaks is very good. Smart thinking on your part saved you money.
Wayne

It could be the water pump , or something else , like a faulty thermostat. Where is the coolant leaking from ? If it is leaking from the water pump , then yes , your pump might be toast.
If the thermostat is no good , the engine will warm up to normal temp , and then overheat quite quickly. As it overheats and the coolant expands and boils , it could back up into the overflow reservoir and leak out onto the ground. You need to get someone to diagnose the problem ASAP , running your engine in an overheat condition could very quickly blow your head gasket and/or warp a cylinder head. If you can , please post a bit more info. Does it run but at a higher than normal temp. Does it only overheat when stopped in traffic etc.
Could be water pump , or thermostat , or plugged up radiator , or nonfunctioning cooling fans.

Try the overflow tank cap. The seal will go bad and not hold the psi causing the water to flow out this is something you will not always see which will cause the engine to overheat or temp gauge to rise. Also the thermostat could be sticking and cause the temp gauge to rise. Are the fans turning on when the temp gets high? If so then I would resort to the above first. If the fans are not coming on, the relay or fan/s could be the problem.

radiator may be partialy blocked, will overheat mostly on long uphills.

hallo
check water cooler (mud, dirt...) Usualy betwin ac condenser and water cooler. Clean with high preasure (karcher...).
if this is not the problem, go on a spin with diagnostic equipment and check water temperature. if temp. is ok and on dash water coolant light flashes, replace water collant sensor.
hope it helps
Marko

Whats the temp?How do you know its overheating