Checked radiator water level. Level normal. Drove approximately 8 miles and vehicle overheated. Several hours later and after replacing water lost from earlier overheating, I drove approximately 20 miles (including 2 steep inclines) and did not experience overheating.
What would cause the inconsistent overheating?
Overheating can be caused by a few things like stuck a thermostat, loose fan belt (depending on year), cooling system being air bound, fan relay and or fan inoperative, bad head gasket.
A bad head gasket can fill the cooling system with air and causing it to be air bound. If you keep refilling the cooling system this condition should be checked.
A leak at the water pump will also cause an overheating condition from time to time if the coolant level is not monitored weekly. If you keep filling the coolant recovery bottle, see if you are leaving any coolant on the ground.
If you did a repair related to the coolant system the system could be air bound. Jack up the front of the van and support properly and chock the rear wheels or use ramps, this puts the radiator higher than the engine. With the engine cool, remove the radiator cap and run the engine and monitor the coolant level in the radiator. Fill the system when needed until all the air is removed.
If there is no other problem then this should take care of it.
Keep and eye on the coolant level. It still could be other internal engine problems if your vehicle is not leaving coolant on the ground.
Try these suggestions and get back to us when you can.
Try to leave more specific details like make, model, engine size and a detailed description of your problem.