2001 MPV van overheats only at high speeds

[ablservices]

2001 MPV Van will over heat at high speeds. Thermostat tested good, no airlock in system, fan is very noisy when running. Van can operate at low speeds forever and not overheat. One garage has said the fan must not be working correctly ($1200 fix). Needless to say I left. Please help. Any Ideas.

[itsme000]

Originally Posted by ablservices

2001 MPV Van will over heat at high speeds. Thermostat tested good, no airlock in system, fan is very noisy when running. Van can operate at low speeds forever and not overheat. One garage has said the fan must not be working correctly ($1200 fix). Needless to say I left. Please help. Any Ideas.

Your engine produces the greatest amount of sustained heat during highway driving. If your van is making 20hp at the wheel continuously, there is probably around 25-30kW(about 5-10 times the heat of a home water heater) dissipating into the cooling system. Fan is mainly for creating airflow when the vehicle is moving slow or stopped. When moving at high speed, most of the airflow comes from the grille cutting into the air.

Check things in these order:

1. Radiator is clean and free of excessive bent fins

2. Coolant should be lime green, yellow, or pale orange depending on the type of coolant and should be free of any particulate matters. If you see any solids or is brownish, have the system flushed and filled with 50/50 coolant. If its a 2001 and it hasn't been changed since delivery, you're due for a coolant change anyways.

If these looks fine or correcting these doesn't fix the problem, the problem maybe the water pump.

Let me know how it turns out