Regarding my 2004 MCS (58k miles), should the fan for the power steering pump be running anytime that the pump is on?
If it should be running but is not, is it likely to be a simple fan replacement or likely another (electronics?) issue?

Is there any risk of damage to the steering system if I drive when the pump is not working?

Background for the questions: Power steering went out (very heavy steering and no whine from the pump) in the ninth hour of a road trip (it was about 100 F at the time). The next day I turned the car on and the steering feels fine. Looking under the car while it is running, I see that the fan is not turning. I did not drive or otherwise heat up the car to see if things changed.

From what I read in numerous power steering pump threads, I think I’ll replace the fan, then take out the pump and clean it up. Sound reasonable? Will it hurt to drive it for a few days while I wait for the replacement fan?

 

The fan runs independent of the pump. In fact, there is no temperature sensing in the pump used to activate the fan. The fan under the car exists not really to cool the PS unit, instead, it's there to keep the heat from the header/catalyst from overheating the pump. The pump itself will shut down if it gets too hot internally. There is an electronic control/regulation circuit inside the motor housing that is the most sensitive to heat. The way the MINI cooling system is set up, any time the main (radiator) fan switches to it's highest speed, the PS fan comes on to counter the amount of heat being blown down from the header area. When driving, there is enough cool air moving along under the car to keep the PS pump assembly cool (make that 'within specs'). Long jaunts on the highway with the a/c running build up a lot of heat, when you come to a stop, the main fan will often kick in it's highest speed and the PS fan comes on to keep the area around the pump from getting out of hand.

If your car has alignment issues that force you to keep a light tug on the wheel to keep a straight track, this will cause the pump to run in a higher power mode (it's variable according to effort needed). Over time this can overheat the pump as well.

 

Wow. Thanks for the great details. Any idea if my pump's shutting down is indicative of a looming problem? Anything to be done or just wait and see?

When it shut down earlier I had been maintaining 70+ mph for hours so there should have been plenty of air flow (albeit > 100F).

 

Jvw were you driving on crowned roads? I know where i live the frequent rain causes the need for the road to be banked outward in both lanes. If you came from a dry climate and were driving on roads such as these, then maybe you experience what Greatbear was talking about with an alignment issue

 

Well, the pump went out again this morning after 15 minutes of easy driving in 75 F weather. However, it lasted for 30 minutes before it went out this afternoon at 90 F.

The large majority of mileage is on good highways and requires very little steering input. The crowning is negligible.

I still wonder if there is any risk of damage to the steering system when driving w/o the pump working. It seems to take a great deal of force to turn the wheel.

Tonight, I intend to take the pump out and clean it up and look for any obvious problems.

 

If your having pump failure, i would suggest getting a new and or having it looked at ASAP. I had a 1969 Cadillac DeVille that lost it's pump in the middle of a turn, a not so enjoyable experience at slow speed, and i cant imagine what a mini would do ina turn without assisted steering.