Questions and Answers

Ford Aerostar Likes Milk Shakes Q. Hi Vincent: I have a 1991 Ford Aerostar AWD, 4.0 liter engine, 366,000 kilometers, automatic transmission, rebuilt about 100,000 kilometers ago, ABS brakes, P/S, A/C, cruise control and rack and pinion steering. I am a person who does small to moderate repairs to my cars. About two months ago I discovered that my power steering was starting to stick.

When I looked at the power steering fluid I discovered that the fluid was a milk shake color instead of the clear oil color. I first though that water had somehow gotten in the power steering system. I took the Aerostar to a mechanic and he told me water cannot get into the system and what might have happened is brake fluid may have accidentally been added.

He said this contaminated fluid had swelled the seals in the system and so I had the power steering pump and rack and pinion replaced, however by a different mechanic. Now a few days ago I have noticed a water coolant leak around my engine.

After removing parts of the engine I observed the leak appears to be behind the alternator. It is not a hose leak so my conclusion the water pump is failing. I have noticed an occasional squealing sound coming from this region.

So my question is, should I go ahead and replace the water pump? My second problem is the other day when I was checking out the coolant leak I happen to open the lid on the power steering reservoir and to my shock I noticed the power steering fluid had changed from red, the mechanic added transmission fluid instead of power steering fluid, to milk shake color!

When the mechanic had replaced the rack and pinion two months ago he connected the two rubber hoses bypassing the radiator. So how could water, or any other fluid, have contaminated the power steering system? Could the possible failing water pump be related to the power steering problem?

Thanks for your time and effort,
Franco

A. Bypassed the hoses to the radiator? He bypassed the transmission cooler. I would get them hooked back up correctly as soon as possible. The power steering system does not go through the radiator.

If the "milk shake" color is a tanish color, you have air in the system. The air can not be bleed out in the normal manner, it has to be vacuum bleed. A Ford dealer has the proper tool to do this.

You can fabricate one yourself if you have a hand vacuum pump. If not, it's probably not worth buying one, and the other things, for this one use.

Basically it is a large rubber cork, large enough to fit in the P/S pump filler neck, with a hole through which there is a metal tube. This gets connected to your vacuum pump. Here is the filling and bleeding procedure.

FLUID LEVEL TOP OFF - PROCEDURE:

1. Check and fill pump reservoir to dipstick FULL COLD or remote reservoir center mark.
2. Disable ignition by disconnecting the EDIS/DIS/TFI module or, for remote TFI, disconnect CMP/Hall Effect/PIP sensor.
3. Crank engine 30 seconds, check fluid level and add if required.
4. Crank engine 30 seconds while cycling the steering wheel lock to lock.
5. Check fluid level and add fluid if required.

CAUTION: DO NOT HOLD STEERING WHEEL ON STOPS.

AIR PURGE WITH VACUUM EXTERNAL SOURCE - PROCEDURE:

1. Tightly insert the rubber stopper of the air evacuator assembly into pump reservoir.
2. Reconnect connection used to disable ignition and start vehicle.
3. Apply 20-25 inches maximum vacuum for minimum of three minutes at idle; maintain maximum vacuum with vacuum source. Refer to Figure 1.
4. Release vacuum and remove vacuum source.
5. Add fluid to FULL WARM or reservoir center mark.
6. Reinstall vacuum source and apply 20-25 inches vacuum.
7. Cycle steering wheel from lock to lock every 30 seconds for approximately 5 minutes.

CAUTION: DO NOT HOLD STEERING WHEEL ON STOPS.

8. Shut engine off, release vacuum and remove vacuum source.
9. Add fluid if necessary and install dipstick or reservoir cap.
10. Start engine and cycle steering wheel from lock to lock every 30 seconds for approximately 5 minutes.

CAUTION: DO NOT HOLD STEERING WHEEL ON STOPS.

11. Check for oil leaks at all connections.

And if the water pump is, indeed, leaking, then by all means it must be replaced.