Purging System Of Air

CAUTION: If the air is not purged from the power steering system correctly, pump failure could result. This condition can occur on pre-delivery vehicles with evidence of aerated fluid or on vehicles that had steering component repairs.

NOTE: A whine heard from the power steering pump can be caused by air in the system. The power steering purge procedure must be carried out prior to any component repair for which power steering noise complaints are accompanied by evidence of aerated fluid.

Remove the fluid reservoir cap and check the fluid. See Fig 1.

Fig 1: Checking Reservoir Fluid Level
Courtesy of FORD MOTOR CO.
Tightly insert the stopper of the vacuum pump into the fluid reservoir. See Fig 2.

Fig 2: Attaching Vacuum SourceTo Power Steering Reservoir
Courtesy of FORD MOTOR CO.
Start the vehicle.
Apply maximum vacuum (20-25 INCH-Hg) for a minimum of three minutes at idle. Maintain maximum vacuum with the source. See Fig 3.

Fig 3: Using Vacuum Tester To Purge Air From Power Steering System
Courtesy of FORD MOTOR CO.
Release the vacuum and remove the vacuum source.
Add fluid to the appropriate level. Use Motorcraft MERCON® Multi-Purpose (ATF) Transmission Fluid XT-2-QDX meeting Ford specification MERCON® or equivalent.
Reinstall the vacuum source and apply vacuum. See Fig 3.

CAUTION: Do not hold the steering wheel in the far left or right position or damage to the power steering can result.

Cycle the steering wheel from stop-to-stop every 30 seconds for approximately 5 minutes.
Remove the vacuum source from the fluid reservoir.
Turn the engine off. Check the fluid level and fill to the full warm level. Check for leaks at all connections. Install reservoir cap. See Fig 1.
Start the engine. If there is any sign of aeration or if the fluid level in the reservoir drops more than 3/8 inch, turn the engine off, and repeat the procedure.