ZF Pump

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

NOTE: This procedure is for motorhome vehicles equipped with either the Hydro-Boost or Hydro-Max Brake Systems.

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

Remove the reservoir cap. Check the fluid. See Figure. Use Motorcraft MERCON® Multi-Purpose ATF XT-2-QDX or MERCON® equivalent.
Tightly insert the stopper of the vacuum pump into the reservoir.
Start the vehicle.
Apply maximum vacuum and maintain it for a minimum of three minutes with the engine speed set at idle. See Fig 1.

Fig 1: Applying Vacuum To Power Steering Fluid Reservoir (ZF Pump)
Courtesy of FORD MOTOR CO.
Release the vacuum and remove the vacuum pump.

CAUTION: Do not over fill the reservoir.

Fill the reservoir. Use Motorcraft MERCON® Multi-Purpose ATF XT-2-QDX or MERCON® equivalent.
Reinstall the vacuum pump. Apply and maintain maximum vacuum.

CAUTION: Do not hold the steering wheel against the stops for more than three to five seconds at a time. Damage to the power steering pump could occur.

Cycle the steering wheel fully to the left and right every 30 seconds for approximately five minutes.
Stop the engine, release the vacuum, and remove the vacuum pump.
Install the reservoir cap. See Fig 2.
Check for fluid leaks at all of the connections. If the power steering fluid shows signs of air, repeat this procedure.

Fig 2: Installing Power Steering Reservoir Cap (ZF Pump)

Courtesy of FORD MOTOR CO.