08 F250 Power Steering. HELP!!!

JoeR · September 25, 2019

A shop around the corner from my house has an 08 F250/6.4L. It came in with a broke belt tensioner and the serpentine belt wrapped and shredded around everything.

The belt got behind the power steering pulley and destroyed the pump seal. He ordered a new seal, blew the fuzzies from around the shaft, including what looks like a lube hole for the seal. Reassembled it and road tested. 5 miles into the road test there is an intermittent loss of power steering and brake assist. 5 more miles later and the pump starts screaming like it is cavitating, but there are no air bubbles in the fluid.

Bring it back. New Motorcraft pump. New ATF (what it calls for). Same thing happens.

Vacuum bled according to the repair procedure. When you apply vacuum to the system the pump stops screaming, but there is no assist at that time.

Relieve the vacuum, makes noise, get assist back.

So it gets a second Motorcraft pump. Disconnected the lines. Spin the pump with an air motor to bleed before installing the pulley. It looks good. Reinstall the lines. Vacuum bleed.

Good for another 10 miles, then it boomerangs. The pump is screaming again. There is so sign of air bubbles in the fluid. Just a very noisy pump.

We are at a total loss. Problem started with a broken belt tensioner. Any advice welcome.

Joe

cbriggs · September 25, 2019

I have seen the screen in the reservoir get plugged up and cause this, and also have seen the plastic liner slide in the pressure lines and cause all sorts of restrictions and weird noises.

JoeR · October 16, 2019

For anyone wondering, a 4th Power Steering Pump is what finally fixed this. When we put a clear return line on it, you could see that the pump flow would rapidly stop and start, making the noise. There was never any aeration of the fluid, but something was definitely failing in them. It's crazy to have had 3 bad ones.

Truck has been out there for 2 weeks now, so we are confident it's finally fixed.

Joe