Compression Ignition Addict
Join Date: Jun 2010
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It sounds like you have identified your problem. The power steering pump provides fluid to your gearbox and hydro boost. When you apply brakes, the steering becomes more difficult b/c your pump is supplying a fixed amount of fluid to your gearbox and hydro boost at idle. When you raise your RPMs it flows more fluid and voila your steering works better.
This should not be an issue with a stock truck when everything is functioning correctly. Since you have replaced your pump and gearbox, the next logical part is the hydro boost as you have mentioned however, they are not cheap.
Have you noticed any fluid leaking from the hydro boost, inside the cab where the plunger enters it?
Have you bled everything sufficiently to make sure there is no air trapped in the system?
What type of fluid did you fill the system back up with?
The factory puts ATF in the power steering pump. Since you have changed out the pump and gearbox, you have essentially drained the entire system (with the exception of the HB)
'99 7.3L PSD, F250 SRW, BTS, 2.5 Ton Rockwell Axles
'02 7.3L PSD, F350 DRW, 6spd, IH Up-Pipes, 4" MBRP