Need help bleeding hydroboost steering system

[JoshHefnerX]

I recently swapped the pump/gearbox on my 7.3 superduty.

Got rid of the ford parts and went w/ a saginaw pump and psc gearbox.

Having a hell of a time bleeding this thing. Tried the 'manual' method of lock to lock several times and pumping brakes w/ engine off. Thought I made progress as the level was staying fairly consistent.

Started it - no noise. steering/brakes - same thing as 'manual' method above after letting it run. Level was starting to stabilize - only dropping 1/8" or so when starting.

Problems are after the last bleed cycle

1. It's aerating - fluid is 'milky' now.
2. hydrobost got spongy with engine on.

so I let it sit overnight to see if the bubbles would come out, the fluid cleared some, but not 'clear'.

Started over w/ 'manual' bleeding - and turning steering left/right causes the fluid level to rise in the reservoir if turned too fast and will overflow if, I dont stop mid turn. It will 'settle' after a sec or 2.

I'm not seeing any leaks at the fittings. hoses are all pretty new and clamps are pretty tight. I did replace o-rings on 4 of the 5 fittings when I did all of this.

Any thoughts, or is this the usual pain when trying to bleed hydroboost systems? Is there a better method to doing these?
I replaced the hydroboost about 6mo ago and didn't have a terrible problem, but I didn't try that hard as the ford pump was making some noise all the time anyhow.


I've not heard any whining when this was running, and saw decent movement in the reservoir.

 

[obijuank5]

At the diesel shop we would use a 12” ish radiator hose to extend the filler neck on the pumps and let the aeration run to the top without spilling over so we didn’t lose fluid. Light pressure on the brake pedal while full sweep left to right as per usual. Just letting the bubbles reach the top of the reservoir without getting recirculated was the trick.

 

[Wes Harden]

I really don't understand bleeding a ps system problems. This is something I have never experienced,hydraboost or no.
The
common denominator here at CK5 seems to PCS gear boxes.

Return lines need to run from hydro to gear box, then droop below box and come up to ps reservoir. Return inlet needs to be below the low fluid level in reservoir.

 

[JoshHefnerX]

At the diesel shop we would use a 12” ish radiator hose to extend the filler neck on the pumps and let the aeration run to the top without spilling over so we didn’t lose fluid. Light pressure on the brake pedal while full sweep left to right as per usual. Just letting the bubbles reach the top of the reservoir without getting recirculated was the trick.

I ordered a vacuum cap, but it wont be here for a week.. Was thinking it'd help w/ clearing out any collected aeration.

I kept looking at my radiator bleeding funnel thing thinking - it's not all that different but finding the fittings to make that happen.. Rad hose is pretty simple.. I may dig around to see if I have any that may fit. Wasn't expecting this to be a butthole, when I changed the hydroboost out it bled no problem.

 

[JoshHefnerX]

@obijuank5 Thanks for the tip on that hose.

After 3 days of f'n with it it's finally bled.
Didn't have any rad hose but was able to get ahold of some clear/vinyl or pvc stuff. Did the same job, and got it bled out. Good tip! That and holding the brake at half-staff seemed to clear it up.

I think I was fighting some initial aeration - and even though I'd let it sit between rounds, it probably wasn't long enough to get all of the micro bubbles out so I was reinjecting air into the system on a micro scale and it would coagulate into bigger air. Which would foam up and I couldn't get a good bleed w/o an exxon-valdez down the driveway - that the hose helped resolve.

 

[JoshHefnerX]

common denominator here at CK5 seems to PCS gear boxes.

I was thinking about it - not sure what other people have had, but this replacement for my f350 was a fair bit larger than the factory one. weighed about double, and actually moved the pivot point of the steer arm about 1/2 in. I'm assuming the piston volume inside is larger - and could contribute to bleeding problems...

 

[Blue85]

If you push the tires side to side manually, that works better than using the steering wheel. Once the pump foams you have air in the steering and the brakes. Anything you can do before the pump ever runs helps. I've also heard you can drain the foam out of the reservoir and replace with clean fluid to speed things up, but I've never tried that approach.

 

[Truckman4life]

I did that same conversion way back on a company super duty with a 7.3L. I think it was AGR that sold a kit at that time. It was also terrible to bleed out. Had to go through way too many cycles of starting and turning lock to lock then shutting off and pump down the accumulator then starting up and going lock to lock slowly. I remember calling them even for help cuz it was kicking my ass. The problem is the air gets trapped in the accumulator. The tech guy told me to absolutely never touch the brakes with it running or you gotta start all over. Still had trouble even without doing that.

 

[Wes Harden]

Think I have posted this before.

How I do power steering fill.
I finish the hydraulic system 1st. Completely sealed. Fill reservoir, spin pump by hand a few times, top of. As I am finishing install of remaining, I'll spin pump by hand and top off a few more times. Last item on is belt.
Most times I will disable spark or fuel, and crank the engine a few revolutions, top off, till no longer takes fluid.
Next allow engine to start, and shut down, top off, till no longer takes fluid.
Start and run 5 -10 mins, shut down check fluid level top off.
Then I start and rock the wheel just a little listening for whining. If any it normally stops in just a few seconds.

You can tell I am no longer a flat rate wrench, I can spend as much time priming the hydraulic system as book time says for whole job

 

[imiceman44]

Think I have posted this before.

How I do power steering fill.
I finish the hydraulic system 1st. Completely sealed. Fill reservoir, spin pump by hand a few times, top of. As I am finishing install of remaining, I'll spin pump by hand and top off a few more times. Last item on is belt.
Most times I will disable spark or fuel, and crank the engine a few revolutions, top off, till no longer takes fluid.
Next allow engine to start, and shut down, top off, till no longer takes fluid.
Start and run 5 -10 mins, shut down check fluid level top off.
Then I start and rock the wheel just a little listening for whining. If any it normally stops in just a few seconds.

You can tell I am no longer a flat rate wrench, I can spend as much time priming the hydraulic system as book time says for whole job

That is how I do all my work.
I am fast but I don't take shortcuts and I usually charge by the hour at reasonable rate and my clients like me for it and recommend me