Saginaw PS pump vacuum bleeding

Oct 16, 2010
Late 80's mopar.
I replaced my crappy super loose reman'd Steering gear with a Redhead Steering Gear, eating the core charge. $$$!

Lucas PS stop leak had been inside my otherwise problem free quiet PS pump, for years.
Very effective, for years, no leaks, and I'd even forgotten the pump once leaked and stop leak was in there, but did remember and I wanted only clean new pristine PSF in the new redhead gear.
Factory service manual says NO ATF, only PSF!!
Redhead came with Pink ATF inside it, no idea how much of its total volume but I used close to 4 pints to achieve full cold on initial fillup of dry system.

Reading here about so many noisy junky reman'd pumps, I got a Saginaw resealing kit. New pressure and return lines, new Metal body Magnefine filter, fuel injection hose clamps, 4 pints Prestone PSF, Gates V belt.

After all was buttoned back up, I bled the system, wheels off the ground slow lock to lock 20 times engine off, all was well. Level when cold next day, was at the full cold line on dipstick
Drove 50 miles, highway, around town, parallel parking....multiple lock to locks, no leaks. All was well. Steering so much tighter, very happy with results.

Started driving cross country. ~150 miles into ~2500 mile drive, had to tighten new Gates V belt, as expected. 15mm socket and wrenches and tarp to lay on, ready to go.
Pump/reservoir exterior body and hoses still dry, did not check PS fluid level.
~1500 miles later, 11Pm ish, pulling off highway to get gas, only half or less of power assist.

Fill tank, open hood, Dipstick dry, reservoir body wet on bottom. OK. Better there be an obvious reason for half the expected power assist.

Sketchy gas station, unmasked undesirables harassing me for money, others eyeballing me from edge of parking lot, while hood was up, and my goofy unthreatening dog going uncharacteristically nuts on front seat. Hairs raised on back on neck, really bad vibes as all other cars at the pumps depart.

Unintentionally Overfilled reservoir with Lucas PS stop leak, and got out of there, back on highway, late at night. Overfilled PS pump reservoir, and full tank of gas
Power assist had returned, all felt normal, pump did not make any noise, did not get robbed, Phew!

Kept driving, no turkey baster to suck out excess PSF in safe well lit area It was on my list, still forgotten. curses!
Steering felt normal, Pump still quiet, but no lock to lock movements, even when getting fuel or at rest stops, straight highway driving. Kept going, with reservoir overfilled.

Pump body Dry at next gas station fillup. Still well overfilled. Wherever leak was, it appeared to have stopped.
Kept going.
~1000 miles after unintentional overfill arrival at destination, did first lock to lock movement of wheel, twice, When parking high and tight, out of the way.
Power assist felt lacking nearing full lock, and PS pump noise occurred only with the wheels nearly fully turned, not very loud though, not like a early 90s ford ranger.
Raised eyebrows but shut off engine. Done. ~2500 miles in less than 4 days.

2 hours later unloading, Noticed PS fluid burped out reservoir cap onto driveway after I shut off engine when parked. No drips elsewhere on driveway from maneuvering.

Wiped everything dry. Pump and reservoir body, lines nearest pump, centerlink, drag link, pavers.

Vehicle sat for week+ untouched. Pump body dry, no drips anywhere, not on lines, not on filter, not on gear, none on pavers, not on center or drag links.

Acquired turkey baster, sucked cold out fluid to 'full cold' level, squeezed turkey baster contents back into original Lucas bottle. Bottle Was returned to nearly the level it was when I opened it 1000 miles earlier! must be tons of air in system i think. Turned vehicle around 180 degrees, parking higher and tighter. lots of maneuvering, lock to lock. Later noticed reservoir had burped again on driveway, after engine shutdown, and wiped up all drips everywhere. Not as much, but still.

Bought brake vaccuum bleeder at HF, formed seal on top of pump with parts I found in garage to rebuild toilet internals.
Lifted front tires, 15 PSi vacuum applied, lock to lock engine off. Maintained 15PSI with no further pumping of hand vaccuum pump. No leaks, no loss of vacuum. Slow lock to lock movements, 20, not slamming against locks, gentle.

Check level expecting to have to add more. Just barely below full cold. Add more to precisely full cold. reapply 15 psi vacuum.
lather rinse repeat. Lock to lock slowly. check level
Slightly below full cold mark on dipstick.
no bubbles on dipstick. repeat. repeat, same. repeat, same.

Start engine, run to full temperature, idle till pump body almost hurts from heat, holding it for 15 seconds, 155f via IR temp gun. 16PSi on vaccuum gauge holding steady. Running engine increases vaccum from 15 to 16psi, returns to 15 shutting engine off.
turn off engine, check level, 1/2" above full cold on dipstick 1 inch below full hot, no bubbles clinging to dipstick.

restart engine, lock to lock, not slamming against locks or holding it at locks. Dozen plus times with 16psi vacuum, but Lucas bottle is still close to full and most of the loss can be attributed to what burped out reservoir cap on driveway on arrival at destination. Got to be air in there!

So the Dipstick appeared dry 1000 miles earlier, at that point I opened a new bottle of PS stopleak, and unintentionally overfilled reservoir. and drove overfilled for 1K more miles with no issues.
Burped ~3 tablespoons on driveway at first full lock to lock movement on arrival, but pump apparently quit leaking enroute with the PS stop leak added, too much added.
Sucked out the excess stopleak, returned fluid to the bottle, bled and vacuum bled, and bottle nearly as full as when I opened it perhaps 4 or 5 tablespoons from full as I recall the full level being when i removed the foil seal. Inexact estimations.

I walked away. Have not driven it yet.

I am perplexed why more fluid is not required to reach full cold, or when hot, the full hot mark after vacuum bleeding.
No noise from pump, no notchy feeling through out range, feels like full assist throughout full range, while wheels still off ground.

Did I really pull into that Sketchy gas station low only one tablespoon of PSF? Seems highly unlikely, possible, but unlikely.

If there was still a lot of entrapped air, It would make sense, but there does not appear to be any indicators there is any trapped air within. Yet, anyway. I can't easily see into reservoir, and there does not appear to be bubbles on dipstick when I pull it out to check the level. Clear vacuum tubing end not submerged inside pump, and am not using inline reservoir. so no indication of bubbles there, no ps pump noise, full power assist through full range.

Only thing I can think of:

I do have the new metal can magnefine filter inline, horizontally, on the return line. The return hose I left a bit long and zip tied it upwards , before going down to the return receptacle on pump body. but I cut these zip ties off today and moved return line so it was all downhill to the pump return inlet.
I wonder if this inline filter, is only half full. It is a pretty big filter. and its interior volume is not insignificant.

I wonder if I left with that filter only half full and was perhaps well below the full cold mark or full hot mark on the dipstick but purged the air from the filter once driving at 2K rpm for hours on end.
I just looked for drips after stopping to rest and fillups. I saw no drips and kept going, did not pull the PS dipstick.

perhaps that filter is only half full now, and explains why it took so little PSF to reach the full cold level AND well short of full hot, when hot.

perhaps tomorrow when i check it , after the bleeding and potentially all the microbubbles dissipate, it will read well below full cold, which would be a dry dipstick.

I've read so many different contradicting procedures on PS pump bleeding, I am going cross eyed. My FSM is disturbingly absent of info of this procedure for this vehicle.

Perhaps 15PSi vacuum is too timid.

I am a bit reluctant to blow whatever Oring had started leaking enroute, and was stopped by the Lucas PS stop leak, by pumping to higher than 15psi.
The Fluid now seems only slightly thicker than it was before the Lucas, which was darned thick out of the bottle @ 55f bottle temp or so, taking forever to flow down Tx funnel 1000 miles earlier, and which was a factor in the overfilling, but not as much as the hairs standing up on the back of my neck while feeling like there was a bullseye on my shirt.
That Lucas is thick stuff. I talked my dad out of pouring it in the power steering system on his truck to stop a seal leaking I am just going to replace the seal for him instead. I hope you get your issue sorted out.
I have 6 PS pumps on the bench for my gmt400, I finally refilled with Honda spec fluid which I had been using previously- don't remember why I changed it out....and after Lucas, Redline, RP-- went back to it. Don't know the whats or whys, but it just works in my HB system.
I've not driven the vehicle again other than to reposition it again higher and tighter in driveway, and no more drips, no noise, no notchy assist.
Hoping the issue is sorted.

The capacity of the steering gear itself is 2.5 pints, the pump is another 1.5 or so, the 3/4 pint I added of Lucas PS stop leak, should not really have thickened the total volumn to a ridiculous degree.
I'd have preferred to not have had to use it, but Oh well, glad I had it on hand when I found it low.