Hydroboost / Powersteering issue

[GloNDark]

I have been struggling with my Power steering for some time now. Setup is as follows

4x4x2 Blue top box
Wildhorse 4x4 MOAB Hydroboost
Was running a delphi style power steering pump. Have destroyed 4 of those. All had dual return setups.
Bought the Wildhorse 4x4 extreme pump setup with external reservoir.
I have a PSC Hydro assist ram with 1 ton steering
Derail aluminum round fin cooler
38x13.50r17 Nitto Trail Grapplers

Install was uneventful, everything went on with out an major problems. Filled it with fluid, turned the wheel 50 or 60 times. Was still getting tiny bubbles here and there. Let it sit on jackstands overnight. Turned the wheel back and forth another 50 times or so. Felt confident that almost all the air was out. Fired it up, turned it back and forth and started hitting the brakes. Some tiny bubbles so I kept turning and hitting the brakes until there was nothing.

Took it off the jackstands, and tested it. Would turn the tires at 12psi with zero issues. Pulled it out of the shop and continued testing in dirt out back and all seemed good. Took it for a test drive the following day on some dirt roads out on blm land. Seemed great for a bit and then it just started puking fluid out of the relief line in the reservoir. Headed back home with the pump starting to whine. Parked it, let it cool. Still has fluid in the reservoir, i'd say about 1/2 full. But pump is whining and now no assisted steering at all.

Truck never got hot. It was probably 45 degrees out. Temp was holding steady at 175 to 178 on the coolant.

 

[toddz69]

The line routing looks correct.

The only thing I see that raises a question in my mind is the double 90 deg. fittings on the pressure in/out on the hydroboost. Probably not an issue but then again, you are on the upper end of the use case spectrum with your tire size and the ram steering.

My $0.02,
Todd Z.

 

[ntsqd]

I questioned the 90's into a banjo fitting as well.

What brand of fluid are you using? My FSB's H-B system with a Sag P-pump and remote reservoir didn't whine with AC-Delco PSF (19329448) in it. It has a leak in the box and when I unthinkingly topped it off with some generic PSF I now have a small whine at times.

 

[GloNDark]

I could definitely get away with a straight fitting on the top of the HB. The pressure line to the box would be tight but looks doable. No way I could get away with a straight fitting on the pressure line at the box. But maybe a 45 to flow better.

Currently have Lucas power steering fluid in it. But willing to try something else for sure.

 

[Bruners4]

I've used a Power Steering Evacuator and my air compressor powered vacuum pump to apply a negative pressure on the standing fluid to help remove any trapped air while bleeding the system. This has helped prevent the aeration that can lead to cavitation and pump damage.

 

[ntsqd]

I *think* it was the PS thread on Irate where I picked up using the AC-Delco PSF as being the fluid preferred by most performance PS rebuilders (who don't sell their own house branded PSF anyway). I'd try changing the fluid first.

I recently bought one of these: Cooling System Vacuum Tester/Filler and just now reading Bruner4's post it struck me that it can likely be used on the PS system too.

 

[Broncobowsher]

I don't like the lack of cooling. That 'cooler' isn't much of a cooler. Fine for a drag racer. Power steering pushing tires with 12PSI in them puts a lot of heat in the fluid and those fins don't really get rid of the heat.

 

[ba123]

Lots of opinions here but I don't think that extra bend is that bad. Certainly not ideal but it's just a bend.

Are you sure those are the correct inlet and outlet on the PS Box?

And PS doesn't need much to cool on normal driving and I'd wait on the doing anything about the cooler. In fact, I have almost the same cooler on mine and it works perfectly. Bowsher might be right that you could need more while wheeling but I'd find the main issue first.

 

[ntsqd]

Tom Lee, the founder of Lee Power Steering and a pioneer in performance power steering systems, was very emphatic to me that only formed tube type 90°'s be used in "his" systems and he'd prefer that only straight hose ends be used if at all possible. No banjo's, no machined 90°s. Both of those cause excessive cavitation. He had the experience to back up that opinion. The H-B's return is probably OK with a banjo fitting in it because the volume flowing thru that is pretty small, but on the high pressure side all of the volume for everything is flowing through them and that's not good.
Grady Hillhouse does a nice job of making things easy to see in this video:

In particular note just how badly the 4 sharp 90's increase the pressure drop and reduce the flow.

Mr. Bowsher has a very valid point. Turning 38x13.50's at 12 psi is going to make some heat, even when just on pavement. That cooler is maybe equal to a long steel tube type OEM PS cooler at best. I agree that it's likely a lower level concern, but it does need to be addressed. That is, unless the whine increases with operating temperature. If it's absent when cold and gradually increases as the PS fluid temp increases as the engine warms up then it's a top level concern and needs to be changed out soon.

I've yet to be impressed with anything from Lucas. My first steps would be to flush the system, eliminate the banjo fittings, and fill it with AC-Delco PSF. If the whine is temperature connected then I'd replace the cooler while I have it all opened up. I tend to use OEM stacked plate aux trans coolers for PSF coolers. Given the ram, I'd go for the larger end of that spectrum.

 

[Yeller]

banjo fittings are terrible heat producers in hydraulics; the turbulence they make is terrible. I have seen them create cavitation, even in a fully bled system once RPM and demand come into play. Puking out the vent tells me it is cavitating and introducing air somewhere or boiling the fluid. I have found the cooler choice to be fine for steering as long as it has adequate air flow.

I personally have a system that struggles on flow, I know it is the 4 swivel 90 fittings in the system, but I have not found an alternative that physically fits, but it never makes excessive heat and runs the same cooler you are but it is out in the wide open with lots of air flow.

 

[jamesroney]

Lots of opinions here but I don't think that extra bend is that bad. Certainly not ideal but it's just a bend.

Are you sure those are the correct inlet and outlet on the PS Box?

And PS doesn't need much to cool on normal driving and I'd wait on the doing anything about the cooler. In fact, I have almost the same cooler on mine and it works perfectly. Bowsher might be right that you could need more while wheeling but I'd find the main issue first.

You are mostly right. (which means everyone else is mostly "not right.") His connections are correct...or else it wouldn't power steer.

The video on head loss is correct, and accurate but difficult to apply here. But the losses were exaggerated by displaying the delta P in inches of water, and the head in pounds per inch squared. If you keep in mind that one psi equals 27.7 inches of H2O, then it works. But the effect would be 27x lower, and difficult to visualize. So I don't blame the author of the video. He was making a point which I will emphasize here. In designing hydraulics, the use of traditional Civil Engineering tools can be used. But the nomenclature of "minor losses" might be incorrect as applied to non-Civil Engineering cases. Which is really important in this application. Because the velocities in the hoses get very big vs the flow. So it should never be called the "minor loss" in a power steering system. I'm not going to re-type the equations here. But the interpretation at 7:06 in the video is compelling. Hazen-Williams losses become overpowered by the kv^2/2g minor losses in the total head loss calculation. So that's nice.

All that is nice, but not interesting. And of course irrelevant as the op @GloNDark has observed. HIS problem has absolutely nothing to do with pressure loss due to head loss. (but thanks for playing...)

Consider the absolutely TORTUOUS path of the hydraulic circuit INSIDE the steering box. And the teeny tiny orifices in the steering box control valve. The fluid goes into the box thru a 3/16 orifice, then bends, twists, ports, and wiggles into a spool valve, then goes to a 3 inch piston, and also thru a tapped port to another fitting to a long hose to an external ram. It's all a bunch of Hooey. The Saginaw box is capable of pushing 1400 psi on the pressure side. But it rarely needs to. Once the back pressure in the system is met...the pressure regulator just dumps the fluid right back into the reservoir. This is why the OP is having the symptoms that he is seeing. System is not overheating, temperatures are modest. When not steering, everything works fine. Hydroboost has plenty of pressure. Small steering inputs have "good" assist. The problem is the ram assist cylinder, and fluid VOLUME. IDK what size the ram piston is, but I'll bet its 1.5 inch or larger. And I will tell you this:

A Saginaw steering pump will cavitate on the input side of the pump if you use a saginaw box, and a 1.5 ram, and you don't manage the suction side of the pump. It is ALL about the suction side. Gravity is NOT your friend. It's not a pressure thing. It's a volume/flow problem, and if you starve the input of the pump. Pump cavitates, and horrible things happen. Then it pukes fluid out the vent. That PSC style reservoir is not doing you any favors.

You've got 1400 psi pushing fluid thru all kinds of banjo fittings, bends, hoses, etc. But you have 14 psi (atmosphere) pushing the fluid back into the pump. That's the problem.

 

[GloNDark]

Ordered up some AC Delco from Summit last night, should be here today.

Should be worth mentioning that even though I have been eating up canned ham pumps, when it does work, it flat out works. It will push itself away from the wall if I turn into it.

Decided to flush the system this morning. Pulled the cooler to res hose and put it in a clear jug and turned the wheel lock to lock. Kept filling the system with some power steering fluid from tractor supply. Everything that came out is a gray metallic slurry. I think I might have a bad pump right out of the box.

 

[ntsqd]

The point of the video link was to show that seemingly innocent parts (sharp 90's like banjo fittings) have large impacts on flow restriction and induce cavitation. If you watch closely you can see the cavitation bubbles in some of those 90's. It wasn't meant to be a PS plumbing how-to.

A point that I'd missed on the first two passes thru the OP's post is that the PS reservoir is vented to atmosphere, something that Jame's post brought to light for me. Yeah, don't do that. I learned that one the hard way. Plug that vent. Long term it'll want a 10-15 psi check valve there, but for short term plug it and try it again. That will pressurize the reservoir from just the thermal expansion of the fluid and put more hydro-static head on the pump. Even just a couple psi can do wonders. BT, DT. Somewhere in the last several pages of the FSB link in my sig I show the reservoir that I built that didn't work. It is vented to atmosphere. The Lee reservoir that replaced it is not. Just changing the reservoir eliminated the whine. I'm working (slowly) on a second gen of my reservoir with a 15 psi check valve in the vent.

 

[Yeller]

@jamesroney Thanks for making me think on this harder. yup vent to atmosphere is a problem along with the height of the reservoir. I detest PSC's reservoir on a bronco, it is almost impossible to get it mounted high enough to not be a problem. For non race applications I prefer the ol tried and true canned ham pump/reservoir if a little more volume is needed due to additional hydraulic imbalance with large boxes and rams, it is easy enough to do. I find it interesting that you "smoked" a couple of Delphi pumps.

 

[GloNDark]

@jamesroney Thanks for making me think on this harder. yup vent to atmosphere is a problem along with the height of the reservoir. I detest PSC's reservoir on a bronco, it is almost impossible to get it mounted high enough to not be a problem. For non race applications I prefer the ol tried and true canned ham pump/reservoir if a little more volume is needed due to additional hydraulic imbalance with large boxes and rams, it is easy enough to do. I find it interesting that you "smoked" a couple of Delphi pumps.

I'd say the first one was due to crappy fluid. Everyone I talked to said the Napa power steering fluid was the problem. The others, I tried a PSC pump that was "higher" volume but didn't seem that high. I have sent both of those off to be rebuilt and hopefully see if they can tell me what the issue is/was.

 

[ba123]

I don't think it's right for a Saginaw, but I LOVE my overpriced Lee's Explorer reservoir. If I ever need to upgrade my pump, I will use their overpriced one as well.

Res is sealed.

 

[ba123]

I'd say the first one was due to crappy fluid. Everyone I talked to said the Napa power steering fluid was the problem. The others, I tried a PSC pump that was "higher" volume but didn't seem that high. I have sent both of those off to be rebuilt and hopefully see if they can tell me what the issue is/was.

Our PS systems call for Type F, although that might just be the stock Bronco but that's what I'm using.

https://www.amsoil.com/p/amsoil-super-shift-racing-transmission-fluid-art/?code=ARTQT-EA

 

[GloNDark]

The point of the video link was to show that seemingly innocent parts (sharp 90's like banjo fittings) have large impacts on flow restriction and induce cavitation. If you watch closely you can see the cavitation bubbles in some of those 90's. It wasn't meant to be a PS plumbing how-to.

A point that I'd missed on the first two passes thru the OP's post is that the PS reservoir is vented to atmosphere, something that Jame's post brought to light for me. Yeah, don't do that. I learned that one the hard way. Plug that vent. Long term it'll want a 10-15 psi check valve there, but for short term plug it and try it again. That will pressurize the reservoir from just the thermal expansion of the fluid and put more hydro-static head on the pump. Even just a couple psi can do wonders. BT, DT. Somewhere in the last several pages of the FSB link in my sig I show the reservoir that I built that didn't work. It is vented to atmosphere. The Lee reservoir that replaced it is not. Just changing the reservoir eliminated the whine. I'm working (slowly) on a second gen of my reservoir with a 15 psi check valve in the vent.

Great point on the vent. I'm going to flush the whole system one more time and make sure there is clean fluid everywhere (Or atleast as much as I can) and plug that vent. Then bleed it all over again and test.

Thanks guys!

Also researching and planning how to get rid of the banjo's and as many bends as I can on the pressure side of things.

 

[ntsqd]

Our PS systems call for Type F, although that might just be the stock Bronco but that's what I'm using.

https://www.amsoil.com/p/amsoil-super-shift-racing-transmission-fluid-art/?code=ARTQT-EA

Once you move away from the atrocious OEM Ford pump I don't think that applies any more. When asked I was told that AC-Delco PSF (that I was already using) was an acceptable alternative to their house branded stuff.
I would also consider Swepco 715, but that's not always easy to find or inexpensive.

 

[ba123]

Well and interestingly, with Lees custom pump they want you to use their fluid. I asked and they said not to use ATF cause it tends to cavitate more but not the synthetic. I know this one I’m using is supposed to not.