Ranger Hydro Assist - Which Pump

[Bray D]

I started this thread on PBB and it turned into a collegiate level fluid study. It needs documented here.

In typical repost fashion, I'll condense the original thread down to 5 posts to keep it fairly concise. Even so, this is going to be a massive data dump. This is going to take a while, so feel free to refer to the original thread if necessary: Ranger Hydro Assist - Which Pump

Here's the post that started the original thread to kick things off:

I've been researching hydro assist systems and I'm to the point where I'm ready to pull the trigger. I plan to run a Saginaw P pump with an external reservoir, which will feed my stock gear box and a 1.5" x 8" PSC cylinder.

There's a handful of different Sag pumps pending the OEM vehicle application. I want to make sure I get the one that has the appropriate pressure and flow rate. See the charts below from the Billavista Tech article:

More pressure and flow is typically better, but I don't want to over pressurize my stock gearbox. I haven't found any numbers to show what my stock pressure and flow is.

Does anyone know the output numbers for my stock (4.0L OHV) pump? Has anyone blown the seals out of their stock gear box from an over-performing pump?

 

[Bray D]

The general consensus was that the box can handle pretty much any pump you put behind it. The goal is now to find the pump with the highest pressure and flow to maximize steering power and speed.

Newstar number S-A386 looks to be the ticket for a new pump. Unfortunately, I couldn't find any place that sold it. Discussion of a high performance PSC pump came up, but I ultimately made the decision to stick with OEM stuff. Cost, availability, etc etc.

DMANbluesfreak says:

So, I did some research on this before I pulled the trigger on my pump after my first pump bit the dust. From what I understand, any Hydroboost pump for a GM application with a steering box (not rack & pinion) after the 2000s (ish) has even higher pressure output. GM 20832683, for example, is from a 2009+ 1 ton Express Van w/ Hydroboost and puts out 1425psi to 1525psi (verified to the GM print that I have at work). It also meets the same flow as the other pumps you posted and has a remote reservoir can on it (similar to the PSC can, but with a barb fitting instead of the -AN fitting). This one is $168 on rockauto after core.

GM 20756715 is what I ultimately ended up purchasing. It is from a 2006 Silverado 2500HD 6.0L truck w/ Hydroboost. It does not have the reservoir can you're looking for but it is brand new, not remanufactured. It's approximately $130 and you'd have to buy a separate can from PSC or something to make it fit in your application (I think). Still, you're under $200 for the whole setup and it's a brand new pump. The research I did at the time put this between 1500-1600psi, but I'm now starting to doubt the numbers are that high, so I think they match the Express van output numbers.

Bray:

I planned to run a remote reservoir so discussion was had about remote reservoir cans and where the return line should go - either to the can on the pump or to the reservoir itself. Concerns for pump cavitation came up, but we landed on it likely being OK since there are millions of vehicles on the road running remote res setups.

I ended up ordering the GM pump per DMAN's recommendation, PSC remote res with filter, horseshoe bracket to bolt the pump to my OEM bracket, pulley, and a small cooler.

Pump: ACDelco GM 20756715
Can: PSC-SR2545-12K
Filter Reservoir: PSC-SR146-8-12
Bracket: PSC-MB03K
Pulley: PSC-PP2450
Cooler: Derale 13212

Found some info regarding this GM pump. Looks like this guy works for Napa and called their distributor direct to get the pump specs:

Found interesting P/S pump info!

Excerpts from his thread:

I looked to the GM Vortec 6.0L with hydroboost.

Hose Port Type : Tube Fitting
P/S Pump Line Thread Size : M16 x 1.5
P/S Pump Shaft Type : w/ Hub, Internal Thread

This pump is rated to produce 1280-1550psi and puts out 1.7GPM at 400rpm and 3.6GPM at 1600rpm.

Josh40601:

Some bitchin tech in here about pumps. Since Bray and I have slightly different setups on our vehicles, but they are both RBV, I asked him if I could throw my info on here for those who are running the older 4.0 bracket. This is the bracket that has a full circle where you have to pull the pulley to remove the pump. Bray has the newer style that has the cut out at the bottom. THERE IS A DIFFERENCE Although it is a small difference, it will make a difference when mounting the pump setup.

Older OHV 4.0 (91-94 style) on the left - Bracket thickness at mounting is 8MM
Newer OHV 4.0 (95-97) on the right - Bracket thickness is 11MM

Bray:

My parts arrived so I started with the pump swap.

More grinding was necessary to open it up around the -12 inlet on the top, but you get the idea.

OEM Ranger pump to pulley measurement. The stackup showed that the new pulley would have to be cantilevered off of the P pump shaft ~1/8". That proved to be true. It's been running like that without issue.

Got everything mocked up in the rig and found that my belt was too short. Had to bypass the tensioner to get it loosely on there. This is a '97 4.0 OHV with no A/C for reference.

My old belt was 6K810. Typical belt for my engine without AC.

RockAuto says the length is 81.608". 6K870 is the number with AC - 87.592" length. Simply numbers for reference. Tried a couple different belts and 6K820 was the winner. 81.96" long according to Rock Auto.

Next up was determining the reservoir location. I mocked it up between the brake master and engine, tried another location over on the driver inner fender, and ultimately landed on mounting it off of the rad support up front. Unfortunately, I had to do some work to keep the reservoir under the hood.

The PSC res is damn near 9" to the top of the fitting.

I chucked it up in the lathe, turned it down, and welded it back up. I also replaced the PSC elbow with a home brew 'anti splash' setup. One fitting is a bypass valve that will let air in at 0.3psi vacuum and the other is a pressure relief at 7.5psi. I figured a little system pressure would be a good thing once it warmed up, and 0.3psi vacuum shouldn't hurt anything. It stays fairly dry, but does weep from time to time. It's not bad enough that I want to change anything.

Those fittings got machined down to minimize height as well.

McMaster-Carr part numbers
0.3psi Relief: 1093K2
7.5psi Bypass: 7775K41

With this res height, the output is above the pump and everything is still under-hood.

Res mounting bracket

PS cooler mounted to the front of the radiator

-6 braided stainless pressure line. Barbed and clamped return line.

-12 feed line

I got this install wrapped up and headed to CO / Moab for a week of mountain passes and hardcore wheeling.

 

[Bray D]

Made it to CO with no issues. Ran a handful of mountain passes around Ouray just fine, though I can't even remember if I engaged 4wd. Scenic, but pretty light duty 'wheeling'. Made our way to Moab and that's when the fun started.

I blew the seal out of the steering box halfway through Hell's Revenge. Tried to just plug the pump output and let it run in relief, but it overheated almost instantly. Ended up bypassing the box and routing the fluid through the cooler back to the res to just let it circulate. Unlocked the hubs and ran the rest of the trail in 2wd without power steering.

This was a fresh reman box that I installed while I did the pump swap. O'reilly honored the warranty and was able to have another box ready for me the following morning. Did that swap in their parking lot and all was well.

On the last day of the trip we ran PSM in the heat of the day. Locked up the steering multiple times on downhill features, etc. Everything held together just fine. I chalk the box failure up to a poor rebuild. No issues since. Drove 1200 miles home without skipping a beat (though the pump was howling like Chewy at this point from all of the aeration / overheating).

I checked fluid temp at the end of the last trail and saw 170°+F at the reservoir. After the overheating issue (due to my dumbass) and the relatively high temps in the res, I decided I wanted real time temp monitoring. I had a spare port on the reservoir to use for a sender and space in my dash for a gauge, so it all fell into place really well. I ended up ordering a new pump, gauge, and cooler.

Link to gauge: 2-1/16

The new cooler is slightly larger that the old one. It has the same number of passes, but it's twice as long and has JIC fittings.

Derale 13311 - 4 Pass 13'' Series 7000 Copper/Aluminum Transmission Cooler, -6AN

Some tech regarding the gauges - I have them wired to ignition power so they're on all of the time and not dimmable. I wanted them clear and bright at night, but not so bright that they're distracting. This is what I landed on and it's perfect.

Air core PS fluid temp, mechanical engine oil pressure, air core coolant temp. I tried a few different light combos to see what I liked and ended up getting these 30 lumen LEDS in 6k color temp.

Part number: 194-x5-LAN - 194 LED Landscape Light Bulb - 5 LED - Miniature Wedge Retrofit - 30 Lumens | Super Bright LEDs

At this point it was the dead of winter and I started having cavitation issues at startup. This is what kicked off the fluid investigation.

 

[Bray D]

3/5

 

[Bray D]

4/5

 

[Bray D]

5/5

 

[gump1376]

This is interesting. It looks like the pump bracket is very similar to that used for the saginaw pump on the 351W. I'm also probably gonna need to upgrade my pump at some point as I'm looking at adding hydroboost along with my hydro assist steering. Thanks for the info.