H3 I5 power steering pump comparison.

[rascole]

Since my SAS I recently started to have power steering pump whine after an hour of wheeling. On the street and highway everything is quite but as soon as there is constant demand on the trail, the howling starts. Clearly the FJ80 box and PSC ram assist are too much and the fluid is getting hot. I installed this current pump in 2019 so it is relatively new and few miles. I’ve been chatting with someone from Radial Dynamics and first thing he said was get the biggest cooler and think about an aftermarket pump. So it got me thinking. Because the H3 PS pumps and reservoirs are getting scarce, I thunk outside the box. With the H3 being a close cousin to the Colorado and Trailblazer, I decided to do a side by side comparison. I bought a Cardone reman for a 2006 H3, Colie and 4.2l TB. The H3 pump is very similar in construction but differs In a few ways.

• Rear assembly for the Colie & Trailblazer use a snap ring to hold together, H3 is a bolted body for higher PSI I presume.
• Pump cavity on both is notably smaller so GPM is clearly lower, PSI might be the same though. TB is slightly larger than the Colorado.
• All the pump castings share the same 3 bolt mounting but each housing is slightly different. All 3 bolted up to the H3 with no interference.
• Pump vanes are smaller most likely due to lower flow and pressure demand.
• Pump shaft is larger on the Colie and TB so a H3 pulley will not work.
• Reservoir is slightly larger on the Colie and huge for the TB, H3 inadequacies are real.
• All the reservoirs’ mounts are different so they are not interchangeable with each other.

Over all the Colorado/Trailblazer complete assembly will work if you are desperate and might even last on a street driven H3.

From left to right. H3-----Colorado-----Trailblazer

 

[rascole]

Colorado pump vanes. Smallest of the bunch.

 

[rascole]

Trailblazer pump vanes, slightly larger.

 

[rascole]

H3 pump vanes.

 

[rascole]

Colorado pump installed.

 

[rascole]

TB pump installed. Tight but it clears.

 

[rascole]

Colorado vs H3 pump.

 

[alrock]

Geek!

Awesome comparison. You are correct with the H3 power steering components. The AC Delco pumps are nowhere to be found. All of the other pump sales are without reservoir or pulley. The pulley is not available anywhere. Do NOT lose or damage that pulley if you are replacing your PS pump.

 

[cgalpha08]

Randy,

I have also noticed the hot fluid, like so hot the pump will burn you within a half second hot. I installed a pass through heat sink cooler and that seems to help to a certain degree.
Since i have the v8 i can run other accessory brackets made for LS motors and have a bracket sitting the the garage that will run let me install a PSC pump and a remote reservoir, and thus a massive cooler up front.

Have you given any thought to trying to run something similar on the i5? it shouldn't be too terribly difficult to get a bracket made up that has the spacing right to let you run a psc or some other aftermarket pump. More pressure, remote reservoir, big a$$ cooler.

 

[rascole]

Randy,

I have also noticed the hot fluid, like so hot the pump will burn you within a half second hot. I installed a pass through heat sink cooler and that seems to help to a certain degree.
Since i have the v8 i can run other accessory brackets made for LS motors and have a bracket sitting the the garage that will run let me install a PSC pump and a remote reservoir, and thus a massive cooler up front.

Have you given any thought to trying to run something similar on the i5? it shouldn't be too terribly difficult to get a bracket made up that has the spacing right to let you run a psc or some other aftermarket pump. More pressure, remote reservoir, big a$$ cooler.

Yes, working on that this week. I will add pics when I am done. I am adding a 18" finned aluminum cooler. It will add 24 ounces of fluid, which is a lot for the I5 and it will be mounted on the new cross member Steve made for the front of the frame behind the radiator. Perfect spot.

 

[06 H3]

GREAT INFO.

I have gone down the rabbit hole for fluid volume for a “special” project I am working on. This is very helpful.

From the back of it it looks like the H3 pump can push more volume per revolution?

 

[EndeavoredH3]

I see Chris brought back this thread, and it resurrected some past thoughts.

Wonder why a ls pump hasn't been retrofitted with a remote reservoir yet. Along with a 1 ton steering rack. And long travel suspension, and a 1 ton ifs front diff... That got expensive quick.

But for what its worth. It appears an LS pump and the h3 pump have a similar housing, just flipped. Would be curious to see if internals would swap over if the veins were beefier.

I need to get out of this townhome and into a house with a garage.

 

[06 H3]

I ordered one, I’ll be tearing it apart and seeing what I can find in the name of Cubic inches per revolution. That’s what I need for low end flow for what I am trying to create.

If anyone has a used H3 pump/dying I’ll buy it off of you so I can tear that apart instead

 

[rascole]

I ordered one, I’ll be tearing it apart and seeing what I can find in the name of Cubic inches per revolution. That’s what I need for low end flow for what I am trying to create.

If anyone has a used H3 pump/dying I’ll buy it off of you so I can tear that apart instead

I have an old Cardone I bought sitting on the bench. Was going to have it rebuilt and modified but with the swap around the corner I won't need it. No res or pully though.

 

[Korby7]

I ordered one, I’ll be tearing it apart and seeing what I can find in the name of Cubic inches per revolution. That’s what I need for low end flow for what I am trying to create.

If anyone has a used H3 pump/dying I’ll buy it off of you so I can tear that apart instead

I have a complete I-5 assembly off my parts vehicle you’re welcome to. I also have a dying/ dead 5.3 pump I’m replacing this week. No pulley for the 5.3 though.

 

[06 H3]

No pulleys or resi needed. Thanks guys! @Korby7 you are in Utah right? I may be in Utah for work in the next 2 weeks.

My thought process is get the cu in per rev, the most important part for my needs. If it’s greater than the average pump I’ll use my new one. I’ll tap the resi port for a large AN hose to run to the PSC pulley (essentially what PSC does on their pumps) drill out the flow piston and remove any shims to up the pressure of the pump.

I have 2 questions, do either of you have the outside diameter pulley size and a pic of the h3 pump without the pulley on it?

I want to see if the h3 pump uses a brass bushing or bearing on the front and I want to see how crazy they get on pulley size for low end flow.

 

[rascole]

No pulleys or resi needed. Thanks guys! @Korby7 you are in Utah right? I may be in Utah for work in the next 2 weeks.

My thought process is get the cu in per rev, the most important part for my needs. If it’s greater than the average pump I’ll use my new one. I’ll tap the resi port for a large AN hose to run to the PSC pulley (essentially what PSC does on their pumps) drill out the flow piston and remove any shims to up the pressure of the pump.

I have 2 questions, do either of you have the outside diameter pulley size and a pic of the h3 pump without the pulley on it?

I want to see if the h3 pump uses a brass bushing or bearing on the front and I want to see how crazy they get on pulley size for low end flow.

I can measure the pulley and send a pic of my spare tonight. If your trip doesn't work out, I can bring it to Sand Hollow next month.

 

[Korby7]

No pulleys or resi needed. Thanks guys! @Korby7 you are in Utah right? I may be in Utah for work in the next 2 weeks.

My thought process is get the cu in per rev, the most important part for my needs. If it’s greater than the average pump I’ll use my new one. I’ll tap the resi port for a large AN hose to run to the PSC pulley (essentially what PSC does on their pumps) drill out the flow piston and remove any shims to up the pressure of the pump.

I have 2 questions, do either of you have the outside diameter pulley size and a pic of the h3 pump without the pulley on it?

I want to see if the h3 pump uses a brass bushing or bearing on the front and I want to see how crazy they get on pulley size for low end flow.

PM sent.

 

[cgalpha08]

I have 2 questions, do either of you have the outside diameter pulley size and a pic of the h3 pump without the pulley on it?

I have a brand new alpha pump sitting on the shelf without a pully they i can take pictures of tonight as well.

 

[06 H3]

Ok, here we go. I may copy and paste this tech into my thread but for now it belongs here.

What I am trying to accomplish is to have a system that has a lot of power and in this case the power comes at the downfall of needing a ton of volume. I can setup a system with moderate volume needs so I can run a regular old pump and move on but that setup is a full hydro setup or a remote servo. I am not a fan of the full hydro idea for what I do. You will find people on the internet who claim their full hydro setup feels great on road at 70 mph but every person I know who has full hydro says it is sketchy on road at speed. I still drive it on road and do not want to deal with full hydro sketchiness. I do believe a system out there works well. Hell, Erik Miller and Randy Slauson have solid axle cars doing 110 in the desert at KOH. I'm sure the setup works and isn't sketchy, but I have yet to find one. The remote servo setup would work, and I will probably end up there some day, but it is pricey so for now, I want to try the 2.5in double ended ram that the full hydro guys use but, in a ram, assist setup.

Before I go into Power steering pump tech I want to backtrack to 2023. Prior to 2023 I had a setup that never seemed to lack power to turn the tires but I felt it was slow and didn't pull enough angle, granted I know my dumb wide 43s were the limit of my turning radius hitting the lower control arms but I still wanted more speed and angle for the day I would end up on narrower tires. I hit the drawing board and laid it out here.

In red was my old setup, early 2023 I moved the knuckle steering arm hole in one hole. This would effectively speed up the steering, and give me more angle, since the box turns the same amount but now the pivot point is closer at the knuckle hence turning more. With that said, the leverage point is now closer which effectively reduces the power. If you are standing on a train not holding on to anything and you take off, if your legs are close to each other, you are more likely to fall over from the force of acceleration then if you have your stance farther apart. It is the same theory here. Now the stance is closer, you have less leverage to work against the force.

So that brings me to today. I now have a system that needs more power.


Power steering pumps are usually looked at via GPM (gallons per minute) and PSI (pressure.) It is RARELY talked about but I think cubic inches of volume per 1 revolution is the most important thing!!! (I will call it cu in./rev going forward) So how much volume of fluid is sent out of the pump when the pump shaft spins ONE time. I think that, especially in my case is the most important part. I will get to WHY soon.

Admittedly, I have a stock pump, they are usually around 1200 psi. I can up the pressure and get more power.

A simple psi increase does increase force from the ram.

but I am still lightyears away from the buggy guys or highly modified jeep guys that run full hydro in terms of power, and yet I am heavier than them, and have bigger tires then most of them! I need more.

I blacked out the push force because single ended rams vary power assist if it is pushing or pulling but double ended rams are pull only. So still 5500 lbs of force 2500-3k.

Now full hydro guys do not have a box help apply force and neither do remote servo guys. So the box does something but it is difficult to find how much. Also, you have to apply math equations to multiply or subtract force depending on pitman arm to steering arm ratios.

Someone I trust and respect said you want the force applied to be the same as your vehicle weight. Now he is doing extreme things, so I think I can get away with a little less, but I am substantially less right now.

Before we start on volume of the pump let's talk about how it works. The pump has a pump cavity. The pump shaft spins. it fills the cavity (see pic below) with fluid. that fluid is sent to the flow control valve (2 pics below) has a tiny hole in it. It restricts how much fluid exits the pump to the box and/or ram. Pic 3 is the pressure regulator if you see the brass shim or washer on it that is what changes the pressure. The taller it is (more shims/washers) the less pressure, the shorter it is (remove all the shims/washers) the higher the pressure.

Here are all 3 components (spring, flow control valve and pressure regulator)

and they go in here.

which is right below the high pressure outlet.

 

[06 H3]

So, all this talk and nothing about the pump. So now let's talk about volume!! The whole reason I started asking questions.

There is a lot going on here. Crank pulley diameter, PS pump pulley diameter (and a 2nd option to compare)
Pump displacement per rev (cu in./rev) the most important part!!!!
flow control regulation. How many gallons is the system being capped at?

lock to lock time is done 2 times. One with the flow control valve completely removed (unlimited flow) and one with the flow control valve in limiting to X amount gpm with a 90% efficiency rate.

So, you can modify anything in green. FYI, this is not my current setup, it is actually someone else's. It is saying with a .8 Cu in/rev pump and a 5.5 pulley you are 3.94 seconds lock to lock at idle assuming no other limitations such as steering box bottle necks with small fluid ports or mechanical limitations or even yourself! Now with a box that is 2 steering wheel (360*) turns lock to lock it probably isn't fast enough but if you have a 4 turn box can you turn the wheel 4 times from lock to lock faster then 3.94 seconds? Maybe not so this flow is a non issue.

So how do you get this better?!? More flow! Which I stupidly thought I will go on PSC, howe, Radial Dynamics, trail gear, etc. and order the pump at 6gpm!!!! That will get me the volume I need. Well I am wrong. I could buy take the a bone stock TC pump at .64 cu in./rev that is limited to 2.6 gpm and then buy a TC pump rated at 6 gpm and it will behave EXACTLY the same at idle. at 600 rpm none of these pumps are pumping 6gpm, they will at higher rpm.

So take a look here, at 3000 rpm all these pumps are putting out 8.3-15.8 gpm. the 6 gpm rating is the hole size that is drilled in the flow control valve. So .64 cu/in rev as an example it is making 8.3 gpm at 3000 rpm. It is allowing 6 gpm through the hole and returning 2.3 gpm back to the resi.

So you can only get more idle flow by going to a smaller pump pulley or a bigger cu in/rev pump. an LS has a 7.5 in crank pulley a 4.5in crank pulley on a PS pump would have you spinning at 10,000 rpm when at a redline of 6000 rpm. that will kill a pump asap.

So that takes us to why I am so intrigued by the H3 pump. Looking at the comparisons to the other pumps rascole posted I think this is a hi displacement (cu in/ rev) pump! It will deliver low end flow better then the other pumps. I need to confirm this and measure the volume it can produce by tearing apart one of these pumps.

Now, why doesnt everyone just go grab a TT P235 pump? 1.22 cu in/rev... Well they did....they were in late 90's C6500 topkicks and trophy truck guys were buying them up for the massive low end displacement that now they are rare so the aftermarket is putting the 1.22 cu in/rev campacks in custom and sometimes billet housings. They are all over $1500 bucks.

 

[06 H3]

TC pumps vs P pumps. I have heard racers say the P in P pump is piece of shit. In their application this makes sense, they have high stall converters, they are running near redline racing. The TC pump flows less at idle but at high rpm it is being limited by the flow control valve anyways and the TC pump has better pump shaft support with bearings, vs a bushing. So the TC Pump is the answer, but for crawlers who dont live at redline and need low end steering speed a p pump may be better. The back of the pump usually leaks and the shaft is supported by a bronze bushing but you get .95 cu in/rev compared to .64 of a TC Pump. That is a benefit.

I also asked if you can start porting the pump cavity to get more flow. Unfortunately you can't without special machinery. I am told the finish on them is smooth and glides well, you also need to make the "legs" that fan out and "scoop" the fluid longer.

So I want to measure this H3 pump and see where it is at for cu in/rev.

A PSC CBR pump is a good example of WTF. The TC cam gears fit in a CBR pump so you can order one and one may be a .64 or one is a .95 cam ring in the cavity. That is ridiculous as it is a 33% change in volume on idle. They essentially take the reservoir port that the plastic resi's go into, tap it for an AN Fitting, put an AN fitting in the high pressure side, drill out the flow control valve for your desired GPM and up the pressure. That's it. I see the CBX race pump you can request the specific cam pack.

Lastly, excessive GPM at high rpm isnt always a good thing, too much GPM at high rpm make the steering twitchy and floaty. So ideally you want massive cu in/rev for low end flow then limit it back with the control valve.

So my current setup does not seem limited mechanically like it once was. It could be faster with a 2.5 turn box but I believe my new restriction is the pump with my current setup so I need to find an even better pump for a more demanding setup.

This is all applicable to a system that is not restricted by other external factors outside of the pump. That is a different conversation for a different day, next time we can talk about remote servos and depowering boxes.

 

[rascole]

Great write up. My thought is there is a thin line for ideal steering. Too much or too little flow or pressure and you will over heat and tear it up. From what I am told, pressure is king, better to have more pressure than flow. For desert racers, they need TONS of flow for massive amounts wheel correction every second. Tires are hardly ever on the ground so there is little resistance, when they are, it is usually soft dirt. Crawlers on the other hand are always fighting side loads or friction with small & slow corrections, here pressure is king. Up size the ram assist and you can move a mountain. For a multipurpose rig like yours, you need a happy balance, even with just 37's, I can feel the pump struggle when I am in a parking lot trying to maneuver around and park. The newer option is electrically assisted steering, would like to see that adapted for off road.

 

[06 H3]

Thanks, I think electronically assisted steering is great and I hope to see a future in it. It was sad to see PSC quickly go to a traditional pump and ram assist setup on the JL platform but then again I am not a PSC fan. I feel they are in the market for selling to the masses with low cost products. Why R&D the JL electronic pump when you can sell more components in a "conversion kit"

The biggest thing about electric steering is low rpm flow. You do not rely on rpm to get flow so you can get it at any rpm.

While I am not sold on EV per say I am excited to see electric power steering and electric e brakes. I want to adapt tesla e brakes on my rear axle. That is starting to become more common on 14 bolt swaps. They have e brake options but they usually suck, the tesla electric e brake applies a shit load of clamping force.