Weak Power Steering Issues

[DieselSlug]

I am trying to get to the bottom of an on-going issue I've had for several years with my 05 Yukon XL. It is mostly pertaining to power steering effort while the vehicle is moving very slow or stationary. Specifically navigating parking spaces, parallel parking, at idle, etc. I have very little if any support from the power steering system and it feels mostly manual until I can get the vehicle rolling at least a couple MPH. This seems worse while on the brakes as well but I do also notice it while off the brakes as the Yukon is equipped with hydroboost.

I replaced the initial steering pump when I got the vehicle about 4 years ago (2022) due to a leaky rotted out reservoir. I purchased a reman Cardone on Rock Auto which was noisy as hell right from the get-go. I ended up replacing the Cardone with a Napa remanufactured (still a POS Cardone I later find out) unit in 2023 which started the hard steering issues. I ran this until April 2025 where I purchased a "new" Edelmann Pump off RockAuto hoping to cure the issues. With this pump since install I have still had issues with the steering at very slow speeds. Contemplating if it it truly pump issues or maybe Hydroboost issues? I have replaced the hydroboost due to leaky seals back in 2022 with another reman (you guessed it, POS Cardone). My brakes seem fine, but could this be causing me an issue? I've also watched some videos of people boosting pressure of the pump to a max of 1,400 psi to help with larger tires. I still have the old Napa unit in a box that I might take apart for inspections

 

[ak diesel driver]

I'm not sure boosting the pressure will help at idle. I'd be looking for a low mileage OEM one in a wrecking yard. For what it's worth mine's similar but not as bad. According to the edelman tech he thinks it's not bled good enough. I would think it would self bleed eventually but it's never changed. Not sure if I believe the tech guy

 

[dbrannon79]

Check the orifice size in the pump. it;s flow not pressure that is the problem. in most cases the OEM pump had the correct orifice size and when it was replaced with the re-manufactured, they tend to us a "one size fits all" for them. I had this issue with my 95 and regrettably returned the core (my factory pump) with the old orifice.

iirc your rig will also have the electronic variable sensor on the back of the pump also. that can be fubar also. but threaded into the back of the pump where the pressure hose attaches is the orifice, behind this is the pressure relief valve and spring. the hole in the center of the fitting that the hose connects to is the orifice. usually it's size it check by fitting the butt end of a drill bit in to it figuring out what size fits best. to get more flow, you simply drill out with the next size bit. there is a limit to how large you can go before you max out the flow the pump is capable of as well as opening up that orifice will also effect it's operating pressures which might require you to pull the valve and reduce the amount of shims in the valve to increase pressure.

on the reman ones the "one size fits all" usually is not intended for the hydro-boost and only accommodates enough pressure and flow for the gear box alone. also the gear box comes into play as well. multiple gear boxes will fit but internal piston sizes can be different depending on the vehicle chassis and GVRW rating. you can usually tell by looking at the end cap of the gear box and see how big the piston is when comparing two boxes. the larger piston gear box will provide easier steering coupled with a pump with larger orifice for flow.

I played this game with my 95 after replacing all the components with reman parts until I got it somewhat right, not perfect, but better.

There is a good writeup online about this in another forum specifically for the GMT400's but a lot of the info will help with yours. I will have to do some searching to find it. iirc it was on the GMT400 forums.

But from what is sound like, the issue is one or the other. a faulty variable EVO sensor on the pump or the orifice in the pump and or gear box piston size. (iirc you did a gear box swap too?)

 

[MrMarty51]

I wonder if a smaller pulley could help boost things up a little.

 

[DieselSlug]

I'm not sure boosting the pressure will help at idle. I'd be looking for a low mileage OEM one in a wrecking yard. For what it's worth mine's similar but not as bad. According to the edelman tech he thinks it's not bled good enough. I would think it would self bleed eventually but it's never changed. Not sure if I believe the tech guy

I agree. I wished I grabbed the PS pump from the Yukon that I got the clean gearbox from. Unfortunately, they already scrapped it per my last walk. I also need to do some RockAuto part number cross referencing to see if regular vacuum boost trucks have the same pump as a hydroboost truck. I do know the reservoir is different between the 2 as hydroboost has the extra port. I had high hopes with Edelman being a new casting pump getting away from reman, but it doesn't seem to be the answer.

Check the orifice size in the pump. it;s flow not pressure that is the problem. in most cases the OEM pump had the correct orifice size and when it was replaced with the re-manufactured, they tend to us a "one size fits all" for them. I had this issue with my 95 and regrettably returned the core (my factory pump) with the old orifice.

iirc your rig will also have the electronic variable sensor on the back of the pump also. that can be fubar also. but threaded into the back of the pump where the pressure hose attaches is the orifice, behind this is the pressure relief valve and spring. the hole in the center of the fitting that the hose connects to is the orifice. usually it's size it check by fitting the butt end of a drill bit in to it figuring out what size fits best. to get more flow, you simply drill out with the next size bit. there is a limit to how large you can go before you max out the flow the pump is capable of as well as opening up that orifice will also effect it's operating pressures which might require you to pull the valve and reduce the amount of shims in the valve to increase pressure.

on the reman ones the "one size fits all" usually is not intended for the hydro-boost and only accommodates enough pressure and flow for the gear box alone. also the gear box comes into play as well. multiple gear boxes will fit but internal piston sizes can be different depending on the vehicle chassis and GVRW rating. you can usually tell by looking at the end cap of the gear box and see how big the piston is when comparing two boxes. the larger piston gear box will provide easier steering coupled with a pump with larger orifice for flow.

I played this game with my 95 after replacing all the components with reman parts until I got it somewhat right, not perfect, but better.

There is a good writeup online about this in another forum specifically for the GMT400's but a lot of the info will help with yours. I will have to do some searching to find it. iirc it was on the GMT400 forums.

But from what is sound like, the issue is one or the other. a faulty variable EVO sensor on the pump or the orifice in the pump and or gear box piston size. (iirc you did a gear box swap too?)

I actually don't have the variable sensor on my Yukon. I do see its an option for the Denali, and Escalade. I watched a YouTube form BSF explaining what to drill the main orifice out to (IIRC 5/16ths), and to remove any shims in the valving and tighten the nut all the way down to max out at 1350-1400 PSI. If i did this I would do it with the paperweight Napa reman sitting in the basement.

You are correct on the gearbox. I first replaced with with a Cardone as mine leaked from the output. Hindsight I shoulda just replaced the seal. The Cardone was very loose at the output and started leaking from that seal a few months later. My current is a Lares which has even MORE output play, but doesn't leak a drop of fluid. I've inspected the steering system very closely from top to bottom and the only play is in the output at the gearbox. So much you can see it with your eyes while someone wiggles the wheel resulting in nearly 1-inch of steering wheel play side to side. Another point to mention is my front tires wear perfectly so that also confirms to me the tires are pointing in a true direction at least.

 

[DieselSlug]

I spent some time last night trying to re-create the hard steering issue on concrete in the shop and couldn't! No matter if i was on the brakes or not. I think some type of correlation discovery would help solve this better. Going forward I will try to be more cognizant on when it happens and report back.

In the meantime I will find the old Napa (Cardone) pump in my basement and dissect for inspections. Next time I go to the JY I will try to find an original PS pump and hydroboost setup for the parts bin. No more reman or aftermarket for me.

 

[dbrannon79]

You might be having a similar issue like I did on mine. when I started up my truck I had near perfect easy steering but after running for a little bit the fluid would heat up and the steering became harder under slow and idle conditions. what I learned that I was actually cooking the fluid. never found what was causing this as during the summer heat the steel lines on the HB were getting so hot I couldn't hardly touch them. stuck a oven temp probe in the res and put the digital display up on the dash while driving down the road. fluid temps would climb up near 300 degrees. anything over 270 degrees and it would begin to get stiff under idle.

in desperation I installed a trans cooler out front ziptied to the inside of my brush guard and hung a couple of large computer case fans on the cooler just to see what would happen. That fixed my stiff steering issue unless I left it sitting idling in a parking lot for more than 20 minutes. as long as I was moving some, the fluid would stay cool and work fine.

I can only guess there was something inside the HB causing the fluid to heat up since I had replace both the pump and gear box getting the same results.

Hydraulic systems are funny like this where anytime there is a sharp turn or slight restriction where the fluid is traveling and makes a sudden sharp turn in it's path, cavitation occurs creating heat from the high pressures. this could be happening inside the ports of the HB since it's cast iron, sharp edges from the casting molds could cause this. I considered sending my HB out to have ported but the cost was quite high to have this done. I ended up leaving the cooler on my brush guard since that band-aid was working.