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.