Any ideas?

Twice now in the past week. All of the sudden the steering becomes very tight. If I stop while it is like this and try to turn the wheel I can barely move it and hear a hissing sound but not as loud or distinctive as the whining sound you hear from an empty or very low on fluid power steering pump. Where it gets weird though is it acts like the drivetrain is wound up as if the front and rear diffs have different gear ratios in them and everything starts to bind up or like its in 4Lo locked up and trying to slow turn on asphalt. If I try to turn the wheel with much force (wheels maybe turned a half an inch is all) and then try to move the truck does not even want to move almost as if I was holding the brakes. It will move if I let go of the wheel and let it start off straight and at speed drives okay but I can still feel some tightness of the steering. All 4WD functions are fine and I can cycle it to 4Hi Lock, 4Lo Lock, lock the rear diff in 4Lo, etc and even doing that everything still acts bound / wound up. First time a couple of days ago I drove it on home like that (about 25 miles) and the next morning I checked the power steering and brake fluid - brake because I reckon it could be something to do with the hydroboost and both were fine and it drove fine. This morning coming into the shop was fine until about a quarter mile before I got to the shop it started it again.

Just not really sure on this one. Hyrdroboost? Transfer case? Torque converter or transmission? I need to have this on the road but I do have another vehicle I can drive (my GMC Sierra is in pieces right now) but its an older 1999 Blazer and it needs updated injectors.... it runs and drives okay but falls flat on its face and bogs down if you give it more than about half throttle.

 

there is a TSB on the truck applying the brakes while turning that one involves replacing the Hydroboost.
the other TSB on hard turning while braking or parking maneuvers involves replacement of the power steering pump.
there is a special tool to test the pump. it has a pressure gauge and a valve. the procedure is to put it on the pressure side of the pump and you dead head (close) the valve for 2 seconds. it should hold 1100 psi. if it does not then the pump is worn. also if you see the needle on the gauge vibrate excessively means it can have internal leakage usually the front and back walls of the pump are scored.
i have been noticing the hard parking maneuvers myself in the last month. i just do not feel like opening that can of worms at the moment.
you know how that goes.......
you want to replace the pump then realize the pully is seized on, the resivoure is ****. then you look at the power steering lines and there ****. then the lines to the hydrobost also not well. then you notice the steering rack is wet followed by the steering shaft has play the steering column is squeaking when you turn and has play.... as you look over you have a missing exhaust bolt on the number 8 cylinder ect.. ect.... you finish the job then go to make a left turn and the truck applies the brakes.. Yay time for a hydroboost install.

 

LMAO.... yeah I know. Everytime you start a project like this it snowballs with a ton of "while I'm in here" stuff. I've seen a couple of recall ones that do not apply to my year. I need to look through the docs in the eSI system and see what is in there. About to leave the shop and going to try driving it home again and hope it acts right.

 

sorry forgot to post the link.https://www.nhtsa.gov/vehicle/2003/H...Communications got carried away thinking about it lol. hydroboost systems damage steering pumps (i think the boost spring inside might weaken over time eventually wearing out the pump housing by not pushing the desired psi) i would start they journey there.... sigh

 

Drove it home last night and back to the shop this morning and its still acting up. After spending a few minutes messing with it this morning I think you are right. Its the hydro.... While idling this morning I turned the steering wheel and at the same time you can watch the brake pedal start going down by itself so something is amiss. Took the master cylinder bolts loose while the brakes were still holding and they immediately released so steering is causing the hydro to apply the brakes. Never felt any vibration so hoping I did not warp the rotors but I'm sure the pads have some extra wear on them.

Going to go ahead and get an ACDelco hydro and swap it out next week..

 

you had rebuilt that one before right?

 

Yeah.... Seems to have been fine up till now.

 

i was thinking of going the rebuild route like you when the time comes but now i am in a conundrum lol. i was thinking new steering pump GM say to go with the 2009 pump as they have worked out some early pump failures. and a rebuild of the Hydro boost but now you have shattered my dreams LOL.