I have been trying to pin point this noise. when turning left only, I have a groaning noise. I changed out the power steering fluid and flushed the system. Still have the same noise. My question is, can I disconnect the intermediate steering shaft and then go ahead and turn the steering wheel? If I disconnect the shaft it will not be connected to the rest of the steering system. If I still hear the noise that would tell me it is in the steering wheel its self or the shaft and not the power steering pump, steering gear or other steering components on the bottom end. I have done a intermediate steering shaft lube before. When I did that I was told to bungee the steering wheel to the gear shift leaver so it wouldn't move or mess up the clock spring. Thiswas on my 99 and I took the shaft complety out.I currently have an 04 model.If the shaft is only disconnected on the bottom end, I don't see how it could hurt to turn the steering wheel with it disconnected.
Any insight or knowledge on this would be appreciated.
Thanks in advance

 

may be an old thread, but heres your answer,

its a design flaw inherent to the saginaw boxes in the GM trucks, theres something in the internal porting that causes cavitation of the fluid on a left hand turn, this is also exacerbated with higher fluid temperatures. i had gone through multiple boxes with this issues of the groan on a left turn only. after replacing everything ( i mean everything) i ordered a redhead box, which is re-machined, not just rebuilt. and the issue was gone for the better part of three years. the issue started to come back this summer as temperatures rose. its definitely a temperature related issue as well as an internal issue. i hope this sheds some light on the problem. it is the box, good luck trying to find one that dosent groan... im on my 9th ( ended with a redhead)