Loud Squeal When Turning

I have a 2003 Trailblazer with 160,000 miles on and in the mornings when I back out of my garage and make a turn to go straight, in either direction, it makes a loud squealing noise. I have replaced the serpentine belt, the belt tensioner, and the power steering pump. I have taken it to my mechanic for this reason and he does not know what it could be. Any ideas?

It may be coming from the rack itself.
Remember that when you turn the rack is hydraulically forcing a piston through a chamber. If the seal on that piston is worn or the rubber seal has hardened, that can squeal. Unfortunately, this won’t show up as external leakage, so it’s tough to verify.

If anybody here knows of a way to test this on the vehicle, I’m open to the learning opportunity.

If the noise is coming from the steering wheel, it could be the steering column that needs to be greased. Bad wheel bearings can also be the problem.

I forgot to ask… 2WD or 4WD?
It may not be coming from the hydraulic components, but the articulating components.

FWIW . . .

I’ve seen a few horrendously bad lower ball joints make squealing noises while turning

It shouldn’t take too long to figure out if the ball joints are any good, or if they are the cause of the noise

I’d guess it is something on the belt routing path that also includes the power steering pump. You could try using a length of garden hose as a sort of stethoscope to narrow down where it is coming from maybe. One of the pulley bearings/bushings on that belt path may be worn out. Another idea, remove that belt and see if the noise goes away. Would confirm the above hypothesis anyway. Be aware remove the belt may prevent he water pump from spinning, so only for a short time.

It is a 4WD