Hard Steering

[Harley Rider]

2005 GX with 138K miles (I'm original owner and only driver). At about 135K the steering started to get tight off center and wouldn't self-center. As I turned the steering wheel it would get tight-easy-tight-easy in either direction. Serpentine belt was fine and fluid was full, though there was indication of moisture in the fluid (tan streaks). Fluid had never been changed, so shop changed fluid and flushed the system. All was well for almost 2,000 miles, but started to tighten up again after 2,000 highway miles over several days. Now it's just tight, no tight-easy-tight-easy. It's drivable, but just takes more effort to stay straight. 

Toyota in Waco, Texas (no Lexus shop on my route) has no idea what the issue is. Fluid is full and no sign of moisture. They checked and U-joints in steering column are fine, steering links and ball joints are fine. Steering got a little easier after cooling off, but tightened up again after a few miles of driving. 

Toyota shop is going to flush the steering again tomorrow and make sure system is bled, but other than that, they have no idea. Seems to me that it could either be the pump or rack, or somehow air is getting into the system, but there are no leaks. 

Any ideas??

[Lexus_DK]

Does the power steering pump make any unusual noises while the engine is running? Check the tension on the belt with engine off, make sure it's not loose and inspect it while it's running. And does the steering issue occur at any speed?

[Lexus_DK]

Have the Toyota technician run a health check with their scanner and see if any power steering codes are present.

[Lexus_DK]

Also have them perform a pressure check on the pump and rack. There's a gauge tool they can hook up in place of the high pressure line.

[Harley Rider]

Update 4/26/17: At my request, technician at Jeff Hunter Toyota in Waco, Texas (why is there no Lexus dealer in Waco?) flushed the steering system - again. Steering is better than pre-flush, though still not back to normal, but I've only driven 30 miles around town. I still have 1,800 miles to go before I get home, so we'll see how, or IF, this holds.

Belt is tight, no noise from pump, occurs at any speed. I don't believe they have run a scan for codes, nor has a pressure test been done. Both are on the list for when I get back home. Thanks, Lexus_DK, for the suggestions.

[Harley Rider]

Update 5/1/17: Tighned up again while still in Texas. A little tight off and on through Louisiana. Sometimes tight, sometimes just fine in Mississippi. Left Mississippi yesterday and it was fine most of the day, but seemed a little tight in Tennessee last night. However, it was normal for the last 520 miles to Michigan today. Really baffling.

[fozzir]

Is the rack leaking? Slide the boot off and see if there is any fluid.

[CascadeGXer]

@Harley Rider Did you get to the bottom of it? Any updates. I have the same issue with my 08' GX470 with 125k miles and about to swing by the mechanic to get it diagnosed. Steering tension eases as the car gets warmed up and is most noticeable when the car is cold. 

[Harley Rider]

Late update: Fall 2016 Lexus of Ann Arbor replaced the rack and steering shaft. They said they couldn’t separate them, so I’ll never know which one it was, but problem solved. Handles like new.