2011 Subaru Impreza / Power Steering Issue


#1

Symptom
Earlier today, I noticed my 2011 Subaru Impreza was stuttering when I turned the wheel completely left or right. Not only was it stuttering, but the battery light would flicker as though the battery was going to die. I made it to Auto Zone to check my battery and alternator, both of which passed. However, while I was showing him the issue, when I turned the wheel completely right or left, the power steering pump pulley would stop spinning, then struggle to start spinning again. However, the belt would continue to run as it’s being pulled by other accessories, but the power steering pulley would still struggle to spin. (Over time, my guess is that friction would eventually burn up the belt and cause it to break.)

Recent Work
I’ve had the A/C belt, serpentine, and the timing belt (with all accessories) replaced within the last 5,000 miles.
I’ve replaced power steering fluid within the last 2,000 miles.

This morning, I tried removing the reservoir cap and turned the steering wheel to remove air bubbles. It didn’t help. The hesitation and stuttering is getting worse.

Diagnosis
At first glance, I would guess the power steering pump is failing, but I’m not a mechanic, therefore it’s just an educated guess.
What do you think?


#2

Seems early for belt replacement, but I would start there. I would also clean you battery cable connectors.


#3

It sounds like the belt isn’t tensioned properly. Could be a worn belt, could be a faulty tensioner.

But it could also be a failing power steering pump.

I think a qualified local mechanic would be a better choice to have this checked out instead of AutoZone.


#4

When you turn the wheels all the way to the stops, that puts a lot of load on the PS pump. So if it was verging on the point of failing, hitting the steering stops could be enough to put it over the edge. And a failing PS pump could put enough load on the engine via the belt to cause the idle rpm to drop enough to turn on the battery light, and that low rpm would also cause the engine to appear to stumble. So I’m guessing an about to fail PS pump.

Edit: One thing to add, since you’ve had some work done in that area, it is possible the pulley’s weren’t re-installed correctly, and are now incorrectly aligned. That could conceivably cause this problem too. So have your shop check the pulley alignment, before considering to replace the pump.