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Registered
2009 OB 2.5i 4EAT
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298 Posts
Discussion Starter #1
Hey guys,

If you frequent the Gen 3 forum you may know I've been waging a war against my power steering. It's been at a 'stable' place for a bit but now I need to get to the bottom of it.

PROBLEM
Steering when going over bumps at low speeds. Also manifests itself as steering sharply to left or right when coming to a stop. Here is a video of me going slowly in a pretty lumpy parking lot at work. Hard to see, plus I had to correct at times, but you get the idea: it will not hold itself straight when going slowly over uneven terrain. It requires some effort to maintain it going straight. The steering seems to be OK when at speed (30 MPH+?) Additionally, I get some 'oscillation/knocking' when hitting bumps at slow/tight corners.

There is also an air leak evidenced by constant stream of fine, sparse bubbles(see here. I have not been able to track down the source of this. It never foams. Performing bleeding/burping does not impact this.

WORK DONE
-Replaced suction o-ring, suction hose(aftermarket), suction hose connector, reservoir return hose (aftermarket).
-Replaced pump and rack with used pieces (both from Legacys, 07-08 range <60K miles).
-Suspension seems OK, replaced shocks with not affect. Car has had an alignment.


PATH FORWARD
I want to replace the pump with my old, rebuilt unit when weather permits. However, I'm curious if y'all think the pump is even the culprit? Could it be the rack? I don't really know rack operation well enough to interpret the symptoms to the physical source. The FSM is extensive in tests, but extremely vague in the causes of the symptoms.

Further, I don't understand what the source of the air bubbles is. The only parts that are original at this point is the reservoir and the pair high-pressure/return line that connects to the rack. The the best of my knowledge and ability, all connections are tight, with no leaks present.
 

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Registered
2012 OB , 2017 Impreza
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3,294 Posts
Air in the powersteering system is ALWAYS a leak in the vacuum side of the system. (all other portions of the system would leak fluid)

The "vacuum side" is from the reservoir to the pump. This includes Oring and rarely the seal on the pump-shaft.
 

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Registered
2009 OB 2.5i 4EAT
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298 Posts
Discussion Starter #3
Air in the powersteering system is ALWAYS a leak in the vacuum side of the system. (all other portions of the system would leak fluid)

The "vacuum side" is from the reservoir to the pump. This includes Oring and rarely the seal on the pump-shaft.

Yeah, that's what I was advised, and why I replaced the hose, connector and o-ring. The hose is aftermarket but seemed good quality, fits nicely.. I even did new clamp + tried screw down clamps. I'll swap the pumps, I guess it's not impossible the junkyard one was a dud. Just need a break in weather and some free time on my end.

I think someone mentioned a crack in the reservoir as a possibility, but that seems far fetched to me. I imagine it'd leak.
 

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'18 OB 3.6R
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64 Posts
My guess on the bubbles is the seal where the top hose from the reservoir goes into the pump itself. I know you've already replaced it but I had a similar issue and replaced it three times with no fix - but i put a slightly oversized (oversized outer diameter) o-ring on there and it sealed up finally. I definitely had to cram it in there lol.

Are you on stock sized tires? I know a lot of times that trough wander / tramlining can be caused by wider tires + alignment issues. Although I don't think we can adjust caster on these cars if that was out of whack from front-end damage/potholes/hitting a curb at some point it'd cause some weirdness.
 

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03 H6 OBW & 06 WRX Sportwagon
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17,711 Posts
inner tie rods and that bushing at the rear of the lower control arm should be checked.

there should be NO bubbles in the ps fluid. (OK, maybe one or 2 every few seconds from the return stream splashing) certainly no stream of bubbles.

as mentioned above, try a different o-ring. I had an asst. pack of o-rings from the parts store that were all chinese crap. The Interdynamics kit I got from amazon 'seem' to be better.
 

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2004 Outback
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42 Posts
OP, I'm interested to hear what solution you come to. My 04 OB has similar issues, though I've put it on the back burner because I need to replace struts and some suspension bushings. When I come to a stop the steering wheel will quickly turn on its own. This happens during the last few feet of the stop. Sometimes the wheel turns left and sometimes to the right.
 
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