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Saturday, April 02, 2016

Power Steering Pump rebuild

Taking a break from broken dams for a moment...
I recently did some work on the new (to me) little Subaru.

The car is just about perfect, but it had a minor leak that I traced to the power steering pump.  I found the pump quite low on oil one day, way down below the dip-stick, which was a little scary.

The power steering pump is directly under the reservoir with the yellow cap, and driven by the little black pulley.  You can't even see it in this picture, which should give you a clue how difficult this "simple" fix turned out to be.

The power steering pump was pretty difficult to get loose.  I had to drain the reservoir by removing the rubber hose to the left of it.  Next I had to stick a socket down inside the reservoir to remove a bolt so that I could get the reservoir off the pump.  Only after removing the reservoir did I have access to the bolts that held the pump to the engine.

After quite a while, I managed to remove the pump, and this is how the engine looked at that point:  I had to clean off quite a bit of power steering fluid and grime before re-installing the pump.

The oil reservoir I set aside on some rags until I finished with the pump.

The pump was pretty crusty with caked on oil/grime.  It had probably been leaking for quite a while.

I cleaned the pump up with some carburetor cleaner and wiped it down really well, as I didn't want any of that grime getting inside the pump.  The internals have a fine finish and contamination would probably ruin the rotating parts.

Below is the cleaned-up pump before I started, with the kit gaskets to the left, and an exploded drawing of the pump on the right.  There are no step-by-step instructions for this operation.  This is a kit for several different pump models, so you have to figure out which gaskets and o-ring go where, and which parts aren't needed at all.  Ha!

This is what you see when you split the pump open by removing the back.  It's a dual cavity sliding vane pump.

Below is an animation showing how a single cavity vane pump works.

After several tries, and having most of the vanes fall out of the rotor, eventually I got it all back together.  I installed it, replaced the reservoir, connected the fluid fittings, added new fluid, and tightened the belt.  

O'Reilly Auto parts wanted $125 for a replacement pump.  The rebuild kit was $17, and it made for an interesting day and a blog post.  Here are a couple of current pictures of the installed pump with ~80 miles on it.  No sign of leakage as yet!


Lastly, here's the video I watched before doing this, showing how it's done.  There is a great deal less drama than I ended up dealing with :)

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