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Old 02-01-2011, 03:33 PM   #1
68Cadillac
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Default DIY: Power Steering Pump Rebuild

UPDATED master O-ring replacement list in post #9

I own a 80000+ mile WRX. Love it. Paid for, turbo, lots o' space and light. I always check my fluid levels on every fuel fill-up and noticed 4 weeks ago that the Automatic Transmission Fluid (ATF) in the power steering pump reservoir was down to the "Min" line. I filled it back up to "Max" line, and drove away thinking nothing of it.

Week later, I'm notice drips and small puddles of fluid on the garage floor and driveway.


Open the hood and the ATF is down to the "Min" level again. My shiny pulleys mock me.


After a bit more looking I see what looks like ATF (because it's red) on the top of the engine block right behind the PS Pump caught in the ribs of the block casting. I also see it pooling in the area just in front of the PCV valve (no photo). The above photo was taken only 2 days after soaking up the fluid that was there from before.


Also see fluid on the timing cover just under the PS pump. I don't have a photo but I've seen fluid dripping off the oil filter.


Looking at the PS pump itself I notice red fluid on top of it in a little recess. This is right on the parting line between the two halves of the pump. This photo was taken leaning over the engine with my head near the intercooler looking toward the front of the car.

I call Ken up at my local Subaru and ask for a rebuild kit. Ken quotes me a price well over $400. $400, for a rebuild kit?! Oh no sir. Your pump is unserviceable. That's the price for a new one. Ken's a good guy so I thank him for his time and hang up.

Look up the price of a rebuilt one from Rockauto. $122 if you exchange it with your core. $162 w/o core exchange.

To the web! Turns out a few guys have successfully serviced the unserviceable PS pump that we share. Big thanks to Maxxell and his thread over on IWSti and Hwy61 and this thread here. So if you own one of the following this post might be for you:

SAAB 9-2X AERO (2005, 2006)
SUBARU IMPREZA WRX (2004, 2005, 2006, 2007) <-----me
SUBARU IMPREZA WRX LIMITED (2006, 2007)
SUBARU IMPREZA WRX STI (2004, 2005, 2006)
SUBARU IMPREZA WRX STI LIMITED 2007
SUBARU IMPREZA WRX TR (2006, 2007)

Based on Maxxel and Hwy61 measurements I've ordered three new o-rings from McMaster-Carr.

I decided to get upgraded FEP-encapsulated O-rings because McMaster-Carr had four materials that rated "Excellent" for hydraulic fluid resistance and FEP was the cheapest in the sizes recommended in those two threads. ATF is a type of hydraulic fluid. Kalrez Perfluoroelastomer O-rings were also recommended, but at $180 per ring I passed.

I ordered part numbers:
9319K165 Fep-encapsulated Silicone O-ring As568a Dash Number 040
9319K15 Fep-encapsulated Silicone O-ring As568a Dash Number 015
9319K14 Fep-encapsulated Silicone O-ring As568a Dash Number 014

For all three it ran me about $13. A bit spendy for O-rings but these FEP rings rate better than Buna-N which is probably what is in the pump now and failing. Apparently they suffer virtually no expansion when exposed to hydraulic fluid and are good up to 400 degrees F.

Come to find out o-ring sizes are measured in "Dash Number". So while you can order them by dimension, dash number will get you there faster.
Dash Number 040 is the big ring (~ 3" OD x 2-7/8" ID x 1/16" thick)
Dash Number 015 is smaller ring inside the pump (~ 11/16" OD x 9/16" ID x 1/16" thick)
Dash Number 014 is the ring that easy to get to on top of the pump ( ~16mm OD x 11mm ID x 2.5mm thick)
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Last edited by 68Cadillac; 01-23-2014 at 06:55 PM. Reason: Rehosted images
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Old 02-01-2011, 03:35 PM   #2
68Cadillac
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*Update 2011 02 03 Dash 040 o-ring does not fit. It's not even close. Measured and ordered a Dash 037. Also ordered an additional Dash 014.
*Update 2011 02 08 To tired to do a write-up today So I just attach all my photos to post numbers 6, 7, and 8.
*Update 2011 02 09 Finished write up. Added master O-ring size list to post 9.
*Update 2011 04 29 Updated post 9's O-ring list with cracky's input and trials.
*Update 2014 01 23 Rehosted images from the first three pages on imgur.com. When your threads become popular, photobucket become "the sux".

Last edited by 68Cadillac; 01-23-2014 at 08:26 PM.
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Old 02-02-2011, 12:11 PM   #3
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Sweet Nice! I was thinking about this exact thing. I have a extra PS pump back from my @$$hat days. Regardless of my current one being ok I may rebuild it just because. Good thing to do before AutoX season.

Id like to find a lil bigger pulley for the pump to I can rev the engine while turing the wheel and not be "as" bad for the system.
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Old 02-05-2011, 07:10 PM   #4
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I'd love to hear the results,I have the same leak.
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Old 02-08-2011, 07:08 PM   #5
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I rebuilt the one on my 90 Legacy. Here's pics and a thread on the Legacycentral BBS with more info about the bearing.

http://www.main.experiencetherave.co...psteeringpump/

http://bbs.legacycentral.org/viewtopic.php?f=11&t=24143
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Old 02-08-2011, 08:25 PM   #6
68Cadillac
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Here's what the FEP-encapsulated O-rings look like. This is a Dash Number 040, 015, and 014.


FEP-encapsulated O-rings Close up. They're firm to the touch and don't feel at all like a standard ring. I guess the red is the FEP and the clear sheathing is silicon encapsulation. You can just make it out in the photo.


Three days later after the photo in post 1 and I see more red fluid fill up the pools on the engine block.


Begin removal. I recommend cracking open the cooling system. Makes it so much easier to get at 2 bolts on the bottom of the PS pump bracket. I recommend taking the pulley off BEFORE you take the pump off the block. I had to fire up my impact gun at 95 psi to loosen that nut with it off the car. And I live in a dry desert, so my **** doesn't get all rusted and corroded.


Now I can see where the fluid is leaking out by the trail of ATF and dust slurry caked on the side of the pump.


With the Pump and it's bracket removed I get to see the full extent of the leaking. It's on everything and it stinks.


Three bolts remove the PS pump from it's bracket. One long one from the back and two smaller ones from the front. The pulley needs to be off to get at the two front bolts. Once out of the bracket you can open the back of the pump by removing four bolts. Just lift the back off. I tapped it with my deadblow hammer and it came right off.


And I ordered the wrong O-ring. ****! Needed a Dash 037 (Dash 040 is way too big)


Dash 014 fit perfect on the inlet. That's a Dash 015 on the towel.

Last edited by 68Cadillac; 01-23-2014 at 07:02 PM. Reason: rehosted images
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Old 02-08-2011, 08:26 PM   #7
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Measuring for the big ring on the back of the pump. 64mm inside diameter. ---> Dash 037


69 mm outside diameter.


Thats why a Dash 040 won't fit.


Here's my trouble o-ring. The leaking mess maker. A Dash 014 O-ring (13mm inside diameter). Also a good shot of the rotor and 11 veins inside the pump.


It held the ATF fluid in around this fitting and the spring. That spring is what allows this PS-pump to vary its displacement. This pump is a Variable Displacement Rotary Vane type.


FIVE DAYS LATER. The Dash 037 arrives. This also shows why I needed to order it and couldn't just reuse the old O-ring. When I took it off, it cracked right in my fingers. I had the pleasure of making that call to the Little Woman five days prior, "Honey, we're down to one car... again." A dash 015 ring goes at the top just above the 037. You can see it sitting in it's groove.


With the rotor and vanes removed you and get at the valving body at the front of the pump. This is the back side (i.e. this side to the rear of the car). Be careful removing the rotor and vanes. The vanes aren't attached to the rotor and will just fall out. The gold/brass side of the vanes go out, by the way.


This is the front side of the valving body at the front of the pump(i.e. this side to the front of the car). Notice two o-rings in this photo.


Having learned my lesson about messing with old O-rings, I just measure this one with it in place. 56 mm O.D.


50 mm I.D. Dash 033. You might want to think about getting a Dash 136 one for this position instead. It's 0.8382 millimeters thicker than a Dash 033 but with the same inner diameter. I mention it because this o-ring looked and measured thicker than all the other o-rings in this pump. In some ways it looked like a square cut ring in which case it would be a Dash 136 Square Cross Section. Good luck. PM me if you find out what it is, and I'll post it in this thread on the master o-ring list.

Last edited by 68Cadillac; 01-23-2014 at 07:12 PM. Reason: rehosted images
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Old 02-08-2011, 08:26 PM   #8
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28 mm O.D. for the ring furthest forward on the inside of the main body of the pump.


24 mm I.D. Dash 021. UPDATE: Now recommending the Dash 119. The thinner -021 has had too many issues on too many pumps.


Then there's the standoff on the high pressure side.


Which has a 13mm I.D o-ring on it. Another Dash 014.


Took a few measurements of the bearing on the pump. No way was I going to press it out just to measure the thickness but its I.D. is 17mm.


40mm O.D. for the bearing.


On the very back of the pump there's a sensor and an O-ring. It's O.D. is ~15mm. I'm squishing it with the calipers in this photo to get it to stay.


The all important I.D. is 12 mm. So a Dash 013 O-Ring.

Last edited by 68Cadillac; 03-12-2014 at 01:04 PM. Reason: rehosted images
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Old 02-09-2011, 06:16 PM   #9
68Cadillac
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Master O-Ring & Part Replacement List
for
Powersteering Pumps
found on:
SAAB 9-2X AERO (2005, 2006)
SUBARU IMPREZA WRX (2004, 2005, 2006, 2007)
SUBARU IMPREZA WRX LIMITED (2006, 2007)
SUBARU IMPREZA WRX STI (2004, 2005, 2006)
SUBARU IMPREZA WRX STI LIMITED 2007
SUBARU IMPREZA WRX TR (2006, 2007)

To completely rebuild this guy you'll need the following:

1 - AS568A Dash Number 136 O-Ring
1 - AS568A Dash Number 119 (or maybe -021) O-Ring (Although myself and a select few others got the -021 ring to seal many other's did not. I can no longer, in good conscience, recommend the -021 ring. Just get the 119 it's 1/32 inch [~0.8 mm] thicker having the same I.D. as the -021 and seems to work in every pump.)
1 - AS568A Dash Number 037 O-Ring
1 - AS568A Dash Number 017 O-Ring (behind the 10mm allen 'hex plug')
1 - AS568A Dash Number 015 O-Ring
3 - AS568A Dash Number 014 O-Rings (that's three total for full replacement)
1 - AS568A Dash Number 013 O-Ring (Some have suggested to only get a Buna-N ring for the 013. This is the one that seals the sensor to the back of the pump. It is difficult to install if you get the FEP, but not impossible. Read Mike-easy's assessment here. Buna-N if you want to be safe, with less hassle.)
1 - Bearing 17mm I.D. x 40mm O.D. and 12mm width. Prices range from $6 to $106 from McMaster.
1 - Oil Bearing Shaft Seal 20mm I.D. x 32mm O.D. and <= 9.3mm in width. "<=" means less than or equal to.

O-ring materials known TO WORK rebuilding this powersteering pump:
Buna-N - Used in all OEM pumps. Inexpensive and will last as long as OEM ones.
FEP Encapsulated - Upgraded materials with upgraded prices. Better than Buna-N


O-ring materials known NOT TO WORK rebuilding this powersteering pump:
PTFE - Too hard as tested by Othon
Viton® Fluoroelastomer - Tested by Othon

Regarding the Seal: I found one at RocketSeals.com P/N 20X32X8-MOS/D which looks like it would excel as a replacement. The I.D and O.D. need to be exact. The width just needs to be <=9.3mm. RocketSeals P/N 20X32X8-MOS/D has been tested and found to fit perfectly by our very own othon. Thanks guy. Also a report of Carquest seal PN# SLS 222020 OR INTERCHANGE # AE0997E0 WORKS GREAT for the shaft seal.

BeratE put together a list of the Part Numbers for the FEP encapsluated O-rings and a great bearing from McMaster in this post.

2013-Feb-17: Reliability update on FEP Encapsulated. No issues on my PS Pump. No leaks. No pulsing. No ATF consumption. Works without problems.

2013-Apr-13: Reliability update on FEP Encapsulated. Still running strong. -021 O-Ring doing fine on my rebuild. A few reports of it being too thin for some pumps. -119 is next thickest size, if that applys to your pump.

2013-Nov-15: Reliability update on FEP Encapsulated. No issues. No leaks.

2014-Mar-12: Now recommending the -119 ring over the -021. Too many people have had issues with the -021.

Last edited by 68Cadillac; 03-12-2014 at 01:02 PM. Reason: updated list
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Old 02-09-2011, 06:45 PM   #10
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Here's a link to the AS-568A O-ring sizes in chart form. Nerd up.
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Old 02-10-2011, 12:35 PM   #11
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And two day later.


It's leaking again.


But from a different seal. Seems like just the act of opening up the system to even look at the O-rings on a pump this old causes them to fail on reassembly. The more I mess with this the more I'm starting to think that getting a rebuilt one from autozone for ~$120 with core exchange is not such a bad deal. This is really frustrating. But "In for a penny; in for a pound". I soldier on.


Here's a photo of the hex fitting where my so called mystery O-ring probably rests. I am not opening that up.

Last edited by 68Cadillac; 01-23-2014 at 07:19 PM. Reason: rehosted images
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Old 02-11-2011, 12:14 PM   #12
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keep the faith! All across the country these little pumps are squirting into the snow...
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Old 02-11-2011, 12:17 PM   #13
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Quote:
Originally Posted by 68Cadillac View Post
I'm notice drips and small puddles of fluid on the garage floor and driveway.
I found the blood spots after snowmageddon-was not enthralled.
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Old 02-15-2011, 11:59 PM   #14
68Cadillac
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Proud (and ashamed) to post that I stopped the leak. I failed to propertly tighten the hollow bolt on the top of the pump on the pressure side. Guess when it's only on with 10 ft/lb it's tends to leak.

Success!

I serviced the unserviceable power steering pump. Fuji Heavy, I give you the .

Last edited by 68Cadillac; 02-18-2011 at 02:11 PM.
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Old 02-18-2011, 12:03 PM   #15
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Subscribed for the love of rebuild threads. Thanks for all the photos.
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Old 02-18-2011, 12:13 PM   #16
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Great Job! I love these rebuild write ups
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Old 02-18-2011, 02:03 PM   #17
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Thanks. I love adding to the collective knowledge base that's given me so much.
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Old 02-18-2011, 08:54 PM   #18
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Quote:
Originally Posted by 68Cadillac View Post
Thanks. I love adding to the collective knowledge base that's given me so much.
whats the order of assembly for the internals? i have a pump torn apart on the bottom of my shop cart cause i was gonna do the same thing but it just sat for months, and now i forget the order
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Old 02-18-2011, 10:30 PM   #19
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Quote:
Originally Posted by Csquared33 View Post
whats the order of assembly for the internals?
Reverse order of disassembly?
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Old 02-18-2011, 10:39 PM   #20
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Quote:
Originally Posted by 68Cadillac View Post
Reverse order of disassembly?
yea i got it
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Old 02-19-2011, 03:22 PM   #21
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ill be rebuilding my spare shortly. ill be replacing the bearing too, ill let you know what works
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Old 02-19-2011, 11:54 PM   #22
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Great write up!

I have to ask. ok I have no leaks. Yet it has the jumping compression. Where it was run low on fluid for a while. Is there a fix for this issue? Thanx
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Old 02-22-2011, 09:31 PM   #23
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Great write-up very thankful for the info. I have a 2004 STi with 110k on it. My p/s pump is leaking and can't wait to get it off and rebuild it. Since the cooling systems is coming off I'm going to change timing belt, water pump and thermostat too,not to mention they are over due to be changed. Thanks again for you write up you save me some hard earned $$$
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Old 02-23-2011, 01:22 AM   #24
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Regarding the FEP encapsulated silicon type o-rings: The FEP is the clear outer layer and the silicon is the red part in the middle. The good news is that the FEP layer is pretty tough against hydraulic fluids and synthetic oils. The silicon is in this case essentially just a filler since it has very low resistance to oil/hydraulic fluid. Another plus is that the upper temperature range is much higher than what your pump will ever see. However, I'm curious to see how those rings hold up over time since they are so much harder than the originals.

You can also use either NBR ("Buna-N") rings which are as you pointed out *probably* what's in there to begin with, or HNBR rings which have a higher operating range. Based on the way your rings broke I'd say that heat is an issue and go with the HNBR rings. McMaster sells them in bags of 25-100 for about what you paid for single rings. If you look around you might be able to find smaller bags or even individual rings for a lot less.
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Old 02-23-2011, 03:35 PM   #25
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Thanks for the Tip Rambler323 Just Ordered from the O Ring Store.com

1 x 037 HNBR70 Green O rings = $1.28
1 x 021 HNBR70 Green O rings = $0.52
1 x 015 HNBR70 Green O rings = $0.32
1 x 014 HNBR70 Green O rings = $0.32
1 x 013 HNBR70 Green O rings = $0.32
1 x 136 HNBR70 Green O rings = $1.36

Plus $5 shipping

Last edited by rlucy18; 02-24-2011 at 12:27 PM.
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