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Old 12-16-2011, 03:20 PM   #1 (permalink)
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Default How does air get into the Power Steering system?

03 H6 OBW 65K miles

I've been fighting and intermittent noise that my wife first heard, but yesterday was quite bad and is certainly the PS pump. I had already 'preventatively' replaced the bearings in the serp belt idler/tensioner pulleys.

Then, I read about that fitting at the pump on the end of the hose (suction?) from the tank. So, I took it off and used a heavy grease (dielectric grease) on the o-ring and a little on the mating surfaces. Did some wheels up, engine off/engine on, lock to lock turns. Seems like things got a little better/smoother. Then, after a day or 2, the wife says the noise is back. And it was, really loud. It also seemed there was a lot of fluid under the tank. I thought maybe the suction hose or maybe the tank itself was cracked or ???? Now I think, 'maybe', the fluid just got bubbled out past those baffles in the lid.

So, this morning I went and got some fluid and some real screw clamps. I was also prepared to try some JB weld if i found a crack - or head to the dealership for a new tank. I have reattached the hoses with screw clamps(the one on the return hose seems especially wimpy). 2 at the tank and one at the top of the pump. I have been trying to purge air from the system but, Things don't seem to be progressing well.

I'm posting to see if anyone thinks air can get sucked in underneath the car somewhere. Or sucked in through the PS Pump's shaft? I'd expect everything that leaves the pump would be under pressure and I might find drops of fluid. But I don't. Also, is it safe to just get an o-ring for the fitting on top of the pump from Ace hardware or similar? Will it be metric and the correct durometer/material for this purpose?

I'm gonna keep cycling the wheels back and forth(up on a jack). I've read it can be trickiy to get all the air out. When i look inside the tank, there is quite a bit of 'motion' and only a few bubbles - perhaps from the fluid splashing? But, when I stop the engine and move the wheels back and forth, there's a lot of 'foam' in the tank - almost to the top. So, I wait, and then I try again. The only good thing is that the noise is MUCH quieter now than when I started.

We're coming up on a holiday and if I need a new PS pump or to take this to a real mechanic, I may need to make that decision soon.
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Old 12-16-2011, 03:30 PM   #2 (permalink)
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You can damage any power steering system by working the wheel back and forth with the car sitting still they are designed to assist with turning the wheels when the car is moving. The loads put on the steering system when the car is stationary are very high and the pump/system can be damaged if you proceed to run the power steering back and forth over a long period of time causing all sorts of issues.

The power steering systems are designed to self burp thats why the cap and the small resevior is at the highest point in the system. If its getting noisy have the fluid flushed with proper spec fluid. Noisy pumps are caused by many things but the most common is old fluid and improper fluid levels - and excessive power steering abuse example would be working the wheel back and forth without the car rolling or sitting still while waiting to make a turn and holding pressure on the wheel causing the power steering system to sit there and work while the car is not moving etc.

Also turning your wheels when not moving creates flat spots on your tires too and puts added wear on the steering components. Prior to power steering these issues were a non issue simply because it was obvious to the driver that trying to turn the wheel while not moving was really hard and really not a good idea.
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Old 12-16-2011, 04:55 PM   #3 (permalink)
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Originally Posted by subiesailor View Post
You can damage any power steering system by working the wheel back and forth with the car sitting still they are designed to assist with turning the wheels when the car is moving. The loads put on the steering system when the car is stationary are very high and the pump/system can be damaged if you proceed to run the power steering back and forth over a long period of time causing all sorts of issues.

The power steering systems are designed to self burp thats why the cap and the small resevior is at the highest point in the system. If its getting noisy have the fluid flushed with proper spec fluid. Noisy pumps are caused by many things but the most common is old fluid and improper fluid levels - and excessive power steering abuse example would be working the wheel back and forth without the car rolling or sitting still while waiting to make a turn and holding pressure on the wheel causing the power steering system to sit there and work while the car is not moving etc.

Also turning your wheels when not moving creates flat spots on your tires too and puts added wear on the steering components. Prior to power steering these issues were a non issue simply because it was obvious to the driver that trying to turn the wheel while not moving was really hard and really not a good idea.

I have the front up on a jack so, the tires have no resistance on them. The Subaru document I have outlines the engine off, engine on, routine I've been using, but wheels 'unloaded' as you mentioned.



OK, the bad news; it was NOT residual air. I waited 30 minutes or so, looked in the tank - looks OK. Engine off, a few L2L turns, look again - no bubbles or foam. Run the engine, a few L2L turns, turn engine off, a few L2L turns - huge amounts of foam. Still sucking in air.

Good news; Go to Ace hardware with old, flat, almost square cross-section o-ring from suction housing on top of pump. THEY have one! (be sure to mention it's a METRIC application) I have no idea if it's the proper material for automotive PS systems. It's much more flexible that the old one - which almost felt as hard as plastic. $0.80

Bad news; over-torqued bolt replacing housing onto pump. I decided to test the system anyway.

Good news; MUCH less motion/splashing/bubbles in reservoir, noticeably quieter pump

Bad news; couldn't think of a good way to secure the housing with wire or bands so, decided i have to do something about the retaining bolt.

Good news; It came out even though the head was half-torn off!.

Bad news; another trip to Ace hardware.

Good news; they have a stainless bolt that works! And, evidently, the threads were still good so, everything went back together.


I'm still gonna do a few more 'purge' routines, but things seem much better now. And putting some fresh fluid in (valvoline - I guess that's OK?) is probably good as the old stuff is quite dark. I'll probably try to do a complete fluid change in April at regular maintenance time.
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Old 12-17-2011, 05:39 AM   #4 (permalink)
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Sounds like you got most of your issue solved. The rest of it [foaming] is most likely "old fluid" related.

Hydraulic fluids contain anti foaming agents that dissipate with age so, you get foam.

PS systems are not closed systems so, are susceptible to absorbing moisture [hygroscopic]. Generally speaking the "air" you see as bubbles is boiling moisture [same thing happens with brake fluid].

Change out the fluid and you should be good.

BTW, You can change out the fluid over the course of a few days rather than jacking the car up and doing it all at once.

I usually use a cheap turkey baster and suck as much fluid out of the res as possible. Refill with clean fluid and drive the next day ... do that 3-4 times and it's pretty much all clean fluid.
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Old 12-17-2011, 09:58 AM   #5 (permalink)
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Sounds like you got most of your issue solved. The rest of it [foaming] is most likely "old fluid" related.

Hydraulic fluids contain anti foaming agents that dissipate with age so, you get foam.

PS systems are not closed systems so, are susceptible to absorbing moisture [hygroscopic]. Generally speaking the "air" you see as bubbles is boiling moisture [same thing happens with brake fluid].

Change out the fluid and you should be good.

BTW, You can change out the fluid over the course of a few days rather than jacking the car up and doing it all at once.

I usually use a cheap turkey baster and suck as much fluid out of the res as possible. Refill with clean fluid and drive the next day ... do that 3-4 times and it's pretty much all clean fluid.

ya know, I may just do that until my entire qt. bottle I bought is used, then do a drain/refill in the spring. The old fluid is quite dark. Maybe due to dissolved gas/tiny bubbles - unfiltered air sucked in, etc. Now, tiny bubbles should have an opportunity to purge themselves since it seems the air leak is fixed, but I think the fluid is 9 years old! I don't recall if the dealership ever changed it and I know I haven't.
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Old 01-15-2012, 11:19 AM   #6 (permalink)
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Well I just swapped out Both front CV assy's and car drives Way smoother now, but like my Texas buddy here, with moving the wheel back and forth by hand on the hub while working on it, I foamed up my PS fluid and it's making some of the same sounds.

I have a vacuum tank for changing oil on my jetski, and I changed fluid once before - think I will also do it again to clear out older remaining fluid. Also gonna check that O ring! Cheers!
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Old 01-15-2012, 11:58 AM   #7 (permalink)
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Mine became somewhat noisy at about 3 years and only 15k miles - only really noticeable with the windows down but still...

The fluid certainly wasn't nice and clear like fresh so I gave it several flushings till the fluid in the reservoir looked indistinguishable from new and its been fine ever since.
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Old 01-15-2012, 12:28 PM   #8 (permalink)
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Quote:
Good news; Go to Ace hardware with old, flat, almost square cross-section o-ring from suction housing on top of pump.
i have an '01 h6 and something is making a whirring noise under the hood. i'm thinking power steering pump since the reservoir was all but empty when i bought it last month.

''suction housing on top of pump'' if go look at my power steering pump, will this be obvious?? i have read this a couple of times and until i pasted it here, i thought i was reading ''hose'' in there some where.

the hose with the banjo bolt is the pressure side going to the rack. the other hose is coming from the reservoir. where is this o ring???
where do these pump usually leak fluid?

thanks
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Old 01-15-2012, 12:53 PM   #9 (permalink)
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Quote:
Originally Posted by canubaru View Post
i have an '01 h6 and something is making a whirring noise under the hood. i'm thinking power steering pump since the reservoir was all but empty when i bought it last month.

''suction housing on top of pump'' if go look at my power steering pump, will this be obvious?? i have read this a couple of times and until i pasted it here, i thought i was reading ''hose'' in there some where.

the hose with the banjo bolt is the pressure side going to the rack. the other hose is coming from the reservoir. where is this o ring???
where do these pump usually leak fluid?

thanks

edited - thanx Glenn


sources of whirring noises folks report can also include the serp belt's idler and tensioner pulleys as well as alternator bearings.

The only reason I had any fluid 'leak' was it was being bubbled/foamed so much, it was coming out of the top of the tank (which isn't really 'sealed') and coating the tank and area on the frame/bracket below.

The suction hose is spring-clipped to a small fitting on top of the pump. That fitting is held down by a 12 mm head bolt. When you lift that away from the pump (don't let PS fluid get on the serp belt) there will be small o-ring on the fitting.


I haven't updated anything here for a while. I should mention that I HAVE now used a turkey baster (had to rig a small hose onto the end) to get much of the old fluid out and put fresh Valvoline MaxLife Dexron in the system. Almost a full quart was 'renewed'. I may do this again in the spring. look at 4, here;

http://opposedforces.com/parts/legac...llustration_1/
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Old 01-16-2012, 03:16 PM   #10 (permalink)
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Cool AIR MYSTERY SOLVED! (for me, hope it helps others)

Alright so check this out:

When I swapped both front axle assemblies this weekend to freshen up the CV's throughout (1 was wasted and other had cracked boots), I remember moving the steering rack left/right several times to check the movement of the steering rack, by grabbing the hub.

I distinctly heard fluid bubbling in the steering rack when I did this (bear in mind, car off, wheels off, OB on jackstands so free movement). It seemed odd that I could hear the fluid "squishing" around in the rack.

When I put my car together and drove it, guess what: Groaning, whining, whirring sounds appeared when I turn the wheels. I thought I messed up the pump, and my fluid was filled with tiny bubbles/suds/foam. Thinkning Ineeded a PS pump I read up here first.

Next morning, using a vacuum pump I drew down the reservoir to empty, refilled it with new fluid and gave it a try. No Noise!

Now I thought alright, WTH? So I jacked the car up again, and again by hand moved wheels left/right several times by hand From The Hubs again, and when I put it down and drove the car, the sound was Back!

I replaced the oil in the reservoir yet again (stuff looks real clean now hehe), and there is no noise now.

Can't be sure this will help everyone, but I would wager it's worth considering: A High Mileage steering rack may be able to draw air into the system if you turn the wheels left/right From The Hub with the Engine Off.

Hope it helps!
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