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Discussion Starter #1
[Introductions] Hi! First post here, and first Subaru. I'm located in Kokomo, IN; I just moved here from Sioux Falls, SD.

[The car] 2007 2.5 basic (steel wheels baby!), 135k miles, purchased last April. New head gaskets and timing belts when purchased. Battery seems good as it starts fine even in -0 F temps. I've searched here and elsewhere and haven't found much help yet.

There's an incredibly loud whining noise when (1) the engine is cold and (2) when turning the steering wheel. Sometimes turning the wheel just a little makes the noise, sometimes you have to turn it all the way. However, the noise is not present when revving the motor and turning the wheel at the same time (even when engine is cold). Also, I should mention that the noise is only present when ambient temps are cold, say below 40 degress F, getting worse as the temp approaches single digits.

PS fluid is good; no leaks, no bubbles. I had my wife generate the noise while I stood by the engine and listened--I'm pretty darn sure the noise is coming from the alternator.

I first noticed the noise as temps started getting cold last fall. As I said I purchased the car in April of 2017.

Any ideas? Any typical issues I should check? I'm trying to avoid taking it to a shop and paying an hourly fee to have them troubleshoot stuff.

Thanks. I've enjoyed browsing the forum the last few months.

Jesse
 

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2005 Outback R LL Bean 3.0 H6 w/ 5 speed sport shift
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Welcome, sorry it has to be to solve a problem!

It's about -13 degrees there isn't it? I see you've looked pretty hard at the PS pump.

I have read many posts where the owner thinks the noise is coming from the alternator but what is happening is the noise is transferred through the mounting bracket from the PS pump.

My suggestion is to make certain you have the reservoir suction hose actually tight at the PS pump (I had to use a radiator type hose clamp since my hose was getting brittle at the pump). Then, jack the car up and with the engine off, turn the wheels left then right lock to lock 10 times or more. Then start and turn lock to lock once. Then repeat the lock to lock process with the engine off another 10 or more times.

This process seems to have worked for many here and it has worked for me personally.

I would focus on the PS pump, I believe that's the culprit.
 

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06 Outback 2.5i, 05 Outback Limited
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Might be worth replacing the O-ring on the top of the pump, could be shrinking when it's cold and letting some air in and causing the pump to cavitate a bit. It's under $5 and takes two minutes to change, and if it hasn't already started leaking it will. #JustSubaruThings ;)

But, for what it's worth, both of our 05 and 06 2.5 Outbacks have whining power steering pumps until the fluid warms up when it's below freezing. I don't plan on changing anything -- it's just the nature of hydraulic fluid when it's cold.
 

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2005 OBXT Ltd Obsidian Black 5MT
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Woah, Kokomo, small world.. I'm originally from Marion, about 20 minutes East of there. Still pretty much the middle of nowhere though. Fun trivia fact: at one time, and maybe still true, Kokomo had more restaraunts per capita than anywhere else in North America.

Anyway, we're here about cars.

When were the accessory belts and pulleys last replaced? Double check the tightness of the belt to the alternator and the ps pump. They're two different belts.
 

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2006 Outback 2.5i Auto
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Might be worth replacing the O-ring on the top of the pump, could be shrinking when it's cold and letting some air in and causing the pump to cavitate a bit. It's under $5 and takes two minutes to change, and if it hasn't already started leaking it will. #JustSubaruThings ;)
It's almost exactly equivalent to a 1/2" ID, 5/8" OD, 1/16" wall o-ring. 65¢ at my local Ace hardware. You need a 10mm wrench to get the top hose off, and some towels handy to catch fluid until you lift the hose high enough. You might have to dig the old o-ring out of the inlet with a screwdriver. This completely fixed the whine on mine after a driving session turning lock to lock to get the air trapped in the steering rack out.

I didn't get any bubbles for the first two winters I had the car, I just had the whine on mornings below 10F (which aren't common here, although we're going to -10F tonight and tomorrow), with no real signs in the PS fluid reservoir, and it was modulated by throttle and reduced/changed by turning the steering. Then this year I've had the PS fluid reservoir spewing fluid as it frothed up and expanded due to the air in it. The o-ring was hard when I removed it.

Even if it's not the PS pump, eliminating that whine/possible cause will help with the diagnosis.

After that, I guess it could possibly be timing belt pulley or alternator bearings not liking the cold. You can pull the alternator/PS belts and start the engine to eliminate the alternator and PS pump in turn.
 

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Discussion Starter #6
Wow, thanks everybody. The weather this weekend is expected to be balmy (upper 20's) so I'll have a look at these things then:

1. PS reservoir suction hose/clamp tightness. Maybe change clamp, then bleed.
2. Replace O-ring at the top of the PS pump. (Thanks for the dimensions!)
3. Check tightness of belts to the alternator and PS pump.

Overall, I am getting the vibe that this is not a threatening situation, just an annoyance, which is good.
 

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2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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26,305 Posts
minor adjustment of the accessory belt on the power steering is typical for cold weather. H6 got the self tentioning type that all subarus should have had.

a couple years ago on my H4 I had new accessory belts that started to make a lot of noise on very cold days at start up, and even more from turning the wheel after cold start up (like to back up and turn around out of a garage or parking spot),

I could adjust away 50% of that noise myself but had to take it to a pro mechanic to wiggle out the rest of the noise.

today when its below 10F that same belt makes a little extra whine until the engine warms up within 3 miles of driving slow.
 

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2009 OB 2.5i 4EAT
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I'd follow eagleeye's advice. If it was PS, you'd see bubbles while idling or if it was really bad, foaming. If you do go ahead and replace the o-ring, make sure you bleed air out of the system like Evil Soob described... lots of guides skip it but it's critical.
 
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