Please help; Cold start groan/whine that's getting worse

[Glennda5id]

I bought the replacement bypass valve. Just picked it up yesterday. In the middle of swapping the trans on my legacy. Will most likky get it in this weekend.

[e39dinan]

Parked in the garage last night so it was about 10 - 12 degrees warmer. The whine was much quieter. This leads me to believe it's air seeping in past that o-ring. Going to park it outside tonight and start it up tomorrow, then check the PS pump tank for frothing. If present, I'll replace that and the relief valve mentioned. Does anyone have a source for the o-ring? Can't find the answer through the search engine. Thx.

[Glennda5id]

Sorry for the slow update.

Let me give an overview of my power steering problems and final resolution

Over the last year or so I have been suffering from noise from the PS pump and decreased power assist. Mostly noticeable when doing slow maneuvering in parking lots.
I have no leaks.

I did the following things.

Flushed fluid
Replaced suction hose o-ring
Replaced suction hose with 5/8" fuel hose.
Inspected return line to canister.
Inspected canister for cracks.

At this point I had made no improvement. There are many posts in other subaru forums about resealing the pump. The process involves tearing down the pump and replacing all of the seals. This seems to be a good fix for the folks who have done it. That being said, the pump used for the H6 cars is vastly different from other Subaru's. Its actually simpler in design. I took on this task and resealed my pump. This did not make an improvement.

This leads me to the TSB about the pressure releif valve. I bought that and installed it. No improvement...grrrr.

Part of the reason that I did this round about approach is that its really hard to source a rebuilt pump for these cars. I also don't trust the rebuilt parts but the new part is over $400. I kept hoping I could fix this on my own.

Long story short, I bought a rebuilt pump from Autozone. It is rebuilt by Atsco. It has a lifetime warranty. I installed my shiny new pressure relief valve in my rebuilt pump and I am golden now.

Long story short. I would replace the suction hose and suction hose oring. If that does not fix your problems I would replace the pump. I think the TSB really only covers at steering lock whining noise and so I would not mess with the pressure relief valve.

The part number for the oring for the H6 pump is 34439AE020

[1 Lucky Texan]

wow - you really stuck with it!

glad it's fixed but, kinda sucks you had to go thru all that to fix it.

I guess we don't know what was wrong with the old pump huh?

[Glennda5id]

Not knowing what was actually wrong was what drew this out as well. I wasn't 100% certain it was the pump, in which case replacing the pump might have been a waste. To diagnose a pump I need to measure the pressure at the output which I am not set up to do.

I'm fairly certain that the pump had worn out, ie the vanes in the pump or the bore needed to be replaced. When I disassembled it everything 'looked' okay but I don't have the specs, nor the tools to measure the internals of the pump.