05 power steering/hydro noise

[Blue Tank]

Hi Guys
05 Burb, 4wd, 5.3 130k
A couple of months ago when it was really cold out one morning i fired up the burb and had a very loud p/s noise. It was real loud. I shut it off for a bit and fired it back up to find it was still there. I let it idle a bit and it sounded a little better, I had to go.
Some days the noise is better and the warmer weather seemed to help. Originally I thought there was probably some water in the fluid and it has frozen the bypass open, that's the sound it makes. It also shows up in the hydro boost when you press the brake pedal. Now that it's warmer that dream went away. When I checked the board I noticed that a couple of guys had a pin hole in the pressure lines. I checked and the pump to hydro line had that fine dust stuck to the covering. Ordered 2 new pressure lines, replaced them today and I think it sounds worse.
I watched the reservoir with the cap off and the truck running, the fluid still has small bubbles after bleeding it. After turning the wheels while up on a jack and then leaving them centered with the motor on it looks like its "simmering" in there. Not continuos but every few seconds decent size bubbles rise up thru the fluid. When you step on the brakes it like all hell breaks loose in the rez. If you touch the pressure lines it feels like they are vibrating at idle.
Any ideas?
thanks
Mark

[Blue Tank]

After I saw a few threads about the return lines being a possible cause I looked them over better. The ones from the oil cooler looked a little wet so I added a worm clamp to the worst one and it seemed to be a little better. The cooler had some decent rust on it so I ordered a new one and the one from the hydro to rez. Changed them last night and it's about the same thing. If I still had hair i'd pull it out. At this point I could have created a second problem from running the system with the original problem. I'm going to change the p/s pump next.
One question I have is about opening the rez. Every time I open it you get the sound of pressure or vac escaping. Does this say anything to you guys?

[mongocanfly]

Is the noise coming from the pump?
Maybe this'll help...
https://www.brakeandfrontend.com/ope...ssist-systems/

[Blue Tank]

Yes the noise is the pump itself, belt and pulley are good. That's a good link i'll read thru it tonite, thanks.
Maybe i'm wrong but I keep going back to it being a very cold day when it started. I'd take the bypass valve in the pump out to see if it's stuck but i'm afraid i'll damage the square o ring and then i'm poked. I would think that would be the only place in the pump itself that could cause bubbles/air. I'm thinking the cavitation caused by the fluid being forced thru the bypass orfice for an extended time.
It growls at idle now and increases if you touch the brakes or the wheel. Sometimes at low rpm the steering assist isn't there without a small increase in rpm. After the motor is shutdown it's a built up pressure when I remove the rez cap. If you watch the foamy fluid you'll see a good size bubble come up and the fluid level goes down a bit a few times.
I'm including as much as possible so when we figure it out the next guy has a good list.

[57taskforce]

When I added the hydraboost to my K20, I had to fill the reservoir with it running until the pump quieted down. It would foam the fluid and cavitate the pump really bad until I tried adding fluid with it running. After topping it off a couple times running it finally bled out and had been great since. If you don’t have a fluid level/air issue I would suspect the pump is on the way out.

[Bigdav160]

I had a terrible time getting the air out of my hydroboost conversion to my K20. Likely because of my lack of high mounted reservoir.

[Blue Tank]

57
That's interesting, I got the feeling there was some voodoo involved.
The new GM pump came in and I was flaming pretty quickly. The box had a nice hologram sticker on it assuring me that I had an official part...... made in China. Fool me once GM.
Anyhew when I tore in to I noticed more leakage and scuz around the bottom of the hydro and the bracket below it. I figured that as usual after buying one thing the actual problem would reveal itself. Put the new pump in and it was instantly quiet, both the p/s and brakes worked great. Hmmm.
After driving it for a bit I also noticed how the steering worked better than before. I guess the pump had been weak for awhile but still worked for the most part. I did notice that I cut the pressure hose o ring when I changed the hoses before.
Take aways
I guess this could have been trouble shot with a p/s pressure gauge thingy.
For some reason the cold weather made it pop.
Changing hoses/ cooler made it louder.
Both steering and brakes were affected at the same time.
Thanks for the replies.
Mark

[paul mora]

You were faced with a problem I see quite often. When you have air in the system you can usually get it out fairly easy. It’s solved quickly. Pumps that whine stay around and usually get louder as the rpms go up. You can play with it for days thinking you have air in the system change the pump and magic no more noise. There are exceptions. I once changed the pump had the same problem and it was a bad pump. I try to stay away from anything made in China