intermittent high-pitched whine, varies w/engine speed: PS pump?

Went on a long camping trip this weekend and on the way back I kept having an intermittent loud whine that seemed to vary with the engine speed, not the vehicle speed (it was even present when the truck was stopped and in park.) It did it when we left camp (everything cold) and eventually stopped on its own. It would periodically come back but never as loud as when it first started.

Since I've had transmission problems before (had the 4L60 rebuilt in 2016 after it failed on the way home from a camping trip) I assumed the sound was from the transmission, since it seemed to vary based on speed.

Then, this morning on the way to work it started making a really loud noise, again a high-pitched whine. I noticed the sound "spiked" when I turned the steering wheel sharply which now leads me to believe it might be the power steering pump.

Not sure if I can upload the video file of the noise but I'll try.

Anyone else have a similar problem?

Vehicle is a 2004 Suburban 1500 LT, 5.3, 4x4, with about 175,000 miles on it. Transmission was rebuilt at 150k by a reputable shop.

Thanks in advance for any advice or pointers!

EDIT: Can't seem to load the *.MOV file from my iPhone. Is there any other way to upload a video? File is 20mb if that makes a difference.

 

did ya check the p/s fluid level yet? look for leaks?

 

Checked it this morning but it was too dark to see the level. Will try again this afternoon (hoping the snow stops!)

If there are any leaks, they aren't hitting the ground. I'd see that in the driveway.

 

A-ha! Possible source of at least the noise I was getting when pulling the trailer.

Manual says this:

I think the PS noise is unrelated. It was really a completely different sound.

 

you can upload your video file to youtube and then copy and paste the link in a reply.
does it sound like a pulley? it is common for the ac tensioner pulley to make some noise especially when it is cold
you can test this theory by simply inserting a socket drive into the front of the ac tensioner pulley give it a twist and this will allow you to take the belt off, you can just leave it hanging it wont hurt anything to leave it dangling while running the vehicle. best to try it early in the morning before the first start because once it has warmed up they usually stop squeaking.

 

Well, the PS fluid reservoir was bone dry! Filled it to the "full cold" line and now it seems to be working fine.

No evidence of leaks, not sure how the fluid got out of there. Anyway, problem fixed, at least for now. No sign of any leaks but I haven't really closely examined the area with a flashlight yet.

 

p/s fluid dont burn off. so you have a leak. slow as it might be. you'll find a wet dirty greasy dirty line im sure. ( that dirty mess is the leak)

seen a few guys have the p/s cooler leak. if you got one its up front of the rad in the grill area driver side.

 

Yup, they're prone to leaking through the fins usually. Especially if you're in the rust belt.
Mine.

 

you will also want to check each side of the power steering unit where the tie rods go into the boot there is a seal in there on each side, my Silverado was literally pissing out fluid on one side when making a turn. of course it also left a obvious spot on the driveway as well. you can jack up the front end so both wheels are off the ground and start it up and turn your wheels all the way left & right and look under there and see if you see fluid coming out anywhere or just look for any obvious wet spots then look up or forward from there (a flashlight helps even if it is daytime)

 

I have the same problem in my 4 runner- to the letter. She was bone dry too! I dont know where the leak is because the driveway is clean.

Your're not alone man!