New power steering pump high-pitched noise - follows RPM

[BPN]

Hi everyone,

My Camaro had a leak near the return line of the power steering pump. The alternator underneath it was quite greasy from all the fluid that had been leaking. Guess I missed that when purchasing the car... Anyway, I decided to replace it.

I ordered a new pump and tried to find out what fluid to put it. It's a 2010 2SS with the L99 engine, so it should be Dexron VI ATF according the Haynes. However, the fluid in the reservoir didn't look or smell like ATF, it was a clear substance. So, after replacing the pump, I decided to top it off with power steering fluid. Since the fluid mentioned in the Haynes manual (GM part no. 88901975) didn't seem to be available anywhere, I went to a shop here in the Netherlands that specialises in US cars. They sold me AC Delco 10-5073 19329448 fluid, telling me that should work just fine for my Camaro.

After removing the old pump, I cleaned everything (including the alternator) off with some brake cleaner sprayed on a clean rag. Then I installed the new pump, lifted the front wheels, turned the steering wheel left and right (lock to lock) completely for about 15 times with the engine off and the cap off the reservoir, and started the car, I heard the steering pump whine a little. I turned the wheel left and right about 15 times more with the engine running (cap still off the reservoir, of course). Then I waited for any visible air bubbles to disappear from the reservoir. Still a whining noise. I revved a bit and could tell this new whining sound follows along with the engine RPM. At about 3000-4000 rpm it became a horrible high-pitched whine, almost like a supercharger. Interestingly, the power steering itself works just fine in spite of this noise.

So now I'm stuck on what could this be... Is there somehow more air in the system that needs bleeding? I've tried steering lock to lock several time more, to no avail. The belt is new, so that shouldn't be it (it doesn't quite sound like a slipping belt to me either). Using a long metal bar pressed against the metal pump housing and then the alternator housing (as a stethoscope) I can tell this noise seems to be coming from the pump and not the alternator. But the pump and even the pulley are brand new and no more leaks are present as far as I can tell. Could the fluid itself be the problem, being the wrong kind?

Do you all have any advice, tips, help and/or possible solutions? It's driving me crazy!

[gtstorey]

Even new parts can be bad. Don't think its the fluid.

[BPN]

Originally Posted by gtstorey

Even new parts can be bad. Don't think its the fluid.

That's what I thought, too. And I got so fed up with the issue, I ordered ANOTHER new pump, flushed the system entirely, changed the fluid over to the Haynes prescribed Dexron VI ATF (using said ATF to flush the system as well) bled the system with the front raised and engine off until not a single bubble was visible anymore... and the problem is still there!! Although the power steering itself is now smoother and lighter than ever before...

Right now I'm noticing tiny bubbles keep appearing in the reservoir. This is after a 30 minute drive. I've checked all connections and hoses and can't find any leaks at all. I've got the front raised again, bled the system some more both with the engine off and later with it on, and decided to just leave it with the reservoir cap off until all bubbles disappear. At least the fluid keeps looking like clean, unpolluted ATF, so the flush was succesful...

All things considered, I think the problem is air in the fluid... question is: is it coming in through a leak that I can't find, or is this car just really hard to bleed properly? It does have the power steering cooler as part of the condensor, maybe that complicates things? Makes it harder to bleed?

Anyone who knows the solution to this puzzle will be my hero

[gtstorey]

I'm not sure that engine off is the correct bleed procedure, the older vehicles that I changed had the engine running to bleed. I'll try and check the factory service manual this evening and see what the oem says about bleeding.

[BPN]

Originally Posted by gtstorey

I'm not sure that engine off is the correct bleed procedure, the older vehicles that I changed had the engine running to bleed. I'll try and check the factory service manual this evening and see what the oem says about bleeding.

Well I've tried bleeding it with the engine off and the front wheels raised first, and then started the engine and bled a whole lot more. I figure the air should've come out by now, but nope... even after a night of sitting with the cap off the reservoir, the next morning there are still tiny bubbles in there... kinda like a soft drink. Still no sign of any leakages, but the level in the reservoir is dropping a bit. Soooo... maybe this is just a matter of playing the long game?

[gtstorey]

Sorry, didn't get a chance to check the service manual last night. Hopefully tonight.

[BPN]

So today I tried vacuum bleeding the system using a manual vacuum pump. Front wheels off the ground... again... and tried several methods. First, applied 15-20 inch of Hg and let it sit for 5 min. It holds this vacuum reasonably well, but not perfectly. In these 5 minutes the vacuum drops about 1 inch of Hg.

Then I applied this vacuum again and, with the engine off, steered lock-to-lock for many, many times again. Removed vacuum and let it sit for a bit. I still see tiny bubbles in the fluid and the pump whine noise is still there when I start the car. Still no visible leaks anywhere.

I'm running out of ideas. Maybe I need to pull the front bumper off to properly inspect the condenser with the fluid cooler in there, see if there's a small leak there...

[gtstorey]

Sorry, still didn't get a chance to check the manual for bleed procedure.

Have you tried driving it and seeing what it feels like?

[BPN]

Originally Posted by gtstorey

Sorry, still didn't get a chance to check the manual for bleed procedure.

Have you tried driving it and seeing what it feels like?

Yes. It feels fine. But it sounds terrible.
Trying to find replacement return lines, as I'm suspecting a leak that isn't obvious to the eye, but still causing my problems. Already found one from the rack to the cooler, article number 92249335. But the one from the cooler to the reservoir (article number 92249334) is out of stock/discontinued everywhere I look

[gtstorey]

If no sign of a fluid coming out, I doubt you have enough air entering the system to cause a problem.

I took pictures of the service manual bleeding procedure as well as the diagnostic steps, but it looks like I can no longer upload from my computer at work. I'll try and upload from home this evening.

[BPN]

Another update: I have replaced every single hose and every single clamp (for a worm wheel screw type). The short hose/line/hose part (art no 92249334) from the cooler exit to the reservoir I replaced with a single piece of 3/8" power steering hose. Works and fits just fine, no leaks, bled the system thoroughly again with the ol' "steer left-to-right and back many many times" method... But still there's air AND noise!

I'm at a loss here. new pump, new hoses, new clamps, flushed all the fluid, made sure it's now Dexron VI as prescribed... still this problem.

Does anyone have any suggestions?

[gtstorey]

Let’s see if this will upload

[George-CZ]

I wonder why you changed the whole pump instead of just the return hose when it worked well.
...or is the hose an integral part of the pump?

Anyway, if there is no leakage, it is strange that you have air in the system.

When it comes to noise, it's hard to diagnose anything without video.
But don't have greasy pulleys or belts that could slip?

[BPN]

Originally Posted by gtstorey

Let’s see if this will upload

Well that procedure contains some things that are new to me... like filling the reservoir up all the way to the bottom of the filler neck before beginning the bleeding process, for example. Or holding the steering wheel against the stops for 5 seconds with engine off and 2 seconds with engine on. Also, it prescribes using a vacuum of 15 inch of mercury during the initial bleeding without running the engine. It's quite different from the procedure in Haynes and the several youtube videos I've seen.

Where'd you get this service manual from?