New PS reservoir and pump, still has a low hum/moan

I have seen several posts about this but haven't found one yet with exactly my situation. Most solved the issue either by cleaning the screen or replacing the reservoir and/or the pump. First I flushed the system and still had the sound. Then I installed a brand new reservoir and still had the sound. Then I replaced the pump and still have the sound. The parts are brand new OEM Toyota from the dealer. So I have a brand new OEM steering pump/reservoir flushed and topped of with fresh ATF. It's not really hard to steer but maybe a little firmer than before but honestly I'm not even positive on that. I'm wondering if I'm imagining the firmer feel because I hear the sound. When I come to a stop in drive (automatic) it makes the sound. If I shift to park or neutral the slight increase of idle RPM makes it go away or lessen quite a bit. And yes, it makes this sound after everything is fully warmed up.

Does anyone know if the steering rack slowly going bad can make this sound before there are any significant steering symptoms? Maybe a restriction somewhere in the steering unit?

 

Any leaking?

Air completely out of your system?

Cavitating?

 

How long have you had it back together? Some times it will take some time for all the small bubbles to work out of the system.

 

The new parts have been in for over a month but probably have only driven about 220-250 miles. I would think that would have gotten all the air out but I guess it's possible.

 

No leaking that I've noticed. I'll probably give it a good look over again to make sure.

 

As mentioned, maybe air is still in there.

Did you lift the front end and turn from lock to lock?

When removing the cap, is it foamy or clear?

 

I lifted and turned lock to lock when I flushed but not after the new pump. I could try it again but I know I have had it lock to lock turning while driving since new parts installed though. And I would think over 200 miles of short distance drives with lots if turns would do it but maybe I'm wrong.

No foamy when I remove cap - just smooth, clean, red.

 

What type and brand ATF?

 

It could be the a/c idler pully making noise also. Loosen the a/c belt and see if sound changes.

 

This

 

Did you flush using the Timmy’s method ?

 

No. I did it with the engine off. Lifted front of truck, return line routed into a jug, constantly adding new fluid to the reservoir while turning wheel back and forth lock to lock until clean red fluid coming out of the return line into the jug.

 

This is the right way to do it.

 

It’s basically that. How’s the condition of your rack ?

 

I'll check this out when I can get the rest of the snow off and bring it in the garage. Thanks for the suggestion.

 

I think pretty good just but I'll get a closer look at it when I bring it in my garage. Maybe tomorrow. Not sure how old it is or if it is OEM. The truck had somewhere around 150k miles when I bought it and it's at about 201k now.

 

Thanks for the suggestions guys. I'll let you know what comes of it.

 

Alternator.

 

It sure doesn't sound like it but I'll give it a good listen again tomorrow and focus in on other areas.

 

Low hum, fluctuation in sound at idle when power windows are operated? ..

I had the same situation as you, use a stethoscope and check it out as an option

could be the rack or a steering line also., Check those.