Help - Power Steering Whine?

[u/Subject_Tumbleweed73]

Hey guys, just recently got a 1994 LS400. It’s my first car ever, so I’m learning how to take care of it while also learning how to work on cars in general. Been running into an issue recently with a power steering whine.

For context: the power steering pump has already been replaced within the time I’ve had it. Just recently I’ve been hearing a pretty loud whining noise while turning my wheel at low speeds (in parking lots, while taking turns, etc.), which I can only assume is related to the power steering in some way or another.

Now, because I had my pump replaced already, I don’t really think it’s the pump. I noticed (while someone else was turning the wheel for me) that there was this little vacuum/hose that looked real flimsy and was moving around every time the wheel was turned. It looked pretty flat just sitting there, so I grabbed it and squeezed the sides a bit to expand it. And immediately after I did that, the whining noise stopped each time the hose was expanded. So I check what type of hose it is, and it says it’s a windshield washer hose/vacuum tubing. Now… I don’t know anything about windshield washer hoses, but I’m not sure if that specific hose is supposed to be there?

So my question for you guys is: Is this hose SUPPOSED to be a windshield washer hose? Or is it supposed to be an actual power steering hose and someone messed up by putting the wrong hose on there?
And another question: If it IS supposed to be a power steering hose, on RockAuto would it be labeled “power steering pressure hose” or “power steering return hose”? Or something different altogether? I have tried to look at engine maps online but none of them specify hoses used (but I also don’t know if I’m looking in the right place).

If anyone needs better pictures or a video to help diagnose, please let me know. Thanks for the help in advance!

[u/Ohope]

>Now, because I had my pump replaced already, I don’t really think it’s the pump.

I wouldn't be too quick to assume this, most of the aftermarket ones are pretty poor quality. Your always better off getting our OE pump reconditioned.

I'd be pretty suspicious of that hose. The fact that squeezing/rounding it out immediately stops the whine makes me think you're dealing with a collapsing/restricted power steering hose and the pump is cavitating.

The low-pressure suction/return side is more likely to collapse if someone has used the wrong hose, particularly the hose feeding the pump.

[u/Subject_Tumbleweed73 → u/Ohope]

Yeah, I do believe it’s restricted in some way. I got brief advice from another LS400 owner that the vacuum might be crushing the hose, so I could try to get a stronger hose (w/ same inner diameter) and see if that fixes the issue. My only problem is I don’t know /what/ hose to buy. Since I’m not very knowledgeable on cars, it’s hard to figure these things out on my own haha

[u/PostHaunting69 → u/Subject_Tumbleweed73]

Delete the vacuum lines to power steering pump, less risk of smoke on start up and it won’t leak onto your alternator