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Discussion Starter #1
2006 330ci Coupe. 221,000 miles.

Sudden low pitch groan started in the power steering while I was idling for 15 minutes the morning after an 800 mile drive. Groan is worse when turning the wheel at lower speeds. Driving straight at highway speeds almost completely gone.

Checked the fluid level and it look good. (I replaced the PS reservoir and its 2 hoses about 6 months ago.)

The power steering pump and the pressure hoses are original to the car so I decided to replace the pump.
Did not change the noise. Drained the PS reservoir and saw some small black debris which appeared to be pieces of one of the hoses which could be deteriorating from the inside. So I replaced the long double wrap pressure hose (32416774215) that goes from the pump to the steering rack. No change in the noise.

I have checked the fluid and bled the system a couple of times. The noise is possibly worse now that I put the new pressure hose on. The other pressure hose that returns from the pump to the rack is on order. These were all original to the car so I'm not concerned about "throwing" these parts at the problem. Of course if I replace the 2 pressure hoses, the pump and the reservoir is new with new hoses and I don't fix the problem then I will be at a loss for what's going on.

As far as I know the things that can cause PS noise like this are low fluid, bad pump, blockage in the system etc.

Any ideas on how to diagnose this better? Or similar stories?

Thanks in advance for your time and help.

Dave
 

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You should consider changing the power steering fluid reservoir. It has a filter at the bottom. It may be clogged. The factory reservoir is made by ZF. Buy a ZF reservoir at FCPEuro. Be advised that all E46s sold in the US use automatic transmission fluid for power steering fluid. The factory put Dexron3 in the power steering system.

You should also consider a power steering fluid flush. What you’ll need:
  • 4 quarts of Dexron3
  • 2 quarts of either Dexron6 or Redline D4ATF (I prefer Redline)
  • 4 feet of heater hose
  • large container (2 gallons) to catch the fluid
  • an assistant.
Procedure:
  • install the new ZF power steering fluid reservoir
  • do not install the hose that runs from the power steering fluid cooler to the reservoir
  • leave the cap on the reservoir nipple where the aforementioned hose attaches
  • connect the heater hose to the aforementioned hose
  • put the other end of the heater hose in the container, making sure it’s secured to the container or else you’ll have power steering fluid everywhere!
  • OPEN ALL FLUID CONTAINERS and have them readily available!
  • fill the reservoir with Dexron3
  • have a container of Dexron3 in one of your hands
  • have your assistant start the engine and rotate the steering wheel from full left to full right to full left repeatedly
  • add fluid QUICKLY as you do not want the pump to run without fluid
  • switch to Dexron6 or Redline when you’ve used up the Dexron3
  • shut off the engine when you’ve got about 1/2 quart of Dexron6 or Redline left
  • remove the fluid in the reservoir
  • connect the aforementioned hose to the outer nipple of the reservoir
  • top off the power steering fluid
  • start the engine and add fluid as necessary.
 

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Agree with the above advice, plus a comment and also a bizarre cure that has worked.

First, most/all factory PS hoses have a noise-reducing engineered baffle in them to eliminate the natural sounds of a hydraulic pump assembly. If you have a hose made at a local hydraulic hose shop, they can often reuse this part as well as obviously the connections on each end. If you buy an aftermarket hose it will not likely have this feature. From then on you will have these noises - perfectly acceptable on a bulldozer, not so on a consumer automobile. There may also be an internal screen in the pump that's partly blocked by those black bits, causing increased suction and cavitation noises.

Second, the bizarre cure. My brother in law's LandCruiser has 325k on it and a couple years back its PS pump began groaning. He didn't want to spend the big bucks to replace it, so I put a capful of Bounce fabric softener in it after hearing this from someone I trusted. Boom. Silent. Every 6 months or so it would need a bit more and then we'd simply evacuate the reservoir and put fresh fluid in it to ensure we kept a good ratio of fresh fluid. The sound you're often hearing in a hydraulic pump is simple cavitation, which is the violent collapse of tiny bubbles. I believe the fabric softener somehow prevents the formation of the bubbles, or reduces the fluid's surface tension enough that they collapse at much lower pressures. YMMV.
 

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Discussion Starter #6
Ok. Thanks to all for this great guidance! I really appreciate the help.

I will definitely flush the system. I am really curious about the fabric softener trick.

Curious, what could be causing the bubbles/cavitation? Just the blockage? Or contaminated fluid?
 

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Ok. Problem solved. It turned out to be the Power Steering Suction Hose - 32416750155 which runs from the reservoir to the pump. The inside of the hose was collapsed.

I was baffled because I just replaced this hose in March. Hardly any miles on it. The hose came from FCP Euro in their reservoir replacement kit. Just went back to read reviews of this hose (made by Rein) and several reviews mentioned the exact same problem. New hose, fails, owner confused about where the problem lies.

When I took off the reservoir trying to find the problem I saw the top of that hose and it had fluid in it and looked to be fine. Until today I hadn't yet taken that hose completely off to check it because I assumed the new hose would not likely be the problem. I quickly suspected the 2 pressure hoses that are 14 years and 220k miles old.

Anyway, thanks for everyone's help. Reminds me of an old adage that I have been told several times and did not heed its wise advice: Any part can fail at any time, even new ones.

So. Be careful with Rein hoses and pull everything completely off and check it all even if it's new.

Thanks,
Dave
 

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Ok. Problem solved. It turned out to be the Power Steering Suction Hose - 32416750155 which runs from the reservoir to the pump. The inside of the hose was collapsed.

I was baffled because I just replaced this hose in March. Hardly any miles on it. The hose came from FCP Euro in their reservoir replacement kit. Just went back to read reviews of this hose (made by Rein) and several reviews mentioned the exact same problem. New hose, fails, owner confused about where the problem lies.

When I took off the reservoir trying to find the problem I saw the top of that hose and it had fluid in it and looked to be fine. Until today I hadn't yet taken that hose completely off to check it because I assumed the new hose would not likely be the problem. I quickly suspected the 2 pressure hoses that are 14 years and 220k miles old.

Anyway, thanks for everyone's help. Reminds me of an old adage that I have been told several times and did not heed its wise advice: Any part can fail at any time, even new ones.

So. Be careful with Rein hoses and pull everything completely off and check it all even if it's new.

Thanks,
Dave
The good part is that FCP will replace part of a kit.
 

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I just had the same thing happen to me at 8 months on the same shitty Rein hose from that kit. I ordered the Genuine BMW hose from FCP and requested a warranty return on this Rein trash, so I'm out another $35 for the cost difference and postage. I'm really just upset about the hours wasted trying to figure this out and weeks spent with the car down.
 

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hello,
If you hear a whining noise while turning the wheel of your vehicle, something is wrong with your power steering system. It could be a leak in the power steering pump or the fluid level could be low. ... Either way, the power steering pump needs to be looked at and potentially replaced by a professional. FREEMOVIESDOWNLOAD
regards
 

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Discussion Starter #15
Thanks for coming back with the solution. We’ll all now be wary of new PS hoses.
How exactly did you determine that the hose had internally collapsed?
I took off all the hoses one by one and inspected them and blew compressed air thru them to make sure there wasn't any blockages. When I went to blow air thru this hose, didn't go thru. Squeezing the hose it felt like it was clogged up. Used a long screw driver to confirm that the hose was blocked by the inner lining.
 

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hello,
If you hear a whining noise while turning the wheel of your vehicle, something is wrong with your power steering system. It could be a leak in the power steering pump or the fluid level could be low. ... Either way, the power steering pump needs to be looked at and potentially replaced by a professional.
regards
Lol. Did you even read the thread?
 

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Thanks for coming back with the solution. We’ll all now be wary of new PS hoses.
How exactly did you determine that the hose had internally collapsed?
I saw that OP used compressed air so I'll share my path to the root cause:

November 2019: Replaced the steering rack and swapped in the PS hose kit from FCP euro while I was there.

July 2020: Started the car one day and the idle felt...heavy? Went to drive away and the PS pump was moaning (loudly) when I turned the wheel. Checked the fluid and it was fine, but didn't appear to be flowing. Limped the car home and let it sit while I did some research. Came across one thread that mentioned the collapsed suction hose, so I removed the air box, checked out the hose (it looked ok), started the car, and saw that the hose immediately collapsed (went flat in a few areas).

I have two e46's so I swapped a good hose over from the project car, refilled the reservoir, and fired it up. Perfect.

F that janky Rein hose.
 

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Discussion Starter #20
I saw that OP used compressed air so I'll share my path to the root cause:

November 2019: Replaced the steering rack and swapped in the PS hose kit from FCP euro while I was there.

July 2020: Started the car one day and the idle felt...heavy? Went to drive away and the PS pump was moaning (loudly) when I turned the wheel. Checked the fluid and it was fine, but didn't appear to be flowing. Limped the car home and let it sit while I did some research. Came across one thread that mentioned the collapsed suction hose, so I removed the air box, checked out the hose (it looked ok), started the car, and saw that the hose immediately collapsed (went flat in a few areas).

I have two e46's so I swapped a good hose over from the project car, refilled the reservoir, and fired it up. Perfect.

F that janky Rein hose.
Ok. So sounds like the real solution is that I need to get another E46....
 
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