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NEED Idiot Proof Step by Step Power Steering Flush

E28 technical advice asked and given! Troubleshooting, modifications and more.
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gtivalencia34
Posts: 52
Joined: May 28, 2017 10:39 AM
Location: NC

NEED Idiot Proof Step by Step Power Steering Flush

Post by gtivalencia34 »

Hello All,

I went on all the threads and not yet I have seen a complete DIY for flushing the power steering fluid. Can someone please give me a step by step on how this is done.

Thank you.
waynet1
Posts: 2524
Joined: Jan 10, 2011 11:49 AM
Location: Port Charlotte,FL-Newport,RI

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by waynet1 »

Image
vinceg101
Posts: 4981
Joined: Jun 20, 2007 2:40 AM
Location: Los Angeles, CA

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by vinceg101 »

You're not likely to find a complete procedure for an E28 either. Part of the issue is that there are a multitude of various hoses, high pressure lines, reservoirs and other pieces of hardware the hydraulic fluid runs through and resides in.
Wayne's short but eloquent picture of the turkey baster (a really great tool BTW; every box needs one) is about all you can effectively use to evacuate the fluid from the main reservoir. Short of disconnecting and draining all the hoses and high pressure lines, removing both the Power Steering Pump and Main Steering Gearbox and draining them, replacing the Hydro-Accumulator Switch & Bomb, and don't forget the hard pipe cooling loop running up to the front grille, you're not going to replace all that fluid in one sitting. Truth is you will likely never get all of the fluid out of all those components.

The best you can do is suck out what is in the reservoir, refill, rinse and repeat several times. It's a pressurized system so pushing through new fluid several times is as about as effective a method as there is.
You're almost better off just replacing all those components; cleaner, more effective and resolves all those leaks in your driveway.
(Of course this is a heck of a project)
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by Mike W. »

It's like auto transmissions, a fluid change doesn't get nearly all the ATF out. But do it 3 or 4 times and you're up in the 90%+ range.

Personally I'd pull the hose from the reservoir to the pump and drain that, but the turkey baster is much cleaner.
vinceg101
Posts: 4981
Joined: Jun 20, 2007 2:40 AM
Location: Los Angeles, CA

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by vinceg101 »

Image

You just have to use a lot of towels; hydraulic fluid is extremely caustic and will eat & etch paint and finish off of anything it comes in contact with.

(See, even I have the same baster; I think the all come with a yellow top, must be an FDA thing)
a
Posts: 12473
Joined: Feb 12, 2006 12:00 PM
Location: Marshfield ,MA

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by a »

Yah ,its a messy job.Idiot proof? No guarantees, On a 528e. I used a short piece of hose with a bolt in it to plug the pump's gazinta. Then I put the return into a jug. I topped off the pump then started the engine. IIRC it worked sorta. The job needed better prior prep. Pita was , the job didn't fix the trouble. The fix was a freed up U-joint. :rofl:

PS. Despite all extra plumbing, the 535i shouldn't be too different , It is a series loop. Plug the return where it enters the pump after you empty it with the syringe. Make sure the return is secured to the jug. BTW all I ever used for PS fluid was ATF
LarryM
Posts: 1265
Joined: Feb 01, 2008 11:40 AM
Location: SoCal

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by LarryM »

I think so many of us have experienced power steering leaks to the degree that our P/S systems have been "flushed" from their original fluid anyway.
gtivalencia34
Posts: 52
Joined: May 28, 2017 10:39 AM
Location: NC

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by gtivalencia34 »

vinceg101 wrote:You're not likely to find a complete procedure for an E28 either. Part of the issue is that there are a multitude of various hoses, high pressure lines, reservoirs and other pieces of hardware the hydraulic fluid runs through and resides in.
Wayne's short but eloquent picture of the turkey baster (a really great tool BTW; every box needs one) is about all you can effectively use to evacuate the fluid from the main reservoir. Short of disconnecting and draining all the hoses and high pressure lines, removing both the Power Steering Pump and Main Steering Gearbox and draining them, replacing the Hydro-Accumulator Switch & Bomb, and don't forget the hard pipe cooling loop running up to the front grille, you're not going to replace all that fluid in one sitting. Truth is you will likely never get all of the fluid out of all those components.

The best you can do is suck out what is in the reservoir, refill, rinse and repeat several times. It's a pressurized system so pushing through new fluid several times is as about as effective a method as there is.
You're almost better off just replacing all those components; cleaner, more effective and resolves all those leaks in your driveway.
(Of course this is a heck of a project)

Thank you!!!
gtivalencia34
Posts: 52
Joined: May 28, 2017 10:39 AM
Location: NC

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by gtivalencia34 »

Mike W. wrote:It's like auto transmissions, a fluid change doesn't get nearly all the ATF out. But do it 3 or 4 times and you're up in the 90%+ range.

Personally I'd pull the hose from the reservoir to the pump and drain that, but the turkey baster is much cleaner.

Thank you!
gtivalencia34
Posts: 52
Joined: May 28, 2017 10:39 AM
Location: NC

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by gtivalencia34 »

Thank you All,

So now I found the actual problem and it's the POWER STEERING RACK. What do you guys recommend? replace it with a used unit or keep it dripping?
a
Posts: 12473
Joined: Feb 12, 2006 12:00 PM
Location: Marshfield ,MA

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by a »

The go fast guys will recommend an M 5 box, less turns. The cheap guys like me recommend a used box preferably from a 528e if they interchange,IDK
BRRV
Posts: 3160
Joined: Feb 12, 2006 12:00 PM
Location: Pensacola, Gulf of America

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by BRRV »

No "rack' on an E28. Recirculating ball with a steering box.
Kyle in NO
Posts: 17638
Joined: Feb 12, 2006 12:00 PM
Location: Nasty Orleans------> Batten-Rooehjch------>More Souther LA

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by Kyle in NO »

Crack the banjo bolt on the power steering pump to drain the system, its the lowest point. Change the filter element while you are in there. Refill reservoir with fresh ATF. If it's super dirty, you can do it more than once.
demetk
Posts: 8431
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by demetk »

gtivalencia34 wrote:What do you guys recommend? replace it with a used unit or keep it dripping?
If you stop topping it off, it will eventually stop dripping on it's own.
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by Mike W. »

a wrote:The cheap guys like me recommend a used box preferably from a 528e if they interchange,IDK
They do, I've done it, straight swap. I was bummed though that the low mileage eta box (110K) was just as sloppy as the 200K one it replaced. No clunk for a while at least though.
jimoreno
Posts: 1601
Joined: Aug 30, 2007 9:31 PM
Location: Land O Lakes, FL

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by jimoreno »

There is a drain plug at the bottom of the PS pump (at least in my M30) that I have used to drain the system. But if your steering box is leaking a replacement is the only way to stop that leak (or get the kit and re-seal it but if there are grooves in the shafts it will be useless).

Good luck!
jamracing
Posts: 5
Joined: Jan 08, 2025 2:25 PM
Location: Northbrook, IL

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by jamracing »

Speaking of draining the oil - i currently have the mineral oil running through the system - can i drain and fill with ATF several times without doing damage?
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by Mike W. »

jamracing wrote: Feb 26, 2025 2:10 PM Speaking of draining the oil - i currently have the mineral oil running through the system - can i drain and fill with ATF several times without doing damage?
I would say yes, and the sooner the better. Although mineral oil is typically a light petroleum oil anyway so it's also possible no harm will come of it. Still, better to have the right stuff in there. Fortunately unlike an Auto box the P/S system doesn't hold a whole lot so it's not like buying gallons and gallons.
jamracing
Posts: 5
Joined: Jan 08, 2025 2:25 PM
Location: Northbrook, IL

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by jamracing »

Mike W." wrote: Feb 26, 2025 3:38 PM
jamracing wrote: Feb 26, 2025 2:10 PM Speaking of draining the oil - i currently have the mineral oil running through the system - can i drain and fill with ATF several times without doing damage?
I would say yes, and the sooner the better. Although mineral oil is typically a light petroleum oil anyway so it's also possible no harm will come of it. Still, better to have the right stuff in there. Fortunately unlike an Auto box the P/S system doesn't hold a whole lot so it's not like buying gallons and gallons.
Thanks Mike - i also have the pump rebuild kit so might just get both tasks completed at the same time. The whole side of the engine bay is oily, so will also change out the crush washers on the pipes, hopefully that and the rebuild will solve that
Mike W.
Posts: 27514
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: NEED Idiot Proof Step by Step Power Steering Flush

Post by Mike W. »

jamracing wrote: Feb 26, 2025 3:48 PM
Thanks Mike - i also have the pump rebuild kit so might just get both tasks completed at the same time. The whole side of the engine bay is oily, so will also change out the crush washers on the pipes, hopefully that and the rebuild will solve that
In that case, hope the brake booster isn't leaking. It can make a real mess out of things and is in that same P/S hydraulic loop, assuming it's an M30 car. Not that it's in insurmountable job, just kind of a PITA.
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