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NEED Idiot Proof Step by Step Power Steering Flush
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- Posts: 52
- Joined: May 28, 2017 10:39 AM
- Location: NC
NEED Idiot Proof Step by Step Power Steering Flush
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.
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.
Re: NEED Idiot Proof Step by Step Power Steering Flush
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)
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)
Re: NEED Idiot Proof Step by Step Power Steering Flush
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.
Personally I'd pull the hose from the reservoir to the pump and drain that, but the turkey baster is much cleaner.
Re: NEED Idiot Proof Step by Step Power Steering Flush

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)
Re: NEED Idiot Proof Step by Step Power Steering Flush
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. 
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

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
Re: NEED Idiot Proof Step by Step Power Steering Flush
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.
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- Posts: 52
- Joined: May 28, 2017 10:39 AM
- Location: NC
Re: NEED Idiot Proof Step by Step Power Steering Flush
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!!!
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- Posts: 52
- Joined: May 28, 2017 10:39 AM
- Location: NC
Re: NEED Idiot Proof Step by Step Power Steering Flush
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!
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- Posts: 52
- Joined: May 28, 2017 10:39 AM
- Location: NC
Re: NEED Idiot Proof Step by Step Power Steering Flush
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?
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?
Re: NEED Idiot Proof Step by Step Power Steering Flush
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
Re: NEED Idiot Proof Step by Step Power Steering Flush
No "rack' on an E28. Recirculating ball with a steering box.
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- 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
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.
Re: NEED Idiot Proof Step by Step Power Steering Flush
If you stop topping it off, it will eventually stop dripping on it's own.gtivalencia34 wrote:What do you guys recommend? replace it with a used unit or keep it dripping?
Re: NEED Idiot Proof Step by Step Power Steering Flush
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.a wrote:The cheap guys like me recommend a used box preferably from a 528e if they interchange,IDK
Re: NEED Idiot Proof Step by Step Power Steering Flush
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!
Good luck!
Re: NEED Idiot Proof Step by Step Power Steering Flush
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?
Re: NEED Idiot Proof Step by Step Power Steering Flush
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 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?
Re: NEED Idiot Proof Step by Step Power Steering Flush
Mike W." wrote: Feb 26, 2025 3:38 PMI 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 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?
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
Re: NEED Idiot Proof Step by Step Power Steering Flush
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.jamracing wrote: Feb 26, 2025 3:48 PMThanks 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