Power Steering Flush & Reservoir Replacement - BMW M5 Forum and M6 Forums
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post #1 of 27 Old 2nd September 2010, 06:03 PM Thread Starter
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Power Steering Flush & Reservoir Replacement

Ok, so maybe this is overkill, but I was on vacation this week and decided to take care of some DIYs on the car. My power steering had been making some noise at lower speeds and there was a small leak at the reservoir (probably a bad o-ring). I decided to go ahead and replace the reservoir since the part was relatively cheap and I believe it has a non-replaceable filter in it. I also decided to go ahead and do a full flush of the system since the fluid looked like coffee. Again, this may be over-kill, but here is what I did along with a few photos. This isn't hard, but as with anything proceed at your own risk:

Parts required:
- Plastic bucket, bottle or some other disposable item that can hold 2-3 quarts of ATF and you don't mind drilling a hole in.
- 5' of 3/8 inside diameter hose
- 5' of 5/8 inside diameter hose
- 3/8" brass or plastic barb (used to join two sections of hose - i got these at home depot for like $1.50 each)
- 5/8" brass or plastic barb
- 5/8" brass or plastic tap (has a thread on one side and a barb on the other to connect the bucket to the hose)
- 2 small hose clamps (that can fit over the 3/8 line)
- 2 medium hose clamps (that can fit over the 5/8 line)
- Turkey baster
- Plastic cups or something else to catch ATF that leaks as you remove hoses
- disposable bottle to catch old fluid - I used an empty washer fluid bottle

Important Notes:
-You can use either ATF or Pentosin CHF 11S
-Fluid is sucked out very fast use a Minimum of 5 Liters in the Bucket & Very fast steering
-Keep 0.5 Liter for topping up


1. Remove the air filter box, top and bottom sections. Clips on top and next to mafs and then one band clamp at bottom for air inlet hose. Mine was stuck pretty good, but a few good pulls and it came loose. You may be able to get to the resevoir without removing, but it onlly takes a couple minutes and extra space is well worth it.

2. Use the turkey baster to suction out as much of the fluid from the resevoir as possible.

3. Remove the 3 10mm bolts holding the resevoir in place. 2 attach the resevoir to the car, 1 holds the clamp that keeps the resevoir in place.

4. With reservoir now free, hold a cup under it and tip on its side to drain out as much remaining fluid as possible.

5. Remove band clamps from suction (larger hose) and return lines (smaller hose). My car had the crush type clamps that were a ***** to get off. I basically cut them to get them off. I used the more typical screw type clamps as a replacement, much easier to adjust.

6. With clamps off, slowly work the suction and return hoses off of the reservoir - have plenty of shop towels ready to catch any spills. Takes a little effort, but they come off with hand pressure only, just be patient so you don't make a huge mess. Set reservoir aside or dispose if you are replacing.

7. Hold a cup under each hose and bend down to drain out more fluid.

8. Now you can attach the barbs and new section of hose to each of the suction and return hoses. I used clamps to make sure the hoses wouldn't come off during the flush.

9. I drilled a 3/4" hole in the bottom of a cheap plastic bucket and screwed in the barb with the threads (it is just tight enough that the ATF didn't leak out. I then attached the 5/8 hose between the bucket and the SUCTION hose (the LARGER of the two). Don't screw this part up or you'll have a big mess. I attached the 3/8 hose to the return line and put the other end in the washer fluid bottle to catch the old fluid.

10. Fill the bucket with 2 quarts of ATF. I used mobil 1 synth. Hold the bucket at about chest hight and allow the fluid to fill the hose down to the suction hose. You should start to see old fluid come out of the return line due to the pressure.

11. I then had a friend crank the engine (make sure you don't have any tools or towels near the fan, etc) and then turn the wheels left and right. Only took about 10 seconds to completely flush out the old fluid and start running bright red (see the contrast in the color in the picture below).

12. Carefully remove each fill hose from the suction and return lines and cover the end with your finger to keep any excess fluid from dumping all over your engine.

13. Attach the reservoir (impossible to mess up the connections since the pipes are sized to fit the two hoses) and tighten new band clamps. Reinstall the reservoir clamp and 3 10mm bolts holding it in place.

14. Top up reservoir and check for leaks. I ran the car for a few min, then let sit for 1 hr then topped up.

No leaks and the noise is gone. Again, there may be easier ways of doing this, but given how nasty the old fluid looked, I'm glad I flushed all that out.
Attached Thumbnails
IMG_2082.JPG   IMG_2088.JPG   IMG_2089.JPG   IMG_2090.JPG   IMG_2091.JPG  

Last edited by JohnAnthony; 13th June 2013 at 11:11 PM.
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post #2 of 27 Old 13th September 2010, 01:17 AM
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Did this yesterday. I wanted to replace my old leaking, 'reservoir to pump' pipe and flushed out the old stuff whilst I was at it.

It's nice to know that it's all clean and fresh in there now.

It's also pretty amazing how quickly the fluid is pumped though once the engine is running, only a handful of seconds is required (and very quick steering by your assistant).

Thanks for the clear 'how to.'
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post #3 of 27 Old 13th September 2010, 02:32 AM
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Arrow Well done!

I am the #1 fan of "overkill", so I guess we are kindred spirits.
Nice job with pic's too.

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post #4 of 27 Old 13th September 2010, 03:48 PM Thread Starter
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Thanks for feedback, but l just learned a lesson...

Well live and learn from this one. I took the belly pan off this weekend to clean it up and just poke around to see if anything was wrong. One thing that I noticed was the power steering suction hose is weeping where it is clamped to the power steering pump itself. No leaks at the new resevoir I installed, but I should have checked the hose at the other end when I had it all apart the first time. Its not bad, but will have to be changed out. I wish I had spent the extra 10 min to take the pan off when I first did this DIY so I wouldn't have to drain it again. At least I have all the parts ready.
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post #5 of 27 Old 13th September 2010, 04:00 PM
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You did a good job!! also you could change the PSF every time you do the engine oil change. It takes a few minuets to drain the reservoir and to fill it up again. This way the fluid will stay clean.
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post #6 of 27 Old 14th October 2010, 05:59 AM
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Did this last weekend, was experiencing loss of boost during low speed corners. Seems to be OK now.
I did use 3 quarts - 2 just didn't seem enough to get all the crap out of the system. I'm at 92K miles, original fluid.
By the way, replaced the leaking return hose, the reservoir (the fluid was so dirty that I didn't want to keep the non-removable filter) and got rid of the crush clamps while I was at it.
Once the air got out of the system, noise disappeared, boost is back to normal.
Nice job of the how to - thanks for putting it together.

Last edited by kjbruckner; 14th October 2010 at 06:02 AM.
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post #7 of 27 Old 14th October 2010, 03:12 PM Thread Starter
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No prob, glad it helped

I had similar noise, which the flush seems to have cured. I'm in the process of replacing pretty much all the oil hoses and vaccum lines, along with engine mounts. Will post some thoughts when I finish this up this weekend (I hope).
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post #8 of 27 Old 19th May 2014, 11:12 AM
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What a sweet idea! Doing this in next 2 days.... jacking up the car is not my favorite.

Thank you!

Last edited by Terabass; 19th May 2014 at 11:13 AM.
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post #9 of 27 Old 20th May 2014, 11:30 PM
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aaand its DONE!

Worked like a charm! Best technique ever
I had 2 gallons of synthetic ATF in the bucket and it's about 20 seconds to run that through the system while turning wheels left/right.

My power steering fluid was pretty much clear to begin with, but its nice to know that all little gunk is flushed out.
I got some video which I will post later.
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Last edited by Terabass; 20th May 2014 at 11:35 PM.
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post #10 of 27 Old 21st May 2014, 01:20 AM
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