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DIY: Full power steering fluid flush

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    DIY: Full power steering fluid flush

    Background: I've seen a few people who subscribe to the "turkey baster" method of slowly refreshing the PS fluid in the reservoir by siphoning a bit out and replenishing it with fresh fluid. This is a very easy method as it can be done without taking anything apart. If you have a well maintained car this could be used to keep it in top shape. If your car wasn't reliably maintained, The problem is that any of the heavier contaminants tend to stay in the bottom of the system (reservoir is the highest point), including metal, etc.

    There are a lot of loops / connectors in the PS system so it is challenging to drain. I think I have found a method which is worth sharing that is pretty simple and gets almost all the fluid out of the lines.

    TOOLS:
    19mm socket
    22mm socket
    8mm socket
    Funnel
    Pliers
    Oil drain pan
    Brake vacuum pump with a 90 degree rubber nipple (pictured)

    PARTS:
    The factory oil for the M3 was a DEXRON-III ATF, however this specification was discontinued in 2011. DEXRON-VI is backwards compatible and I've been using it in my car with good results. You will need one quart.
    2x 32411093596 crush washer for 19mm banjo bolt
    2x 32411093597 crush washer for 22mm banjo bolt

    (optional): High pressure power steering line often leaks, good time to replace it: 32412283893
    (optional): if replacing high pressure line, 2x additional crush washers, 32411093597

    (optional): Ear clamp kit. You will need a 22-25MM ear clamp.
    (optional vs the ear clamp kit): worm gear clamp

    1.) Secure the car on jack stands

    2.) Pop the hood, locate the power steering reservoir.

    3.) Underneath the car, remove the black plastic belly pan

    4.) Locate the two banjo bolts which connect the hoses to your power steering rack. (pictured)

    5.) Get drain pan in place and loosen the 22mm banjo bolt. Fluid should start trickling down the rack near the green (or blue if you have comp pkg) tag. This is where you will want to place your drain pan.

    6.) After the fluid seems drained, fully remove the banjo bolt. Make sure to remove both crush washers (one on bolt side, one on rack side)

    7.) Get in your car. Put in the key so the steering lock is disabled (do not start the car), then fully turn the wheel left and right 3-5 times. When you are at full lock leave it there for about 10-20 seconds so the fluid can drain fully.

    8.) Remove the 19mm banjo bolt. Make sure you get both crush washers again as they can stick to the rack.

    9.) Navigate the hose out from behind the rack. Leave it dangling as the lowest point under your car so the fluid can drain out of it.

    10.) Find the hose that goes in to the back of your power steering pump. (pictured). Remove the BMW factory hose clamp (pictured) by prying on the green painted part with pliers. It should easily pop off.

    11.) Carefully slide the hose back until the fluid starts to trickle out.

    12.) After the fluid is drained, slide a new ear clamp on to the hose (or worm gear).

    13.) Re-clamp the hose (or tighten the worm gear)

    14.) Replace the 19mm banjo bolt with new crush washers. Order is rack-> crush washer -> hose -> other crush washer -> bolt. Torque to 35NM (25 lbs ft)

    15.) Go to the top of the car and remove the cap of the PS reservoir. Use a funnel to refill it to about 3/4 full.

    16.) Back under the car, grab the 22mm banjo hose and get it over the drain pan. Put the 90 degree vacuum bleeder nipple in to one side of the hose opening. Use your fingers to close the other side.

    17.) Put some vacuum in to the hose. You should be able to get fluid almost gushing out. This is from the reservoir to the cooling loop in front of the radiator. Keep pulling fluid until it turns a nice healthy red color.

    18.) Replace 22mm banjo bolt / hose with new crush washers. Order is rack-> crush washer -> hose -> other crush washer -> bolt. Torque to 40NM (30 lbs ft)

    19.) Replace belly pan.

    20.) Fill PS reservoir until it's on the 2nd mark on the PS dip stick (the higher, or more "full" of the lines)

    21.) With front of car still in the air, Start car. Steer left and right a few times. Stop car.

    22.) Refill PS reservoir to the 1st mark on the PS dip stick (lower line) if your car is cold. If you check again when it's warm / foam free it should be on the 2nd line.
    Last edited by Nuclear Rabbit; 09-02-2021, 05:34 PM.

    #2
    I recommend removing the filter box. Makes access to the reservoir a *lot* easier.
    It will also make cleaning all the leaked, gunked up with dirt PS fluid easier too.

    Comment


      #3
      Originally posted by Nuclear Rabbit View Post
      Background: I've seen a few people who subscribe to the "turkey baster" method of slowly refreshing the PS fluid in the reservoir by siphoning a bit out and replenishing it with fresh fluid. This is a very easy method as it can be done without taking anything apart. If you have a well maintained car this could be used to keep it in top shape. If your car wasn't reliably maintained, The problem is that any of the heavier contaminants tend to stay in the bottom of the system (reservoir is the highest point), including metal, etc.
      Very nice write-up; I was tempted to do the "incremental" replacement method, but I'd rather do it all at once. Does the process amount to "undo the hoses from the steering rack and turn the wheel from lock to lock to kick the old fluid out"?

      Is pulling a vacuum on the cooling coil absolutely necessary? Or will the lock-to-lock method get enough out to get me most of the way there?

      Cheers,

      M.

      Comment


        #4
        Necro alert!

        I just flushed my 325i's PS following this guide, and it worked perfectly - job done in around one hour. The trick with the vacuum on the 22 mm banjo is ingenius; I got 3-4 ounces of fluid I would never have been able to get otherwise.

        Take care with the banjo washers, as mentioned - the stock ones are tin-copper and blend in perfectly with the rack/banjo fittings. I came very close to putting my new copper ones right on top!


        I recommend givng the undercarriage a good clean before putting the splash guard back on - you never know when you'll get the chance again

        Comment


          #5
          I just suck out the reservoir and refill during every oil change. And then do this when I do the diff and trans.

          Comment


            #6
            My car had 110k miles and I don't think it had ever been done. The fluid was coca cola brown and I got an alarming amount of metal out of it. I ended up flushing it a few times. Allegedly there is a filter in the bottom of the PS reservoir but I don't think it does much. I changed my reservoir regardless. Click image for larger version

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            Comment


              #7
              Allegedly there is a filter in the bottom of the PS reservoir but I don't think it does much.
              I think it's only there to stop contaminants getting in when fluid is added.

              I pulled a sample from my reservoir before doing the flush, and it was very dark brown - almost black; the stuff that came out of the rest of the system was more like maple syrup, but smelled burnt. Probably didn't need doing, but it looks to have been the original fluid, I'm on a bit of a strafing run on the fluids, at the moment . Nice to see some really clean cherryade in there, I have to admit.
              Last edited by JMUDoc; 09-03-2021, 07:06 AM.

              Comment


                #8
                Originally posted by Nuclear Rabbit View Post
                Allegedly there is a filter in the bottom of the PS reservoir but I don't think it does much. I changed my reservoir regardless.
                No filter, the white disc is a diffuser to diffuse high pressure oil returning into the reservoir. The reason why fluid spills out of the hole is pressure in the return from running at high rpms. Not heat and thermal expansion.

                Do change the reservoir since there is probably a lot of crap under the diffuser.

                Comment

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