Changing/flushing power steering fluid
I have 30,000 miles on my M3 and plan on keeping her a long time, so I thought I'd change the power steering fluid. The car has been in the track and has boiled the fluid a couple of times. This is my daily driver so I'm pretty meticulous about having all the correct parts and pieces around for any work so that I don't end up stranded with a car that won't run sitting in my garage.
ONE CAUTION: I had to go to the dealer 3 times to get the two crush washers for the hose fitting to the upper power steering pump line. It's the smaller of the two and requires a 19mm socket to loosen. Guess what? The upper crush washer and the lower one (the one that sits on the steering rack) are two different sizes. The lower one is the larger of the two and the one for the top of the banjo bolt is the smaller one. Of course what I ended up with were two lower washers.
So the plan of draining, filling and draining one more time is out the window. I can't risk removing the fitting two times since I don't have a replacement upper washer. I'm just hoping it doesn't leak when I put it back together. Hope I have good karma today. I'll post pictures tonight.
Really it's not too hard. Just need to remove the lower front cowl (the black one) and the aluminum lower pan/engine cover. First drain the fluid out of the reservoir then take a 19 mm socket on a really short extension. My shortest standard extension was too long so a 3/8" to 1/2" adapter with matching socket was just the right length. Loosen the 10 mm power steering fluid line bracket which is about 8" or so from the terminus at the rack which allows you to move the line away from the rack. Have your drain pan handy and loosen the 19 mm bolt on the upper power steering rack line. It will start leaking immediately and drain down the aluminum suspension mount channel in various locations but mostly under the steering rack. Turn the steering wheel back and forth a couple times and more fluid will come out. DO NOT START THE CAR. Clean up your washers for the banjo bolt as below or replace with new and then refill your reservoir. Fill the reservoir full, then start the car and let it run for 30 seconds. You'll notice the fluid is a bit foamy, but settles down in a few minutes and then refill to full. Restart the car and let it run a few minutes, turn the steering wheel back and forth a couple times. Check for leaks at the fitting you just tightened and check you reservoir level again. Refill as needed and you should be done. Ideally you would do this procedure one more time to really get a good rinse but I didn't want to risk it with one old washer and one new one. After you are all done you will still probably have power steering fluid dripping from various areas. Don't freak, it's left over from the drain. Just do your best to get as much as you can (you can't reach all of the areas where the fluid runs) but get as much as you can and realize you'll still probably have some drips later.
Last edited by VictorH; 10-01-2011 at 08:04 PM.