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      10-28-2009, 12:32 AM   #1
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Drives: Silver e92 M3
Join Date: Jan 2009
Location: South SF Bay

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Arrow DIY: Brake fluid flush

Hi folks,

Someone asked a while back how to do a brake fluid change. After my last track event, I flushed my fluid and took a few pics. Hope this helps!

Warning - All the standard stuff applies. Get that car on jack stands and stable. Don't be an idiot. Be careful with brake fluid, it will eat your paint.

What you'll need:

A couple feet of clear plastic tubing (1/4" I think)
An old soda bottle
9mm wrench (rear)
11mm wrench (front)
brake fluid
A friend or a pressure bleeder
jack and jack stands
17mm socket and a breaker to remove the wheels

1) Put the car up on jack stands
2) Pull the wheels off (wouldn't this be a good time to give them a nice bath?)
3) Assemble your old fluid bottle. I poked a hole in the soda bottle cap and fed the tubing through. Put enough brake fluid at the bottom of the bottle to submerge the end of the tubing.

4) The brake fluid reservoir is under a panel on the driver's side of the engine bay, right under the windshield. Three screws and a button removes the panel, but be careful, there's a couple wires there still attached. I just flipped the panel over. There is a plastic piece surrounding the reservoir and the abs pump (still there in the pic) that just pops out. You don't have to remove it, but I found it easier to see how much fluid was in the reservoir with it gone.

5) Start at the furthest wheel from the master cylinder (passenger rear). With the wheel removed, you'll see a small nipple under a rubber cover on the backside of the caliper. There is a small nut on the bottom of the nipple. Pic of the nipple with the rubber cap removed:

6) Get your wrench around the nut - you only need to turn the nut about a quarter turn (maybe less), so position your wrench accordingly. I use the closed end of the wrench. Put the end of the tube leading to your fluid catch bottle over the nipple. Paper towel optional, but there will probably be a little dripping.

7) Here's the part with no more pictures. Make sure your brake fluid reservoir is full. You can use a turkey baster or something to remove as much old stuff as you can so you don't have to pump it through. If you have a pressure bleeder, attach it to the reservoir, and pressurize. If you're reading this, I'm guessing you don't, so have a friend pump the brakes a couple times and hold the brake pedal down. Once your friend gets to the hold it down stage, open the nut and you'll see fluid coming out the nipple into the bottle. Close the nut, pump and hold brakes, open nut, repeat until fluid runs clean. Once the fluid is clean, move on to the driver's side rear, then passenger side front, and finally, driver's side front.

If your fluid isn't that dirty, it can be hard to tell if you're pumping out new fluid or not. If you're going through a whole reservoir of fresh stuff, you're probably good. If you look at the first pic, that black cloud is dirty fluid .

A few things to watch out for:

Don't let up on the brakes when you open the nipple. This will draw the dirty fluid back into the system and worse, possibly air. This is why you want to stick some *clean* fluid at the bottom of the catch bottle.

Make sure your brake fluid reservoir is always topped up - you don't want to pump air in the system from the other side either. If you do get air in the system, you'll have to keep pumping the pedal and flushing fluid through until you don't see any more air bubbles coming out the tubing.