Feb 17, 2009
BMW Brake Fluid Bleed/Flush DIY
This DIY article will address how to flush or bleed a BMW X5′s brake system. Or for that matter, any BMW model.
Subject used was my wife’s 2002 E53 X5 4.4. All BMW (or german) master cylinders use the same size cap. This makes the Motive Power Bleeder a good investment if you have a few different BMW or german cars. The bleed nipple screw will be of different sizes tho. For the purpose of this writeup, the tools and pictures will be specific to the BMW E53 X5 (doesn’t matter which sub model). These procedures can be adapted to aftermarket brake calipers also (ie: Brembo, Stoptech, etc).
After 4 years of service, the fluid looks like it was never flushed before. Very dark, like tea or coca cola. New fluid is very light yellow/honey color and definitely transparent (with the exception of the dyed fluids).
Modern BMW systems are specified to run DOT 5 brake fluids. However, DOT 4 is acceptable (and in most cases have a better performance due to the larger variety of high performance fluids available in DOT 4). I chose to use ATE Typ 200 (standard) DOT 4 brake fluid. I’ve been using this for years on BMW, Mercedes and Porsches with great success on and off the track. I find it to be very economical for the tempurature range it performs in. When in doubt of which fluid to use, go to your dealer for the factory fluid (BMW uses one of the ATE OEM fluids).
All brake fluid is hygroscopic, meaning it sucks the moisture right out of the air like a sponge. If you open a bottle of new brake fluid, the entire bottle is considered used now. You cannot store the remainder of the fluid longer then a few days, maybe a week at most, before the fluid starts to absorb moisture out of the air.
BMW recommends changing your brake fluid every 2 years.
You should also bleed your brakes whenever you feel the pedal to be soft and mushy.
There are 3 ways of bleeding your brake system: 2 person traditional pump and hold method
Bleeding all of the fluid results in flushing it.
The first method, I’ll describe only. The following directions are for the faster and easier 1 man method of pressure bleeding. I’m not a fan of the last method (vacuum bleeding) and will not be discussing that in this article. I chose the Motive Power Bleeder because it has the correct cap fitment over the german master cylinders.
I perform this procedure at least once a month as I race often and will not compromise my ability to stop. Sometimes I do this 4 times a month depending on how much I race (enduro and sprints). On my street cars, I do this at least every 2 years, but somethimes every year if I remember or have the free time. For the price of the brake fluid, its pretty cheap peace of mind.
Skill Difficulty: 1 out of 10.
Time Required: 1 hour or less depending on experience.
This is what worked for me. If you are not sure nor comfortable doing any of these steps, please DO NOT attempt to perform this procedure. Rather take your vehicle to a qualified mechanic or brake shop for the work to be done. Do not take your vehicle to a friend that does not understand this document either (2 confused minds will not make it better). You cannot hold X5World nor me responsible for any damages YOU may have caused on YOUR vehicle (we weren’t there and didn’t do any of it, thats the story and I’m sticking to it). But seriously, it ain’t all that hard to do.
11mm combo wrench
Power Bleeder Kit (for 1 man operation)
brake fluid (1 Liter for full flush, less for bleeding)
The following procedures assumes you have the vehicle lifted and all wheels removed already.
2 Man Manual Operation
Get in the vehicle and prepare to pump the brake pedal (LOTS). The tasks of the Helper is:
The Helper will pump about 5-10 times and hold the pedal down.
The Helper will yell to the Bleeder Person that the pedal is HOLDING.
The Helper will only release the brake pedal when the Bleeder yells RELEASE.
The Bleeder Person
This is the person actually doing the bleeding of the brakes.
Open the Master Cylinder.
If flushing, then use the turkey baster to remove as much fluid as possible. When as much of the old fluid is removed, fill and top off with fresh fluid. Look below for detailed instructions and pictures.
If light bleeding only, then make sure the master cylinder is topped off with brake fluid, then close it.
Start at the wheel FURTHEST away from the master cylinder.
Open the rubber cap ove rthe nipple
Place the 11mm wrench over the nipple screw.
Place the clear hose over the nipple.
Yell to the Helper to start pumping the brake pedal.
Helper pumps 5-10 times and then holds the brake pedal down. Helper will yell back “HOLDING” when he/she is done.
The Bleeder will then crack open the nipple screw about 1/5th to 1/4th turn.
Brake fluid will start to seep out into the hose and the Helper’s brake pedal will drop.
When the fluid stops flowing out of the hose, the Bleeder will close the nipple and yell “RELEASE” to the Helper.
The Helper can now release the brake pedal. It is very important that the Helper does not release the pedal while the nipple is open. This will draw air back into the caliper.
Repeat the pump and bleed sequence until all air bubbles are gone.
After 4-5 iterations, check the master cylinder to ensure there is still fluid in it. DO NOT let this run out as you will draw air into the system that way. Top off with more brake fluid.
If flushing, repeat till you see new fluid starting to seep out while bleeding.
Once this brake caliper is completed, move to the next wheel that is 2nd furthest from the master cylinder. And repeat the bleed process.
Continue on to the next wheel that is 3rd furthest from the master cylinder and repeat.
Be sure to check the master cylinder and top it off with fresh brake fluid OFTEN.
Step 1: Power Bleeder Operation
Remove the dust shield over the master cylinder
The dust shield is the long plastic shield next to the windshield
The master cylinder is the white bottle underneath it on the driver’s side.
The dust shield is held in place by 6 sprung twist locks.
The two twist locks holding the long rectangular piece in the middle is for the microfilter. You do not need to remove that.
Simply turn them so they pop up then remove the whole dust shield to gain access to the master cylinder.
Step 2: Remove the master cylinder cap
Disconnect the wire harness to the sensor on top of the cap
Disconnect the wire harness from the side of the bottle so you can move the wire harness out of the way
Twist the cap off and remove
Clean the cap with a lint free shop towel
Place the cap somewhere safe so it won’t pick up dirt and debris. I wrapped mine up in a lint free shop towel.
Step 3: Load the Power Bleeder
Twist off the top of the Power Bleeder and pour in your NEW brake fluid.
For a full flush, I like to use 1 Liter. I chose to use ATE Typ 200 gold fluid (DOT 4).
Reserve about 1/5th to 1/4th of the bottle for later. You will use this to top off the master cylinder.
Close the Power Bleeder.
Step 4: Remove the old fluid from the master cylinder
Using the turkey baster and a shop towel, suck as much of the old fluid out
Squeeze the turkey baster before you dip it into the master cylinder.
Once the turkey baster is filled, remove it carefully and tilt it up so the tip is pointed up. Use the towel to stop it from dripping.
Have I mentioned that brake fluid is a GREAT paint stripper? Do not drip any of this on your car. Use the towel to hold close the top of the turkey baseter tip.
Dump the old fluid into a container that you will take to recycle this fluid.
Remove as much as you can. The more you have in there, the more you will have to bleed out.
Step 5: Mount the Power Bleeder and Pressurize
Twist the cap of the power bleeder onto the master cylinder
Take care not to twist the hose too much. There is no swivel fitting.
Place the power bleeder where it can sit fairly straight up
Pump the handle on the power bleeder until you reach about 20 PSI.
Wait 1 minute to check for air leaks. If you have a leak, tighten the cap some more.
The correct fitment on the master cylinder allows us to get to 20 PSI. otherwise a generic fitment using a chain squeeze method can only get to about 10 PSI.
Step 6: Bleed the furthest caliper from the master cylinder.
On Left hand drive models, start at the passenger rear caliper.
Pop off the rubber cap over the brake bleed nipple.
Place the 11mm wrench over the nipple nut.
Put the hose over the bleed nipple.
Put the other end of the bleed nipple into your catch bottle.
I use a .5L clear drinking bottle.
Typically when flushing, you fill 1/3rd of the bottle per caliper will get all of the old fluid out in the particular caliper and lines.
Crack open the bleed nipple about 1/5th turn only.
Watch for air bottles in the clear hose.
You may want to close the nipple and hit the caliper with a rubber mallet to jar loose air bubbles periodically.
Continue to bleed till there are no more air bubbles or until you see fresh clear fluid with no air bubbles.
Close the bleed nipple and remove the hose and wrench.
Close the rubber cap over the bleed nipple.
Step 7: Check Power Bleeder and Move to next caliper
Check the Power Bleeder to ensure you still have Fluid left to feed into the Master Cylinder and that the pressure is still enough to bleed with.
I typically lose about 2-4 PSI after bleeding one caliper.
Pump up the pressure back to 20 PSI.
Repeat step 6 for the next caliper.
Bleed Sequence for Left Hand Drive model – Furthest to Closest caliper to the master cylinder: Rear Right (Passenger’s Rear), Rear Left (Driver’s Rear), Front Right (Passenger Front), Front Left (Driver’s Front).
Repeat Steps 6 and 7 till all calipers are completed.
Step 8: Discharge Pressure and Disconnect Power Bleeder
Tilt the Power Bleeder on its side so that the side where the hose attaches is on the top.
Crack open the top of the Power Bleeder to release the pressure.
Alot of air will bubble through the hose, don’t worry about this.
Disconnect the cap from the master cylinder.
Use a paper towel to catch the drips from the cap and remove the Power Bleeder from the car.
Step 9: Top off Master Cylinder
Remember how we saved about 1/5th or 1/4th of the fluid from the bottle? We now use that to top off the master cylinder to the MAX LINE on the side of the bottle.
Be careful not to spill.
Step 10: Reassemble everything
Place the clean master cylinder cap back onto the master cylinder.
twist it tight but keep the sensor pointing to the front of the vehicle
Reconnect the wiring harness
Tuck the wiring harness back into the side holder on the master cylinder bottle
Reinstall the dust shield
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