Any GOTCHAs with Brake Fluid Flush on the E70?
 

Time to flush the brakes, been two years I guess, service indicator yelling at me each time I start the car.

I'm assuming it is straight forward, but wanted to make sure there were no Gotcha's involved, like needing to 'plug in' and cycle the ABS pump or anything?

Was figuring on Traditional or Pressure bleed method similar to this article, unless there is something I am missing..

Asked the dealer for a quote, thinking it would be something like $100-$150, but they think $300 is a reasonable cost for this service :wow:

Think I'd rather spend $50 to invest in a pressure bleeder..

^Yikes. Had the wife's 35d done at the local dealer for ~$125 a couple of years ago. Sorry, no help on the procedure.

Mine was $109 plus an $8 miscellaneous shop fee. The pressure plus cycling that they do seems to do rhe trick vs. my pressure and pedal pressing alone. I'm happy to have them do the flushing alternating with mine but probably not at $300.

Don't use excess pressure, if you have the caliper removed make sure the piston is restrained or it will pop out and don't let the cylinder get uncovered/reservoir empty.

Shouldn't be any reason to run the ABS solenoids if you don't let the master go dry and get air in the system.

No Indy shops near you? Mine charged about $120. One hour labor plus fluid.


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The local BMW dealer had a coupon $100 for brake bleeding. The BMW tech said they will not run ABS bleed procedure.

I've bled the brakes on the X5M with a pressure bleeder. It was straight forward. The only thing that was different was each caliper had two bleed screws. This may only apply for the X5M calipers.

Get a Motive branded power bleeder to flush & properly bleed the brake system... Makes it an easy, one person job without the potential risk of causing seal damage to your master cylinder... & it actually does a good job at bleeding the brakes, unlike pressing the pedal...

DO NOT get the ECS Tuning branded power bleeder, as the fricken top does not unscrew, so you can not clean out the tank & pump assembly properly... Stupidest design I've ever seen, I cuss every time I use it when changing differential fluid... Have been tempted to just throw it in the trash due to how pissed off I get that I can't take the stupid top off, because they glued the threads...

To get ALL the old fluid out, you really should cycle the ABS pump. The Foxwell NT520 Pro w/ BMW software on it can do this & more. Can be found for around $150. I've always had good results bleeding brakes just pressure bleeding the system; however, I've gotten AWESOME results by cycling the ABS pump, where the result is a pedal that feels like it's on a brand new car.

I always recommend against having someone press on the brake pedal to bleed the brakes. If you don't time things right, & know what it is that you're trying to achieve, you'll just introduce air into the brake caliper. When the person pressing on the brake pedal inevitably stomps the pedal all the way to the floor, you're asking for master cylinder damage... When the pedal goes to the floor suddenly, they'll also pump the brakes which will introduce air into the system...

Using a pressure bleeder, I find it get more bubbles out if I tap on the caliper with a rubber mallet. Also, air will get sucked into the bleed ports via the threads if you loosen them too much, where you'll see a constant stream of bubbles & think your caliper is full of air... Crack open the bleed ports just enough to get a decent stream, tap with a rubber mallet, close the bleed port before you run out of pressure from the power bleeder. Also, use a clear tube to put on the bleed port nipple, as it makes seeing fine bubbles much easier; however, don't use a really long piece of hose, as this increases the suction on the bleed nipple that can draw air in via the threads & make it appear you have air in the calipers.

The official BMW procedure involves using a pressurized power bleeder and cycling the ABS pump at the same time. ISTA+ can cycle the pump and talk you through the procedure.

If you’re regular with brake fluid flushes (every 2 years), cycling the ABS solenoids is unnecessary.

I second this ^. I spent hours and 2 full bottles of fluid thinking i had air bubbles but it was in fact sneaking in through the threads.


I never pump the brakes or activate the ABS electronically. I do wait until the next rain and find an empty parking lot to activate them a couple times.


I also live in an extremely high humidity enviro - Alabama

I had the constant air bubbles thing happen to me about 13 years ago on a Cadillac STS...

Only went thru half a bottle until I stopped to think about WTF was going on...

Fluid moving thru an impingement will create low pressure due to Bernoulli principle, the opening of the threads of the bleed nipple internal to the caliper are at 90 degrees to the flow direction, thus will create a slight Venturi & suck in air thru the threads, especially when you're banging on the caliper with a rubber mallet ;)

This does not really compute...

The brake system does not have any appreciable flow (at least it shouldn't in a properly working brake system, else you're going to have a really bad day)... When you flush the brake system, you're only removing the fluid that is available to be flowed, which is NOT the fluid that is locked inside the ABS actuating system...

Actuating the ABS system during normal use also does not create flow throughout the brake line system, it only circulates brake fluid through itself via the positive displacement pump & internal bypass system & actuators, it does not circulate any fluid to, or from the rest of the brake line system, nor new fluid from the reservoir... Actuating the ABS system only circulates brake fluid through itself, it does not get new fluid from the reservoir, thus changing only brake fluid, regardless of age, will not appreciably change out any of the fluid internal to the ABS unit, only the tiny amount of new fluid in the passthru channels will get mixed into the old fluid in the ABS unit...

The ONLY way to get the brake fluid exchanged internal to the ABS unit, is having new fluid flowing from the reservoir to the calipers, while the ABS pump is on & actuators are open, as this provides a constant new fluid stream at the locations inside the ABS pump that are opened & pumped thru the ABS unit, where the old fluid is then carried further down the brake lines to caliper & out of the bleed port...

Without the pump actuated, the entire ABS system is completely out of the loop during a brake flush, where the only fluid that is exchanged is the insignificant amount of fluid volume that is in the passthru channels...

If you examine the hydraulic diagrams for modern ABS / traction control units, you'll see that no fluid can be exchanged out of the ABS system, unless the ABS system is actuated while new fluid is being flowed thru it via a pressure bleeder. The ABS module is where there is the most likely chance for contamination of the fluid to occur...

Being very generous with the numbers: Assume that a very generous 10% of the fluid is exchanged out of the ABS unit if you do not actuate it during a flush.

1st flush, you'll have 90% of the factory fill that is 2 years old.

2nd flush, 81% factory fill fluid that is 4 years old, 9% that is 2 years old.

3rd flush, 73% that is 6 years old, 8.1% that is 4 years old, 9% that is 2 years old.

4th flush, 65% factory fluid that is 8 years old, 7.3% @ 6 years old, 8.1% @ 4 years old, 9% that is 2 years old...

Not flushing the ABS unit out, even at 2 year intervals, simply does not compute...

Thanks SPL15. I stand corrected!

Spl, how much of the total brake fluid is held by the abs parts that aren't actuated?

If let's say , guessing here 10% of the total fluid is in those parts, a normal flush would replace 90% of the fluid. During an abs stop, that fluid would be mixed with the rest of the system and not be all old sitting in there anymore.

He's saying that even when you activate the ABS in action like that, its not like fluid flows freely out of the ABS circuit and into the remaining parts of the system, it moves very little in reality, its just creating brake pressure.

I guess you could go do 20 ABS stops after a flush to try to get some of it to move through, but I am not sure that would even do it.

Agreed, the proper way is to cycle the ABS unit. Did I do it? No, I went to my buddy's garage with a lift and did it manually with NO ABS cycling. I'm fine with that.
Maybe one day when the X5 is in the dealer for something else and its due for a brake flush I'll have them do it by the book.

The thing about flushing brake fluid is to remove water in the system.
Let's say a bad system has 10% water by volume.
If you change 90% of the fluid, now you have an average of 1% by volume water in the system.
Since brake fluid is hygroscopic, water in the abs system fluid amount will migrate to balance out in the rest of the fluid in short time leading to 1% water all over. That's why in older cars I never had issues with just changing the fluid in the reservoir more often. Water in more saturated sections migrates over to drier sections. Of course in the bmw, I do flushes to change more of the fluid but not everyone has access to ista and my point is that changing a majority of the fluid is the key to preventing water buildup and corrosion.

In cases where water doesn't mix with fluid, like silicone dot 5, the water builds up in the low points as the fluid doesn't "hold" the water like our brake fluid does.

Agreed, this is the most practical approach for most of us DIY'ers.

How do you reset the service interval/computer?

You have to access the "hidden" function on the dash just like for the brake replacement, etc. There are a couple youtube vids on this that show it better than any written response on here. GL.

I have a MityVac vacuum pump with the brake bleed attachment that I've used previously with success on various Mercedes from 1970s to 2000s. Anybody used on of these on an X5?

I have. It works. Slowly, but works. I stopped using it though and just went back to the helper on the pedal method. :dunno: YMMV

And more recently... I've just gone to have the dealer do the brake fluid for my last 2 X5's that needed flushing. Guess I'm getting lazier in my old age.

With the motive power bleeder, I've done it with the wheels on when I first got the x5. Just tuck my head under the back for the rears and turn the steering wheel for access to the fronts. It's that easy.

I bled mine while doing a brake job but felt like there would be enough room to do with the wheels on. Good to know! Next bleed is due in ~6 months so I'll probably go that route.

I have one of those brake fluid testers that tells you the % that is water when you dip it in the brake fluid reservoir. Are these useless if it's only testing the portion I can actually reach? It's been almost 4 years since I last did the brake fluid and it's still registering as 0% or < 1% water (OK).

From what I understand, water gets evenly distributed in the system as brake fluid is hygroscopic. The dryer fluid will take moisture from the wetter fluid.

The dirt however will stay by the caliper due to rubber, but then it's the water that kills brakes.

A yearly turkey baster drain and fill of the reservoir is good. But with the motive power bleeder, it's so easy why bother with that method?