How much Brake Fluid to Flush?
 

2018 R1200 GSA

Just finished watching a video by a BMW mechanic saying that BMW does not require cycling of the ABS system when flushing the brake fluid, but to make sure you use the volume of fluid specified to meet their standard. The RT he was working on was an older ABS equipped model and said for this bike it was 2 full bottles of fluid. Assuming they are 500ml each, then I would guess that he used 300ml for the rear, and 600ml for the fronts?


I have not been able to confirm the quantity BMW requires to meet their specification for brake fluid flushing.

Has anyone seen this spec? Or know the quantity?

Please note, I have flushed many brakes in vehicles, trailers and bikes, and I flush until clean fluid appears, but I also use up the entire bottle of fresh brake fluid as it deteriates once opened, therefore no sense leaving it sit on a shelf.


thanks
brian

I should also mention that the mechanic when saying that BMW doesn't require the ABS cycling when doing a brake flush according to their manuals, it is for a properly working system that hasn't been opened or have air in it.

If you change a line or accidentally got air in the system, then yes you need to cycle the ABS system

Type in your code

https://www.bmw-motorrad.ca/en/servi...er-manual.html

thank you but that link is for an owners manual which I already have.

Thought filling capacity is shared in the manual or in a tech sheet. Sorry!

I am a BMW technician. I have changed fluid on THOUSANDS of BMW's of all ages and types. Including yours.

When you bleed, or more accurately, change the fluid in your 2018 GS, you will be changing the fluid in the ABS pump if you like it or not. It's an integrated system.

You should change it like any conventional braking system. There are no separate bleed valves on the ABS pump like in the older pre-2006 ABS pumps.

A 500ml should be enough to change the fluid in the entire system. When doing this job in a dealership, you are given one 500ml bottle for the entire task.

I would drain the reservoirs (by pumping or syringe) until they are almost empty and then clean the reservoirs if there is any gunk in them. Then fully fill them with fresh brake fluid. On the front , you gently squeeze the lever 1/12 of its travel to remove any trapped air in the master cylinder and squeeze the hose to the rear reservoir to do the same. Then I would pump this new fluid until it is almost empty again. Then you fill to the max limit on your reservoir and replace the cap.

Like you, I keep going until the bottle is empty. Why wouldn't you. With one 500ml you should be able to flush about three rear reservoirs and two full reservoirs on the front. One per calliper.

As you say, an open bottle shouldn't be used after six months or so. BMW advise brake fluid be changed every two years or 12,000 miles IIRC

If you read BMW's instructions in their workshop manuals (which you wont have or have access to) you should have your pistons pushed fully into the callipers before you do this. And you would also perform a bleed test on the older pumps.

However, NO BMW dealer does this that I know of. It's totally un-necessary.

When I have changed ABS pumps or entire brake line systems (so starting with a dry bike), it will generally take one 500ml bottle to fill the entire system including some bleeding. And I will use another bottle to bleed again just to be sure.

You don't need any fancy one-way bleeders, Mityvacs or other vaccuum bleeders for this task. Just some clear hose and an old bottle. It's actually easier like this.

The MOST IMPORTANT thing is to not introduce air into your system when changing fluid.

You can buy these manuals on multilanguage DVD
https://duckduckgo.com/?t=ffcm&q=01598405652&ia=web
01598405651 will be for K51 (R 1200 GS Adv., R 1250 GS Adv.) - (09/2012 — 07/2018)




(or you check for a torrent)

I just checked my genuine BMW dealer software.

"Keep pumping the lever until fresh fluid emerges".


So that's how much brake fluid it takes. They don't give you a figure. Brake fluid capacity isn't listed in any other technical documentation I can find.

Probably to stop people using that amount and thinking "Job done"

Thank you Touring Ted for taking the time to reply and explain this clearly.

There are many posts on other forums advising to push the pistons back and to cycle the ABS to fully flush the system. I can see the logic in doing this if you are dealing with a neglected bike, but for a regularly serviced one.....not needed as you stated.

brian