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Brake Fluid Change - How To Get the Cap Off

6K views 46 replies 19 participants last post by  Richard230 
#1 ·
My brake fluid in the front reservoir just turned milky. I've never seen that before. So I got to looking at how to change the brake fluid.

The first obstacle I came across was in removing the cap. How do you get that cap off?

Chris
 
#2 ·
Do you have the bobble head reservoir like I do on my F650GS? That requires a cheap metal BMW tool to remove the cap. They keep the cap from unscrewing. Look closely at the area directly under the cap to see the two thin pieces that need to be squeezed inward while turning the cap.
 
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#3 ·
Okay, I figured it out. But in the interests of the next poor BMW owner trying to do this, here's the "tool" you need.



Audio equipment Automotive tire Auto part Gas Automotive wheel system


The "tool" is a shoe string. :D There are two tangs that need to be depressed to allow the cap to turn. The shoe string pulls the tangs out of the way and the cap turns easily.

The brake fluid changed dramatically. It's a creamy color now. Before it was more like a black coffee color. When I pulled the cap off, you can clearly see the condensation under the cap.

Chris
 

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#9 ·
Okay, I figured it out. But in the interests of the next poor BMW owner trying to do this, here's the "tool" you need.



View attachment 354881

The "tool" is a shoe string. :D There are two tangs that need to be depressed to allow the cap to turn. The shoe string pulls the tangs out of the way and the cap turns easily.

The brake fluid changed dramatically. It's a creamy color now. Before it was more like a black coffee color. When I pulled the cap off, you can clearly see the condensation under the cap.

Chris
Very creative and informative. I was also planning to change my brake fluid and pads soon (I've already procured replacement pads and a bleeding tool). I would have been stuck at the cap opening stage as well if I have not come across this post. Thanks!
 
#8 ·
:D Probably since 2014 when the original owner bought it.

I kinda go by the theory that our motorcycles ought to be able to survive the way our cars do. How many people ever check their car's valves? And I'm thinking back 20 years when cars had that on the maintenance schedule. To be honest, I change the antifreeze and brake fluid in my cars when something fails and it has to be done. And I don't have a problem. Most of the cars I have owned, I've kept for 15-18 years.

So to have this happen, was totally unexpected. I knew that dark brake fluid meant I should change it. But I also knew what I felt in normal riding. The brakes work great.

But this? This was like picking up a carton of milk and suddenly finding the milk was spoiled and curdled. OMG!

I have what I need to bleed the brakes tomorrow. It's not hard. And I guess I found the incentive to do it and not wait like I do my cars. :D :D D:

Chris
 
#11 ·
BMW and most other motorcycle manufacturers recommend that brake fluid be changed every two years. However, I find it interesting that on my R1200RS (and other new BMW models) neither the clutch fluid nor the coolant have specified replacement intervals. I recently had my R-bike serviced at SF BMW and was told that the coolant used was the same as that used in BMW cars, was good for the life of the vehicle and would never need to be replaced unless coolant system needed mechanical repairs. That was certainly news to me, as I have always changed my coolant at 2 year intervals. The clutch fluid is a different type of fluid than that used in the brake system and does not absorb moisture from the air (or so they say) which is why it doesn't need to be replaced. :confused:
 
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#14 ·
MGD, Norm Kajikawa and I did the brakes on our ST's with the help of his 911 and lap top. A command makes the ABS pulse while holding the brake lever. I didn't find any difference in the feel of the lever after the cycle took place. We did that a few times for good measure. Unless the ABS has a secret compartment that has ABS use fluid reserved, what goes in at the lever reservoir is what goes out at the brake caliper.
The dealer charged $100 when I had them do it. Norma and I spent a few bucks on fluid. He did have a 911 and his laptop but those are purchases that serve for many uses besides a fluid change so the cost of those will be amortized over a period of time and not specific to the task at hand.
I'm with Daboo on car maint. Cars go many years and don't have the maint schedules followed as many do for motorcycles That neglect of car service has a cost though. I'm about to pay a shop $3200 for the 20 year service on my 4Runner. Dang the bad luck for not doing it myself.
 
#15 ·
On cars I've seen the ABS bleed make a huge difference. Big enough to change the entire feel of the brake pedal and to clear the ABS light on the dash. Per maintenance schedule: it just depends on your vehicle, environment, use, comfort level of the driver/rider to unexpected conditions, and expected cost of future repairs. For instance, on my European cars I am religious about changing brake fluid because calipers can cost over $500 a piece and I'm not chancing rusting up the system. On a Toyota? Who cares if your caliper seizes, junkyard has them for almost nothing. Also, a single caliper seizing on a car isn't a huge deal for me, car will brake fine if not a bit unevenly. I can see being more religious with fluid change intervals and inspecting components for a motorcycle, loosing a wheel or seizing up the engine means a totally different thing on a motorcycle than on an car..
 
#16 ·
When I bought my GS the records indicated that the fluid had never been changed (36k miles), it didn't look bad, but it was darker than I'd like. I flushed until it was clear, then cycled the ABS with my GS-911. When flushing again after cycling the pump, I got enough more contaminated fluid out to make me feel good about going that extra step. I know it will eventually dilute back into the system, but the same cost argument applies here. If the pump were to fail it's a very costly replacement and has to be 'paired' back into the bike by a dealer with the dealers software tools, and they won't do that unless you buy it new from them ($$$$).
 
#18 ·
"He was in the middle of a long trip"
Oil change interval now is 6K and filters at 12K on many bikes. If one is doing constant touring miles that interval can probably be extended. It's the heat cycle and low rpm around town that can wear the oil, from what I'm been given to understand. Or if your bike burns a quart every thousand miles, keep putting new in and don't worry about it. My 80/7 used to burn a quart from LA to Norman, OK. On Air Heads aftermarket oil pans increased the capacity from 2 quarts to 3. Always nice to have a larger oil capacity.
 
#20 ·
I change the brake fluid every two years. It has been my understanding that with brake fluid being hygroscopic (absorbs moisture) that moisture can damage brake parts over time. Pay me now or pay me later. Like anything, I am sure others roll the dice and have no problems.

I have a friend who rides his bike very little so he accumulated low mileage over the course of a year. He would change his oil every 3 years (I used to joke whether it needed it or not!) and store the bike in his outside shed. I cautioned against that practice and said you still should change the oil every 12-18 months - even if only riding 1K miles or less a year. He saw that as a waste of money. Last summer he needed a new clutch on a very low mileage bike. I have ridden with him and he is experienced and does not abuse the clutch. First thing the shop asked after taking the clutch apart was,'how often do you change the oil?".
 
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#25 ·
You live in a humid area and the brake fluid is exposed to moisture in the air through the reservoir cap. It has to vent to atmosphere (to prevent a vacuum) and allow the brake fluid to flow to the calipers as the brakes are applied...and as the pads wear down.

One problem with moisture in the fluid is the corrosion and pitting of the aluminum parts that then can cause a leak where the seals meet it, or in one case I had, a BLOCKAGE of port for the return of fluid back to the reservoir, causing the rear brake to drag as the day got hotter.
 
#22 ·
When I change fluid......the first thing I do is take a Turkey Baster and suck the old fluid out of the reservoir. This allows you to put fresh fluid in the reservoir when you begin the process of getting the old fluid out. There is no need to run that crappy stuff in the reservoir through the system - just to spend more time trying to flush it out. It is likely the fluid down inside is not as nasty as the stuff in the reservoir.
 
#27 ·
There's one inside the reservoir, just like you said.

I had about 5 opened containers of brake fluid in the garage. They are probably 10 years old. Interestingly, all of them look fresh. I would've thought that by now, they would show signs of contamination.

Chris
 
#29 ·
There's one inside the reservoir, just like you said.

I had about 5 opened containers of brake fluid in the garage. They are probably 10 years old. Interestingly, all of them look fresh. I would've thought that by now, they would show signs of contamination.

Chris
If you really want to test 10 year old DOT 4 try the following or similar :-

https://www.lasertools.co.uk/product/4875

Personally, and like most I'd imagine, I'd just buy a small bottle of fresh stuff from a factors for very little money. I'd be safe, and know that I'm not pouring a further problem into my brake system. But then again each to his/her own degree not excitement.

Stop safely.

Sent from my moto g(6) play using Tapatalk
 
#34 ·
The reason that I change my brake fluid every two years is because brake fluid is a lot cheaper than the cost of replacing a corroded sticking brake caliper with a new one. [;)]
 
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#36 ·
It's fun reading these threads. I love spellcheck that helps us say what we don't mean.

"Guess I'll always struggle to understand the rationale of "wait untill it breaks" when it comes to break system maintenance." Haha that is break system maintenance for sure.

On a more serious not I just got my bike back from the 24,000 mile service. They did change the brake fluid along with the drive belt, tensioner, spark plugs and air cleaner along with checking valve clearances. I'm about to post the valve clearance to that thread - all were OK except for one intake at 0.2 instead of between 0.27 and 0.33.
 
#39 ·
Some interesting questions in this thread. As I understand it, Glycol based brake fluid is hydroscopic and will, over time absorb moisture from the air through microscopic pores in the hydraulic lines and seals. Hence the need to change at regular intervals. I don't know if the colour change is related to how much moisture has been absorbed. I do know that the brake fluid in the rear reservoir of my ST and both my GT's went brown after a year due to some kind of dye in the rubber hoses leaching into the fluid. After changing the fluid on those bikes, it always stayed a nice yellow colour between fluid changes. I think that silicon brake fluid is hydrophobic, which means it doesn't absorb moisture and has been used on US military vehicles since the early 90's for that reason.
 
#40 ·
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