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Topic: Brake Bleeding... What am I doing wrong?  (Read 16535 times)

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« on: December 16, 2006, 12:06:29 am »

I found that the rear brakes weren't working and when I took the cover off the master cylinder I found that there was no brake fluid.

I bought some brake fluid at my local BMW dealership and picked up a brake bleeding kit at Kragen.

I set up the brake bleeding kit and connected it to the brake bleed valve while it was closed to make sure it held pressure.  It did.  So I filled the master cylinder with the brake fluid and then cracked open the valve.  Well really I kinda opened it really wide because it was on really tight and I was pulling really hard to get the nut to move.  I got a little bit of fluid and then nothing but air.

I tried having someone press the brake pedal while I cracked open the valve and then closing it, but I'm still just getting air.

Any ideas?
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« Reply #1 on: December 16, 2006, 12:24:18 am »

Press down on brake pedal then slowly open the valve. When the brake pedal is maxed-out close the valve then release the pedal.

If your system was totally dry you will need to repeat this over and over again until you get all the air out of the system. You also will probably need to keep an eye on the master cylinder and refill it as the air is pushed out of the system & makes room for the brake fluid.

The little bit of brake fluid you got on the first attempt was the old stuff that was in the system already.

 Smile
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« Reply #2 on: December 16, 2006, 12:27:11 am »

The pressure on the bleed pump gauge doesn't change when I push on the pedal  Should I be worried?
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« Reply #3 on: December 16, 2006, 12:40:50 am »

Donít know; I never used any fancy gauges, just an old fashioned wrench to bleed brakes.

But the fact that the system was very nearly dry would prompt me to check all everything for possible leaks. Brake systems tend to hold their fluid for a long, long time, unlike Harley engines & oil.  Bigsmile

What year and model is the bike? Maybe a BMW guy will pipe-in here.
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« Reply #4 on: December 16, 2006, 01:34:48 am »

I'm wondering if it has something to do with the ABS..  

2001 BMW F650GS Trying to bleed the rear brakes
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« Reply #5 on: December 16, 2006, 02:06:25 am »

the fact that the system was dry means there is either a leak in the system, or the brake pads are worn out and the system was low to begin with.  As mentioned, definitely look for leaks and check your rear brake pads

What I would recommend on bleading your brakes, first thing is, toss whatever brake bleeding "kit" you bought into the corner of the garage and forget it exists.  I don't know which particular type of setup you have, but it really doesn't matter.  

Now.  Doing this the old fashion way, close the bleed valve on the caliper, make sure there's fluid in the reservoir, then pump the brake lever multiple times.  Hold down the lever, after pumping it several times.  Then, while still holding the lever down, crack open the bleeder.  While still holding the lever down, close the bleeder.  Now release the lever, and pump it several times and repeat everything I just said.

You will eventually get all the air out using these simple steps.  That won't necessarily make everything happy.  This will remove all the air out of the system, but may not get the air out of the master cylinder.  When a master cylinder is pumped dry, sometimes air gets caught in the pressure cups and is difficult to get out.  It can require other arcane methods, such as "diddling" the lever, and/or leaving the lever actuated overnight.  But lets just get to this point and see if you have further issues, before we go there.
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« Reply #6 on: December 16, 2006, 05:52:20 am »

If BMW's ABS system is like Triumph's, you'll need to have the dealer bleed it for you.

Triumph's ABS system requires their diagnostic computer to tell the ABS computer to leave to control valves (or somesuch thing) to stay open during the process.  Otherwise, you'll never get the air out.

I'd ask this in the BMW forum, or call the dealer.
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« Reply #7 on: December 16, 2006, 10:32:00 am »

Thanks for the replies guys.  I did try the "old fashioned" way as well and didn't get anything.  I'm thinking that maybe the ABS is preventing me from getting the air out, but I'll check with the people in the BMW forum and probably call the dealership later.  I'll update when I get this sorted out.
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« Reply #8 on: December 16, 2006, 12:17:09 pm »

Nny, I posted this in the BMW section as well, in hopes that you would catch it in one place or the other.
Also, if you are going to be doing the work to your bike you should invest in a factory repair manual.  The procedure is laid out pretty clearly in it.  Anyway, here is the post I made over in BMW.

Not sure what your brake bleeding kit looks like, as I cant get your link to work.  Doesn't matter though.  Fill the reservoir with fluid, push down on the brake pedal and hold it, then crack the bleeder valve on the caliper.  As soon as you get fluid, close the bleeder valve, let up on the brake pedal and check to see if you have brakes.  If they are still spongy, then repeat that process.

I've never used any of the kits or anything, I usually just fit a small hose over the bleeder nipples and run the other end back into the bottle of brake fluid.  Keeps me from making TOO big of a mess.

Hope this helps.  It's the only way that I know of to bleed brakes.

P.S.  Also should have mentioned that you need to keep an eye on the brake fluid reservoir level.  Check its level and keep it at the proper level, each time after you've closed the bleeder.  Very important that the fluid remains above the hole that replenishes the brakes, otherwise you will just be drawing more air back into the system.

P.S.S.  I also should have mentioned that I dont know how your bike's brakes are set up exactly, but if they are like my ABS brakes, then your rear reservoir is actually split into 2 reservoirs.  My bikes hand lever actuates the rear and front brake, whereas the brake pedal actuates only the rear.  This necessitates the split reservoir in the rear I suppose.  I'm assuming here, that your ABS setup is going to be the same.  So make sure that your levels are good in both halves of the rear reservoir.  Also the level is very sensitive.  I get brake warning lights if my level dips the tiniest bit in either half.

Oh yeah, my bikes an 04 bmw K1200RS by the way.
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« Reply #9 on: December 16, 2006, 12:23:43 pm »


If BMW's ABS system is like Triumph's, you'll need to have the dealer bleed it for you.

Triumph's ABS system requires their diagnostic computer to tell the ABS computer to leave to control valves (or somesuch thing) to stay open during the process.  Otherwise, you'll never get the air out.

I'd ask this in the BMW forum, or call the dealer.


Sounds pretty strange to me.  Wouldn't this make it rather difficult to work on the bike, move it around etc. when the bike isn't running or the ignition is off ?  For that matter, why couldn't you just turn the ignition on to power the ABS computer, when you bleed the brakes ?
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« Reply #10 on: December 16, 2006, 12:50:00 pm »


Triumph's ABS system requires their diagnostic computer to tell the ABS computer to leave to control valves (or somesuch thing) to stay open during the process.  Otherwise, you'll never get the air out.

I'd ask this in the BMW forum, or call the dealer.


If the ignition is off when you do the job the ABS cannot activate or record any weird signals it doesn't like. Done my Triumph ABS system a couple of times and also checked for proper functioning of the ABS afterwards, no problems.

However, if the system has recorded a fault then it may need to be re-set by the dealer.  My guess is that you just haven't gotten all the air out yet.

Pump-up/hold/bleed/close/repeat.  A few systems will gravity bleed but many refuse this technique.

As mentioned though, BMW guys will know if something special has to be done and an empty system points to other problems besides fluid level (which also might be why you can't it to bleed properly).

 
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« Reply #11 on: December 16, 2006, 12:59:37 pm »

Besides a wrench this is the only tool I use to bleed brakes, it cuts down on the mess. Though mine has a clear tube making it easier to see what is being pumped out of the system, air or fluid.

Brake bleeder
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« Reply #12 on: December 16, 2006, 01:14:36 pm »


Besides a wrench this is the only tool I use to bleed brakes, it cuts down on the mess. Though mine has a clear tube making it easier to see what is being pumped out of the system, air or fluid.

Brake bleeder


Same here.  I have several sections of clear tubing, different OD's.  I can usually find something that works, whether it be car or bike.
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« Reply #13 on: December 16, 2006, 02:06:03 pm »

assuming its not a servo system, the fact that it has ABS really doesn't matter.  Its the exact same proceedure either way.

I can't speak for servo systems, I'm not familiar enough with them to comment on it.  But I blead brakes on cars every day, and 90% of them have ABS.  Exact same thing.
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« Reply #14 on: December 16, 2006, 03:30:01 pm »

I dunno nuffin' `bout dem fancy ABS systems...

...but  I have noticed that when you run the rear master-cylinder dry, there is often a bubble of air trapped in the hose between the reservoir and the master-cylinder... fill the reservoir and then pinch the tube that connects it to the master-cylinder repeatedly until you stop seeing bubbles come up from the hose in the bottom of the reservoir.  Only then will any bleeding-efforts produce results.
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« Reply #15 on: December 16, 2006, 09:46:35 pm »


I dunno nuffin' `bout dem fancy ABS systems...

...but  I have noticed that when you run the rear master-cylinder dry, there is often a bubble of air trapped in the hose between the reservoir and the master-cylinder... fill the reservoir and then pinch the tube that connects it to the master-cylinder repeatedly until you stop seeing bubbles come up from the hose in the bottom of the reservoir.  Only then will any bleeding-efforts produce results.


Ooh.. that's something I didn't think of...  I'll do that.  Someone in the other thread suggested putting teflon tape under the bleeder valve too and I think I may need to do that as well.  Thanks for all the help guys.
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« Reply #16 on: December 16, 2006, 10:33:11 pm »


assuming its not a servo system, the fact that it has ABS really doesn't matter.  Its the exact same procedure either way.




Assuming the BMW system is similar to the Triumph system, it is not.

You do need to bleed the system as you normally would.

Then you need to use the system diagnostic tool to cycle the modulator solenoids, while applying pressure to the brake lever and cracking the bleed valve.  You need to repeat this process until all air is out of the system.

Then you have to repeat the normal bleed process again.

If you don't bleed the system while the solenoids cycle, you can still have air trapped in the system and not know it.

Just turning the bike on is not enough- the solenoids need to be cycled, and the computer has to tell them to do it.

The BMW process may be different.  The only way to know is to check a shop manual or call the dealer.
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« Reply #17 on: December 17, 2006, 01:04:47 am »

I would argue the details, but I'll just say, that is only for "special circumstances".  I'll leave it at that.  95% of the time, you do not need to cycle anything to blead the brakes, ABS or no.

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« Reply #18 on: December 17, 2006, 08:59:33 am »


I would argue the details, but I'll just say, that is only for "special circumstances".  I'll leave it at that.  95% of the time, you do not need to cycle anything to blead the brakes, ABS or no.




Well, the procedure may be different for BMW ABS.

The procedure I outlined was straight from the Triumph Service manual.

Even bleeding automotive ABS, if you want it done properly, requires special procedures beyond "step on pedal, open bleeder, close bleeder".
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« Reply #19 on: December 17, 2006, 01:47:50 pm »


Even bleeding automotive ABS, if you want it done properly, requires special procedures beyond "step on pedal, open bleeder, close bleeder".


as soon as the master goes dry, the brakes stop working.  There is no air in any of the valving for the ABS modulator, whatever type it is.  The only time it would even been feasible would be if you had a leak at the modulator.  Even if you had a leak at the caliper, the same thing would happen, the master would go drop and the brakes would no longer work, which would prevent the ABS from engaging.

The only thing actuating the modulator does, is get you the tiny tiny bit of "old" fluid out of it.

So to reiterate, if you are getting air out of the system, it will never be in the ABS modulator itself.  

Just because there's a procedure in the manual, doesn't mean its necessary
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