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Brake bleeding issue

Ctot

Just got it firing!
Joined
Jun 4, 2022
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Location
PA
Hey there, I was trying to replace the rear brake fluid on my 2015 v7 and I've got clear fluid coming out of the bleeder but no pressure. I pump the brake pedal, Crack the bleeder, close it pump again and no pressure builds up. I've put about 3/4 of a bottle of DOT4 fluid in it. Could it be a seal in the master cylinder or is there something I'm just stupidly missing? The brakes were working fine before the fluid was just all brown and gunky. Thanks for any advise!
 
Make sure you have a little play on end of master, a bit of pedal play. That way piston comes out to end, refills with fluid. You could also take caliper off and bleed it above the master level, air goes up then. Stick a wrench in between pads. Tractor supply sells a hand pump power bleeder or Amazon.
 
I change the brake fluid in my three bikes annually and on rare occasion I'll get a bit of air in the front or rear brake system. When this happens I simply tie down the brake lever to the fully compressed position and leave it overnight. The next morning I release the lever and pump the brakes two or three times and they will be "rock solid".

Notably, some folks on this forum denounce this method, but I've used it successfully for over thirty years on everything from British, Japanese, American and Italian manufactured motorcycles.

Jason
 
Hey there, I was trying to replace the rear brake fluid on my 2015 v7 and I've got clear fluid coming out of the bleeder but no pressure. I pump the brake pedal, Crack the bleeder, "PRESS THE PEDAL TO THE BOTTOM OF THE STROKE" close it pump again and no pressure builds up. I've put about 3/4 of a bottle of DOT4 fluid in it. Could it be a seal in the master cylinder or is there something I'm just stupidly missing? The brakes were working fine before the fluid was just all brown and gunky. Thanks for any advise!
I assume you are doing it as I corrected. If so pull the calliper and raise it above everything else.
 
Yea, I keep the pedal pressed down when I Crack it. Unless you mean after I crack it, then depress the pedal. I got a hand pump vacuum bleeder today and tried that. It worked great on the front but still no pressure on the back. Either I have gotten a lot of air in the line ( which I may have done) or air is coming in from somewhere else. I'll try raising the caliper tomorrow. Thanks for the advise.
 
I change the brake fluid in my three bikes annually and on rare occasion I'll get a bit of air in the front or rear brake system. When this happens I simply tie down the brake lever to the fully compressed position and leave it overnight. The next morning I release the lever and pump the brakes two or three times and they will be "rock solid".

Notably, some folks on this forum denounce this method, but I've used it successfully for over thirty years on everything from British, Japanese, American and Italian manufactured motorcycles.

Jason
Hi Jason, I am trying your method of leaving the pedal depressed overnight tonight. Hopefully tomorrow will prove all the haters wrong!
Thanks for the advise.
 
Hi Jason, I am trying your method of leaving the pedal depressed overnight tonight. Hopefully tomorrow will prove all the haters wrong!
Thanks for the advise.
I know this works well of front brakes as the master is higher than the caliper. I'm not sure you will get the same result on a rear brake. Please let us know if it works or not.
 
Hi Jason, I am trying your method of leaving the pedal depressed overnight tonight. Hopefully tomorrow will prove all the haters wrong!
Thanks for the advise.

Haters? Wow. You just got here and already…

Abusus non tollit usum.
 
Reposted again for those who wish to know how a professional mechanic, a.k.a. a "hater" :eek: does it...

FWIW: Caveat emptor.


The brake system was never designed to remain under operating pressure for 12 hours or more!

What you are doing is pressurizing the whole system continuously for hours upon hours, something it isn’t designed to do, forcing the check valve into the open position and relying on the fact that air bubbles rise to the highest point in a closed system. If the banjo bolt on the master cylinder or a loop in the line is in fact the highest point, then the air will never get removed this way.

I have repaired blown caliper piston seals, master cylinder seals, broken hydraulic fluid lines, ruptured banjo bolt seals and more from this wrong technique.

Suffice it to say that this is not how to do this correctly.

Most air in the brake lines comes from opening the bleed valve too much and allowing air past the threads of the bleed valve.

It is also caused by not having either continuous pressure from the lever or continuous vacuum being pulled on the bleed valve, before you open it up very slightly to allow the fluid to be forced through the tube under pressure, and the air along with it.

Yes, there are people who will say they do this zip tie on the brake lever with no problem. YMMV. (My point is that if a brake bleed is done correctly, this zip tie thing is unnecessary and prevents undue stress and potential damage on the system.)

I have a long list of people who will tell you that it was an expensive mistake.

-----------------------

I bleed brakes on motorcycles of every marque literally every other day or so.

I have never needed this “zip tie” method. It’s not the way you do this as I wrote above.

I certainly never “crack open” the banjo bolt on the master cylinder. That is just beyond bizarre and one would be very hard-pressed to explain the rational for this.

The process of bleeding brakes is very simple. It’s not magic. It’s engineering. All you are doing is ensuring that brake fluid fills the entire brake line with no trapped air. Air can be compressed and gives that spongy feeling in the lever. Brake fluid cannot be compressed, and when all air is purged from the line, the lever feels solid and firm.

So to do this:

1. Open master cylinder cap.

2. Using plastic syringe, I remove all contaminated fluid from the reservoir.

3. I utilize 3-4 cotton swabs held together to pat against the reservoir bottom and absorb any remaining debris or contaminants from inside the master cylinder reservoir, and I also gently swab out the master cylinder sight glass from inside the master cylinder with 1 single cotton swab because brown contamination usually is stuck on the inside of the sight glass window. (When you pull out the swab, you will see the brown or black debris on it which has been wiped from the inside of the sight glass window)

4. I remove all previous fluid from the master cylinder by patting these cotton swabs to absorb the fluid, HOWEVER be sure that you do not snag the cotton swabs in anything inside the reservoir, just pat them like a mop to absorb the contaminated fluid, and NEVER touch the brake lever with the reservoir empty! You can safely empty the reservoir to near dry condition by just patting the cotton swabs on the fluid at the bottom of the reservoir, so long as you do not touch the lever. This leaves the line full of fluid but no air enters!

5. Refill master cylinder with clean, fresh brake fluid. The reservoir will now be full of fluid that is absolutely clear in color.

5. I attach a long clear (~ 2.5’ length) tubing to the bleed screw by simply sliding it tightly over the nipple. (This is the trick in my estimation, because the 2.5' of line allows me to see the expelled fluid clearly and completely. Any bubbles will be easily visible and they are most likely coming from the air slipping past the threads of the bleed screw if it is opened too far. If you intentionally open the bleed screw too far, you will see how this happens. )The other end is inside of my waste fluid catch bottle. It does not need to be under brake fluid or anything like that. (We will observe a continuous flow of brake fluid through this tubing in a moment).

6. Crack open the bleed valve by turning counterclockwise with your wrench just to the point where you feel the screw break loose, then turn it back every so gently clockwise to just reseat it back closed but not tight.

6. Gently squeeze the brake lever a few times to establish a solid working pressure and while holding the brake lever in, turn your bleed screw back counterclockwise very slowly and ever so slightly until the lever begins to slowly and smoothly move inward, thereby expelling the brake fluid under pressure. The opening of the bleed valve is such that the resistance you are looking for in the hydraulic line when under pressure from the lever, is one of being slightly resistant but not free flowing. The lever should be collapsing slowly and uniformly as the fluid is pushed out the bleed nipple.

7. Once you find this point in the bleed valve, it then becomes a simple matter. With the bleed valve still in this slightly cracked open position, I continue to squeeze the brake lever smoothly and uniformly while observing the continuous stream of old brake fluid now passing through my plastic tubing. There will be no air bubbles anywhere. Just a smooth continuous line of brake fluid, passing through the tubing. (Do not let the master cylinder go empty!)

8. As the master cylinder begins to empty, I refill it again with fresh brake fluid and continue this bleeding process for 3 refills of the master cylinder. This ensures that all previous old fluid and any contaminants are pushed out the brake line and out the bleed nipple.

9. As I get through the 3rd refill of fresh brake fluid in the master cylinder, while gently and smoothly squeezing the brake lever, I close the bleed valve completely and snugly with my wrench. (Don’t crush it, just closed and a little more to tighten.). Upon squeezing the lever again a few times, you will find the pressure and resistance in the line to be very solid and firm. The line from the master cylinder to the bleed screw, is now full of nothing but fresh clean brake fluid.

10. Repeat the same process for each individual brake caliper attached to the master cylinder. (1 or 2 in the front). 1 in the rear (attached to the other master cylinder fluid reservoir).

I can do this process by myself without issue. Some people use an assistant and that is fine but unnecessary.

The secret here is tuning your amount of opening the bleed screw so that the fluid that is pushed out of the bleed nipple, is pushed out under light resistance and pressure. You should have to squeeze the lever and pressurize the system to push the fluid out of the line. If the brake lever just immediately and quickly moves all the way through its stroke, then the bleed valve is open too much. If it hardly moves or moves excessively slow, it’s not opened enough. Find the correct opening! You want that continuous but light back-pressure resistance against your squeezing of the brake lever. We want to expel the fluid out under pressure.

The plastic line also visually shows you the fluid being pushed through. You won’t see any bubbles if you have the bleed screw opened correctly. If it is too open, air will enter from the threads area.
 
Last edited:
Wow, thanks for that comprehensive run down. I meant no offense by the "hater" comment. I am at the point where there is no pressure in the system no matter how much I pump the pedal with the valve closed. That's why I was wondering if there might be a leaking gasket somewhere. I am def not a professional, and just started doing (well trying to do) my own motorcycle maintenance. I for sure was opening the bleeder valve too much given your description so maybe I just have a lot of air in the line? Thanks again for your advise.
 
If absolutely nothing comes out of the bleeding process, then more than likely, a solid contaminant has infiltrated the master cylinder.

I just finished the brake bleed on a 2014 BMW R1200RA last week. Inside of the front brake reservoir, was "yellow jello pudding" inside of the brake fluid (water and high pressure car wash soap!). In the rear reservoir, it had hardened to "yellow hard toffee". You could pull out chunks of it and crumble it in your hands! The customer was SHOCKED! He did not realize that the chemicals would react violently like this. Believe me, they do!

If this happens in your reservoir, and a hard piece gets down into the fluid tube or even worse, the piston on the master cylinder, only taking it off the motorcycle and completely cleaning it, will get this debris out of there.

Hopefully, nobody reading this will have contamination this bad but given people's love for high pressure car washes, (the worst thing you can do to your motorcycle aside from intentionally driving it off a cliff), somebody might be experiencing a physical line blockage from debris like this.

IMG_7966.webp
 
Reposted again for those who wish to know how a professional mechanic, a.k.a. a "hater" :eek: does it...

FWIW: Caveat emptor.


The brake system was never designed to remain under operating pressure for 12 hours or more!

What you are doing is pressurizing the whole system continuously for hours upon hours, something it isn’t designed to do, forcing the check valve into the open position and relying on the fact that air bubbles rise to the highest point in a closed system. If the banjo bolt on the master cylinder or a loop in the line is in fact the highest point, then the air will never get removed this way.

I have repaired blown caliper piston seals, master cylinder seals, broken hydraulic fluid lines, ruptured banjo bolt seals and more from this wrong technique.

Suffice it to say that this is not how to do this correctly.

Most air in the brake lines comes from opening the bleed valve too much and allowing air past the threads of the bleed valve.

It is also caused by not having either continuous pressure from the lever or continuous vacuum being pulled on the bleed valve, before you open it up very slightly to allow the fluid to be forced through the tube under pressure, and the air along with it.

Yes, there are people who will say they do this zip tie on the brake lever with no problem. YMMV. (My point is that if a brake bleed is done correctly, this zip tie thing is unnecessary and prevents undue stress and potential damage on the system.)

I have a long list of people who will tell you that it was an expensive mistake.

-----------------------

I bleed brakes on motorcycles of every marque literally every other day or so.

I have never needed this “zip tie” method. It’s not the way you do this as I wrote above.

I certainly never “crack open” the banjo bolt on the master cylinder. That is just beyond bizarre and one would be very hard-pressed to explain the rational for this.

The process of bleeding brakes is very simple. It’s not magic. It’s engineering. All you are doing is ensuring that brake fluid fills the entire brake line with no trapped air. Air can be compressed and gives that spongy feeling in the lever. Brake fluid cannot be compressed, and when all air is purged from the line, the lever feels solid and firm.

So to do this:

1. Open master cylinder cap.

2. Using plastic syringe, I remove all contaminated fluid from the reservoir.

3. I utilize 3-4 cotton swabs held together to pat against the reservoir bottom and absorb any remaining debris or contaminants from inside the master cylinder reservoir, and I also gently swab out the master cylinder sight glass from inside the master cylinder with 1 single cotton swab because brown contamination usually is stuck on the inside of the sight glass window. (When you pull out the swab, you will see the brown or black debris on it which has been wiped from the inside of the sight glass window)

4. I remove all previous fluid from the master cylinder by patting these cotton swabs to absorb the fluid, HOWEVER be sure that you do not snag the cotton swabs in anything inside the reservoir, just pat them like a mop to absorb the contaminated fluid, and NEVER touch the brake lever with the reservoir empty! You can safely empty the reservoir to near dry condition by just patting the cotton swabs on the fluid at the bottom of the reservoir, so long as you do not touch the lever. This leaves the line full of fluid but no air enters!

5. Refill master cylinder with clean, fresh brake fluid. The reservoir will now be full of fluid that is absolutely clear in color.

5. I attach a long clear (~ 2.5’ length) tubing to the bleed screw by simply sliding it tightly over the nipple. (This is the trick in my estimation, because the 2.5' of line allows me to see the expelled fluid clearly and completely. Any bubbles will be easily visible and they are most likely coming from the air slipping past the threads of the bleed screw if it is opened too far. If you intentionally open the bleed screw too far, you will see how this happens. )The other end is inside of my waste fluid catch bottle. It does not need to be under brake fluid or anything like that. (We will observe a continuous flow of brake fluid through this tubing in a moment).

6. Crack open the bleed valve by turning counterclockwise with your wrench just to the point where you feel the screw break loose, then turn it back every so gently clockwise to just reseat it back closed but not tight.

6. Gently squeeze the brake lever a few times to establish a solid working pressure and while holding the brake lever in, turn your bleed screw back counterclockwise very slowly and ever so slightly until the lever begins to slowly and smoothly move inward, thereby expelling the brake fluid under pressure. The opening of the bleed valve is such that the resistance you are looking for in the hydraulic line when under pressure from the lever, is one of being slightly resistant but not free flowing. The lever should be collapsing slowly and uniformly as the fluid is pushed out the bleed nipple.

7. Once you find this point in the bleed valve, it then becomes a simple matter. With the bleed valve still in this slightly cracked open position, I continue to squeeze the brake lever smoothly and uniformly while observing the continuous stream of old brake fluid now passing through my plastic tubing. There will be no air bubbles anywhere. Just a smooth continuous line of brake fluid, passing through the tubing. (Do not let the master cylinder go empty!)

8. As the master cylinder begins to empty, I refill it again with fresh brake fluid and continue this bleeding process for 3 refills of the master cylinder. This ensures that all previous old fluid and any contaminants are pushed out the brake line and out the bleed nipple.

9. As I get through the 3rd refill of fresh brake fluid in the master cylinder, while gently and smoothly squeezing the brake lever, I close the bleed valve completely and snugly with my wrench. (Don’t crush it, just closed and a little more to tighten.). Upon squeezing the lever again a few times, you will find the pressure and resistance in the line to be very solid and firm. The line from the master cylinder to the bleed screw, is now full of nothing but fresh clean brake fluid.

10. Repeat the same process for each individual brake caliper attached to the master cylinder. (1 or 2 in the front). 1 in the rear (attached to the other master cylinder fluid reservoir).

I can do this process by myself without issue. Some people use an assistant and that is fine but unnecessary.

The secret here is tuning your amount of opening the bleed screw so that the fluid that is pushed out of the bleed nipple, is pushed out under light resistance and pressure. You should have to squeeze the lever and pressurize the system to push the fluid out of the line. If the brake lever just immediately and quickly moves all the way through its stroke, then the bleed valve is open too much. If it hardly moves or moves excessively slow, it’s not opened enough. Find the correct opening! You want that continuous but light back-pressure resistance against your squeezing of the brake lever. We want to expel the fluid out under pressure.

The plastic line also visually shows you the fluid being pushed through. You won’t see any bubbles if you have the bleed screw opened correctly. If it is too open, air will enter from the threads area.
Dang… this guy knows how to do it!
 
Hi Jason, I am trying your method of leaving the pedal depressed overnight tonight. Hopefully tomorrow will prove all the haters wrong!
Thanks for the advise.
So, what were the results?

Jason
 
I have repaired blown caliper piston seals, master cylinder seals, broken hydraulic fluid lines, ruptured banjo bolt seals and more from this wrong technique.
I'm sorry Scott but you're wrong here.

Think about what you are saying.

You're essentially saying that the brake system cannot maintain a seal for any more time than it takes to brake/stop a motorcycle, a few seconds perhaps?

I've designed, tested, operated and maintained many hydraulic systems and they are not designed to leak if pressure is applied in excess of a few seconds.

Jason
 
I'm sorry Scott but you're wrong here.

Think about what you are saying.

You're essentially saying that the brake system cannot maintain a seal for any more time than it takes to brake/stop a motorcycle, a few seconds perhaps?

I've designed, tested, operated and maintained many hydraulic systems and they are not designed to leak if pressure is applied in excess of a few seconds.

Jason
But do hydraulic systems have a relief valve that lets that mechanically assisted pressure bleed off when the ram reaches the end of its travel - me guesses yes…
Not so with brakes…
 
But do hydraulic systems have a relief valve that lets that mechanically assisted pressure bleed off when the ram reaches the end of its travel - me guesses yes…
Not so with brakes…
So you're saying that your hand or foot pressure exceeds the sealing capacity of the brake system if applied for too long a period of time because there is no relief valve?

Jason
 
One other thing that helps: the line from the master cylinder to the ABS Module should go steadily up hill with no areas to entrap air. Likewise, the line from the ABS Module to the caliper should always aim down. I ran the front tire up on a 3” block and placed a 1-1/2” board under the kickstand. Bleed the rear brake with the bike on the side stand. The line crossing from right to left at the swing arm pivot will be going downhill.

Turn the rear caliper upside down, but do NOT raise it up high. Put a clear plastic line on the breather, and have this line go up higher than any brake component.

Pump pedal and monitor the bleed hose. When all air is gone, close bleeder.

It worked for me.

Fred
 
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