Bleeding Hydraulic Brakes

[cuzn246]

After fixing everything I could, and having a couple of successful trial runs on my used Kinroad (?) buggy, I found that the brakes needed some work. I had tested the brake system while the entire buggy was still on jackstands; front brakes worked but not effectively, and there was no braking at the rear caliper. It was the same when driving. The Emergency brake cable has been removed (frozen solid).

Before asking my helper to come out to the shop to help bleed the brakes, I checked the three bleed valves to see if they were frozen. I was able to open them all with no major effort needed, started at the right rear, then right front, then left front. Nothing happened at the first two, but I got a small squirt of brake fluid from the left front when I opened it. I guess I shouldn't have done that, probably introduced more air into the system.

Now, starting at the left front to bleed, no amount of pumping will produce any results. Also tried the right front, nothing coming out. The pedal goes completely forward and bottoms out - no pressure build up. I drew out as much of the old fluid as I could from the master cylinder and refilled with new fluid - still no results. Absolutely no braking effect when driving.

I don't see how I can remove all three calipers, the hoses and the master cylinder intact from the buggy to work on a bench. Rather than trying to find and buy an expensive pressure bleeding tool system, is there another procedure I should try?

[x-bird]

with the system closed (bleed screws tight) does the brake pedal bottom out? if it does, can you tell if the piston inside the master is retracting after releasing the brake pedal? sound's like it's stuck at the end of the stroke.

[cuzn246]

With the system closed, the brake pedal does bottom out - no resistance and no pressure build up at all at the pedal. Sounds like I'll have to disassemble the master cylinder and check the piston(s).

[cuzn246]

I removed the plastic fluid reservoir and the two robber grommets underneath, cleaned it all out as best possible. Still no obvious pressure or suction on either piston entry, and the plungers are still bottoming out. I cannot tell if the pistons are moving or stuck.
I then removed the brake light switch from the side of the master cylinder; activated the brake pedal and some fluid came out. Holding a finger over that hole and pumping the pedal, I can feel pressure at that location. I have a picture/drawing of a similar master cylinder, but with no breakdown of internal parts.
I'm going to the nearest city and look at a pressure/vacuum bleeding tool, and if it appears it might work on this system I'll buy it.

Running out of ideas and options.

[x-bird]

are your lines good throughout? Any evidence one or more of them may have a leak?

[metalstudman1]

The ball bearing/valve from the reservoir into the master could be rusted closed- Since you have NO brakes at this point I'd use compressed air (low PSI to start) to flush/clean the whole system and start fresh. Leaving everything in place means you won't blow out a piston. I've put air in the master cylinder hole inside the fluid chamber or the brake light sending unit and free-d the resevoir ball.Crack a bleeder (attach a hose to catch fluid in something)and put air into the other end of the brake line is one method. I use a shop vac (any vac with a hose will work)to pull fluid through the lines- can or jar with a lid(clear is best), drill/cut a hole the size of the vac hose,cut/drill a hole the size of tubing(1/4" usually) from bleeder. Vac hose is kept at the lid, hose from bleeder is dropped to the bottom. Elevate the 1/4" hose leaving the bleeder to watch for fluid flow. Fill master, crack bleeder, turn on vac and let it pull fluid into jar/can.

[cuzn246]

X-Bird: all the brake lines appear fine, no leaks anywhere in the entire system. I made the trip to the big city and bought the vacuum bleed tool/system. It creates a vacuum but won't pull any fluid from the left front bleeder fitting. I tried it with the bleeder closed to build up vacuum, per instructions, then cracked the fitting = no results. I also tried it with the fitting cracked open, with no results. It is becoming more probable that something is blocked in the master cylinder.

Metalstudman1: I understand what you're suggesting, but not sure of the vac, lid, jar, hose, bleeder set up.
I do plan to trying to blow out some areas; to try the other suggestion, crack open a bleeder fitting, detach that brake line at the Master (?) and blow air back through the line toward the bleeder? Blowing air into the brake light sending unit will affect the piston on that side? Or the ball bearing valve? Or both?
Thank you gentlemen for your help; I really would like to stop this thing once I get 'er done.

[metalstudman1]

With the piston in the master cylinder still backed up by the plunger it won't blow out- again low PSI.
Here's a pic of the vac bleeder or suction rig. It works like a champ both ways, when blowing I had to tape the vac hose down. Best used when bleeding by yourself on stubborn calipers with trash in them to pull dirt out & when I want to extract old/bad brake fluid.

[cuzn246]

Well, I am at my wit's end. I invested in a hand pump/vacuum bleeding tool, couldn't get anything out of the bleeder valves. Disconnected all three brake lines and brake light sending unit from the master cylinder; blew air from each of the three bleeder valves back through the lines, got some discolored liquid from them but proved they are not plugged.

Removed the MC, cleaned it, all appears to function properly. I can get suction at the four outlets on the MC when depressing the two plungers. Tried to bench bleed the MC, and got fluid coming out of the four holes, not much, but definite. Put everything back together, and still cannot get fluid to and out of the wheel cylinders.

Questions:
1. Can the banjo fittings at the ends of the hoses be turned so that the holes in the bolts don't align to/with the cylinder(s), preventing the passage of air/fluid?
2. Can the two rubber grommets in the bottom of the MC block the little holes in the bottom of the reservoir, preventing fluid from going where it should?
3. Is there something else I'm missing?
4. Anyone interested in a Kinroad buggy with no brakes?

The front brakes worked, but not too effectively, before I first tried to bleed the system. Now I cannot build up any pedal pressure. The plungers and pistons in the MC work.

[satoys]

Have you verified the piston(s) at the caliper are moving ? Went through this whole bleeding process, very frustrated, then x-bird gave me a good tip. Take off the brake line at the caliper, and blow air in the hole there. Your caliper piston(s) should move freely. Mine took forever to move, and finally blew out. Found corrosion between the rubber seals in the chamber. Bought a new caliper, blew air in the hole before installing them, the slid out with ease. Here is my story... http://www.buggymasters.com/forum/showthread.php?t=2512

[x-bird]

re the banjo bolts---position will not affect flow through them--they're channeled all the way around.

if the caliper pistons are frozen fully retracted, it "may" cause the issue you're having. you can try blowing them out to check (not a bad idea with an older system anyway).

I haven't played with these buggy brakes at all, so i'm not sure exactly how the various fluid passages are oriented.

These are tiny tiny tiny systems compared to automotive brakes, try both of the following:
connect all your lines etc. then open all your bleeders and put the master's reservoir as high as you can. fill it and let it sit with the caliper bleeders open. if you don't get any fluid dripping out after an hour, try doing the same basic thing, but see if you can hook and seal your vacuum pump to the master reservoir and see if you can push the fluid through the system.

if neither of these produces results, remove the brake lines from the calipers and repeat either of the above. if you get fluid through, the issue is in the calipers. if you don't, its the lines or master.

[cuzn246]

satoys and x-bird:

thank you gentlemen. I have not confirmed that the pistons at a/the caliper(s) are actually moving; I have not removed any of the wheel brake calipers, just disconnected the hoses there. So far, I have been concentrating on the master cylinder. I just went out and loosened the 3 wheel bleed fittings, with the MC filled. I'll check in the morning for any fluid draining at the wheel fittings. If not, I plan to disconnect everything and start again by blowing out all the lines as well as possible; then try to ascertain if the MC pistons are actually moving; it may just be the two plungers/springs that are moving. I hope I can rig up something to avoid accidents and remove the circlips holding in the pistons/plungers to check there for problems.

Thank you again for all your patience and assistance.

[metalstudman1]

I truely understand your frustration-I bought a brand new master and I couldn't get any fluid out of the reservoir, tore it down, and everything looked new, struggled & struggled. made the vac jar, hooked up it up and pulled fluid (very little) through it .I know you didn't care for my vac system!! But your issue was how I came to use it!! The circlip in the master is pretty easy to remove and re-assemble in most master cylinders to verify that the rubber around the valve/piston is good, also this should expose the ball bearing/check valve for the reservoir. You might be able to soak the housing or spray penetrating oil to free it up.
When it comes to your calipers- you can simply pry the pistons open with a screw driver while they're still attached to the spindles, this may be all they need- if they don't/won't open up then pull everything apart for a good cleaning.
Can you take a pic of your master and post it? There may be another master that will work as the brake system doesn't care how it gets fluid or pressure to the calipers.

[cuzn246]

metalstudman1: no, I did like your vacuum set up; it looks like something I would make if I had thought of it. And I may yet.

I am going to try the 'pry the calipers apart with a screwdriver' next. Then back into the MC and rig up a clamp or something to keep the plunger(s) from flying out, and get into the pistons/chambers/o-rings/bearing. I bet there is a problem in there. I had to J&B Weld the plastic reservoir that had a small crack in it (which became larger and another appeared when I was pressing the sides of the little crack with my thumbnails to see if it flexed; it did!). It seems to be holding, at least until a new arrives. I just went out for pics of the MC, and there is no fluid leaking from any of the wheel cylinder bleeder fittings.

[metalstudman1]

Well the rust rings in the reservoir pretty much tell me the master has issues!!! I'll bet the crack in the reservoir let moisture in- brakes don't like water!!!!! The dual plungers is a new one for me- but there are many masters with 3 port,brake soleniod units that you could change too if needed.If worse comes to worse you could get just about any master and add a line distribution block.
When you press the pedal/plungers- does the master have backwash? fluid being pushed back into the reservoir?

[cuzn246]

No, when I pump the plungers, nothing happens to the fluid in the reservoir. That is with it all connected up; when I did it with just the MC in a vise, I was able to get 'some' fluid from the hose outlets and the light switch outlet. I'm nearly convinced the problem is in the MC. I hope I can safely disassemble, clean and lube it and its parts rather than have to order more parts and wait. I'm practicing my 'patience' attitude and trying not to rush. Thank you once more for your help.

[satoys]

Originally Posted by metalstudman1

When it comes to your calipers- you can simply pry the pistons open with a screw driver while they're still attached to the spindles, this may be all they need- if they don't/won't open up then pull everything apart for a good cleaning.

MSM1 -can you expand on this a little ? I want to know all the tricks ! I used adjustable pliers on my pistons the first time, I was so frustrated I decided it was ok to trash/break them just to see what was going on. I got them out, but they are rough a the very top, and I doubt I can use them again. I got a new caliper anyway, so these are now my "training" calipers.

[cuzn246]

I've got it all disconnected again. The rear caliper piston is frozen pretty hard; I'll try to disassemble and service it. The right front was partially frozen, but broke loose with air, while the left front was not frozen. All three lines are clear. I plan to go into the MC and see what needs servicing - o rings, ball bearing, etc. I may actually be making progress. Also plan to try to buy some replacement banjo fitting washers, figuring they need replacement routinely when taking hoses apart. While I'm at it, I probably should go into all three calipers just in case. What kind of lube is needed for the pistons, etc.?

[metalstudman1]

Glad to hear you're moving forward- banjo fitting washers generally don't go bad unless you've seen a leak or damage to them (the good ones are copper). Lubing the parts -brake fluid!!just wet the O-rings with fluid, (don't use anything that may contaminate the fluid while assembling).

[satoys]

Originally Posted by cuzn246

I've got it all disconnected again. The rear caliper piston is frozen pretty hard; I'll try to disassemble and service it. The right front was partially frozen, but broke loose with air, while the left front was not frozen. All three lines are clear. I plan to go into the MC and see what needs servicing - o rings, ball bearing, etc. I may actually be making progress. Also plan to try to buy some replacement banjo fitting washers, figuring they need replacement routinely when taking hoses apart. While I'm at it, I probably should go into all three calipers just in case. What kind of lube is needed for the pistons, etc.?

Progress ! That is where I was, bleeding till I bled, then finding the calipers were froze... mine is stopping much better now. I think x-bird said silicon (like used on pool pumps, etc.) for lube but I'll let him or someone else answer, I'm still new to this. I have had problems finding the flat orings/rubber washers, basically the parts to do a rebuild. Seems the usual approach is replace. If you find the parts, please let me know !

[x-bird]

a very light smear of silicone on the o-rings won't cause any issues, or as metal said, just lightly wet them with brake fluid. O-rings should be available at any generic hardware/auto parts store. bring your originals with you to compare with.

[cuzn246]

After this, I'll stop wasting forum space.

Everything appears functional, but nothing functions in this hydraulic brake system. All hoses are clear and pass air both ways. All three wheel cylinders pistons are moveable, maybe not as easy as they should be, but I'm not familiar with how easy they should move.

The two master cylinder plungers and rubber cup type fittings on each one look clean and not worn. With the MC on the bench, activating the plungers, one at a time, results in a little air being forced out when depressed, and pretty darn good vacuum when released.

I rigged up a vacuum system like Metalstudman1 suggested, hooked to my shop vac. I can get some bubbling fluid drawn out of the left front bleeder fitting, and the level in the MC went down during my first attempt - [after some of the following steps, I went back to it and again got a little bubbling at the valve, but the fluid leved did not go down in the MC]. I could not get a solid stream of air free fluid after quite a while sucking, so I closed that fitting and moved to the right front.

I could get no action. I again removed that cylinder and brake line, made sure the piston would activate by blowing air into the hose fitting. Still no results when sucking on the bleed valve. I even removed the hose again from the wheel cylinder and blew back through it toward the MC - I got air into the MC.

I tried the vacuum rig on the rear brake and got nothing. All the above is with the brake switch inserted into its receptacle in the MC.

All this has been done without trying to bench bleed the MC; I have no plugs for the MC hose openings and don't think I did a good job trying that earlier by holding my finger(s) over various openings.

Thanks again for all the help and suggestions from everyone here, it is really appreciated.

[satoys]

I took my caliper off and laid it on the ground overnight to let gravity do the work. I think that turned out to be the best method. I made sure to have the reservoir full and the bleed valve barely open. Don't give up, has to be something, once you find it you will say @$#%@%@@%, why didn't it see that ?

[x-bird]

Felt today was a good day to revisit this one. I just installed all new brakes on the mini shark, with the exception of the caliper. I inspected the caliper prior to the install and all is good (nearly new). Trying the gravity bleed method, i got a tiny dribble into the master after 45 minutes. I also disconnected the line at the caliper (reservoir open) and sucked on it and got a little more, but not much. So i broke out the mighty mac bleeder and gave it a whirl. using it connected to the opened bleeder screw didn't do much of anything. It wasn't until i got a fitting that i could thread in place of the bleeder screw and would hold vacuum in the pump system that i got it to work. What i think is that since it's such a small volume of fluid and small orifices throughout, any air leakage at the bleeder screw will negate the suction quicker than the fluid can flow. I pumped the life out of it while on the bleeder screw and got zip. with the fitting shown below put in place of the bleeder screw, i was able to pull 5-6 ounces through the system pretty quickly. I was getting 15-20 psi without any leakdown until i opened the reservoir lid. After closing the reservoir and removing the fitting and installing the bleeder, a couple traditional pump, crack it, close it runs took care of the last little bit of air that backflowed in during the changeover.

Also, the amount of fluid that moves through the system is again so slight, that i don't think it will "fill" the drain hose--it will still give a bubbling outflow even when all the air is out. if the outflow hose was quickly reduced to an ID diameter of about 1/8 or less, then i think you'd see a solid stream of fluid--or loop the hose above the caliper to create a filled section. otherwise, it'll look like you're pulling air through even when you're not.

[Bryce]

What kind of fitting is that and where did you get it? I have the same MC as you on my Carter Talon 150 and am having the same issues as you describe above. This thread has been very helpful.

Thanks,
Bryce

[x-bird]

the fitting came with the mighty vac kit that i have. You could cut off and drill out a bolt of the same thread size and use that--hook a clean tube to it and you could probably use lung power to suck the system full. i really think the little bit of air that escapes around the bleeder screw threads when doing these is the culprit causing all the difficulties i keep reading about--that and systems that have sat and rusted.

[Bryce]

Drilling a bolt is a great idea. I will give it a try.
Thanks
Bryce

[cuzn246]

I'm glad of the added comments on this topic. I have tried every technique and method previously recommended to no avail. I get almost the exact same symptoms and results as you, XMAN. Bubbles and some fluid but no braking action. My last few efforts were: disconnect the brake line(s) from the master, submerge that end in a container of fluid, and apply suction at the wheel fitting - tried it both with the hose end below the wheel, and then with it above. With it higher than the wheel, I got more fluid sucked into the wheel cylinder than when I did it with the hose end below the wheel, but still no braking action. Of course, I lost some of the prime in the master before I could reconnect the brake hose(s). BTW, this is a dual chamber Master Cylinder, with one chamber operating both front disks, and the other chamber handling the rear disk and the brake light switch.
Yesterday, I used the vacuum tool on the rear wheel cylinder, and voila! I got some brake action after sucking a combination of fluid and air. The machine is on jack stands with the wheels/tires and fenders off while I am dealing with this brake problem. Cranked the engine, put in gear, revved it up a little and the rear brake stopped the axle; not a good test, but an improvement.

Today, after giving up completely on this project, I was putting away all the tools and supplies - I glanced back through the instructions for the vac tool. Although it is not mentioned in the section on bleeding brakes, it can be modified to apply pressure. I redid the hose connections on the tool as directed, put fluid in the canister, snapped the rubber fitting on the bleeder valve at the left front wheel, pumped a little pressure, cracked the fitting, and immediately got a good stream of bubbles into the master cylinder reservoir. I continued, until the stream of air dwindled down to a small stream of almost frothy tiny bubbles, then a little more and only fluid was being pumped into the system. I immediately saw that the pads were all the way against the disk, then I applied the brake by hand and tried to turn that wheel hub. It was "BRAKED"! And so was the right front hub!

Now I realize this is not an adequate test of braking, no wheels, and on jack stands traveling ) mph, but it is the most positive thing that has happened in the last 10 days or so. I took a refreshment break, put on the wheels, got it off the jack stands, pushed out of the shop and fired 'er up. I have brakes. It seems like they are adequately firm, but probably have brake fluid on the pads and/or disks. After what I've been through, it's amazing that brake fluid doesn't cover this whole county. I drove it next door to my Mother's and it will stop; not perfectly, but I can stop. It may be a blessing that I don't have a place to drive it and really open it up.

Small orifices, not tight enough connections of bleeding/vacuum hoses on bleed fittings, poor bleeding techniques, accidents with containers of fluid, a combination of Black Magic and Voodoo, have all combined to make my life, and my wife's, miserable recently. I really appreciate all the help I have received from all of you out there.

[metalstudman1]

So glad you got some sanity again!!! Great that you stuck with it.

[satoys]

I bet you even smiled and felt like you had accomplished something... I know once I got brakes I did ! btw- I think this another symptom of BA (buggy addiction), getting satisfaction out of make these silly things working after they have been sitting in place trashed out for years.

[SYCARMS]

I have always found that pumping the brakes when a system has been opened to bleed only leads to frustration for this reason. When you pump the brakes several times the fluid will push past the air in system,since the volume of air is greater then fluid, therefore the air will move further back toward the master, the opposite of what you want. The proper method is to start with the furthest from master working toward the closest eg. rear, right ft. left ft.. With the master full, open the rear bleeder then depress the brake pedal to push out the air, close bleeder and let off pedal. Repeat this step until you get a stream of fluid from that bleeder then continue to the next wheel repeating until all brakes have been blead. Now you can start the process of pumping the pedal to completely bleed out all remaining air. By doing it as stated since the bleeder valve is open there is no pressure on that part of the system therefore the fluid remains at the back side of the air and pushes the air out of the system. Now in the second part where you pump the brakes to remove the remaining air, the pressure will somewhat push fluid past the air but not to the extent of when the air volume was greater then the fluid volume in the line. Since now you have in the line mostly fluid you will have greater fluid pressure to push out the remaining air in system when the bleeder is opened. Hope I have not confused anyone..Pressure bleeders are great for large systems such as big trucks ect or when only one person is available. I have done many atv's bikes and buggies muself for years now using this proven method and have never had a problem.

TOM

[mtbdudex]

Originally Posted by SYCARMS

I have always found that pumping the brakes when a system has been opened to bleed only leads to frustration for this reason. When you pump the brakes several times the fluid will push past the air in system,since the volume of air is greater then fluid, therefore the air will move further back toward the master, the opposite of what you want. The proper method is to start with the furthest from master working toward the closest eg. rear, right ft. left ft.. With the master full, open the rear bleeder then depress the brake pedal to push out the air, close bleeder and let off pedal. Repeat this step until you get a stream of fluid from that bleeder then continue to the next wheel repeating until all brakes have been blead. Now you can start the process of pumping the pedal to completely bleed out all remaining air. By doing it as stated since the bleeder valve is open there is no pressure on that part of the system therefore the fluid remains at the back side of the air and pushes the air out of the system. Now in the second part where you pump the brakes to remove the remaining air, the pressure will somewhat push fluid past the air but not to the extent of when the air volume was greater then the fluid volume in the line. Since now you have in the line mostly fluid you will have greater fluid pressure to push out the remaining air in system when the bleeder is opened. Hope I have not confused anyone..Pressure bleeders are great for large systems such as big trucks ect or when only one person is available. I have done many atv's bikes and buggies muself for years now using this proven method and have never had a problem.

TOM

Thx - I'm bleeding my brakes tomorrow, this was a helpful read
Mike R