Track Tac

Brakes not bleeding

patriot07 said:
So how do I get it bled in this situation? I'm getting nothing out of the back of the hose with the cylinder mounted/installed and the hose attached. I left the back end of the kart elevated all night and the reservoir level didn't drop at all....
Click to expand...
You need master cylinder higher than caliper. Ie. Front raised.
If you have it bench bled, you can remove hose at caliper and bleed hoses same way.
Or, as flattop says, use a syringe into the bleeders with the hose removed from master cylinder. Reconnect hose after air bubble disappear.
If brake rod is holding master cylinder partially engaged, unhook and bleed.

Make necessary changes to rod length or stops to correct this problem.
 
95 shaw said:
You need master cylinder higher than caliper. Ie. Front raised.
If you have it bench bled, you can remove hose at caliper and bleed hoses same way.
Or, as flattop says, use a syringe into the bleeders with the hose removed from master cylinder. Reconnect hose after air bubble disappear.
If brake rod is holding master cylinder partially engaged, unhook and bleed.

Make necessary changes to rod length or stops to correct this problem.
Click to expand...
Ok, I think I understand what you're saying. But even if I disconnect hose from cylinder and put a syringe on the bleeder, I'm going to have air at the cylinder/hose interface...how do I remove that once I reconnect if the bleeder doesn't allow fluid to flow from the cylinder to the hose? Is that typical or is that what you're saying to correct? I don't have a way to alter rod length...I could change the brake stops but it sure would look funny with the pedal facing half down...
 
First things first.

It is never going to work, no matter what, if master cylinder does not return all the way.

A small amount of air will also remain on the caliper. This can be bled out using the traditional method, once you get to that point.
Bottom line is fluid must flow freely to the reservoir in either direction with the brake pedal released for the system to work at all. You can try to shortcut it, but it will end in frustration.
I tried to find a good pic of how the fluid gets from the reservoir to the brake lines, but could not come up with anything that would not confuse more.
Of course, a picture is worth a thousand words as far as linkage and stops are concerned.
 
Last edited:
flattop1 said:
I always left everything connected .
Pump straight through bleeder into master cylinder .
Click to expand...
Ah, gotcha. I'll give that a go. Just wondering if I can't get fluid from the cylinder into the hose, how do I get it from the hose to the cylinder?
95 shaw said:
First things first.

It is never going to work, no matter what, if master cylinder does not return all the way.
Click to expand...
Thanks for the video...unfortunately I think I'm in bad shape then. I might try to take some pics and post here in the next few days to get more creative ideas on how to fix it.
 
So much bad information on this thread I can't believe it. First of all which master cylinder do you have MCP or ??
 
Pretty sure its a off road / yard kart type .
Might need a new cylinder or disassembly to find any issue with the master cylinder .
IE: stuck valve , torn cup or oring .
 
patriot07 said:
Ok, I think I understand what you're saying. But even if I disconnect hose from cylinder and put a syringe on the bleeder, I'm going to have air at the cylinder/hose interface...how do I remove that once I reconnect if the bleeder doesn't allow fluid to flow from the cylinder to the hose? Is that typical or is that what you're saying to correct? I don't have a way to alter rod length...I could change the brake stops but it sure would look funny with the pedal facing half down...
Click to expand...
Connect the line leave it just loose / just barley hand tight .
Pump fluid in at the same time either loosen or tighten the connection while fluid is coming out .
alternativly get as much air out and bleed at that connection .
If you have a semi hard pedal at that point .
bleed as usual .
 
This is just getting weirder. I disconnected the cylinder from the pedal and all of a sudden fluid started coming out of the reservoir as I cycled through this order - leave bleeder open, push cylinder in, close bleeder, let cylinder loose, repeat. Then after about half the reservoir was gone, it stopped working. I put my harbor freight bleeder kit on and it didn't pull anything through and reservoir still stopped moving. I think there is zero fluid in the line or caliper. Where should I get a syringe to start pumping fluid in from the bleeder? Would HF have something like that?
 
flattop1 said:
Connect the line leave it just loose / just barley hand tight .
Pump fluid in at the same time either loosen or tighten the connection while fluid is coming out .
alternativly get as much air out and bleed at that connection .
If you have a semi hard pedal at that point .
bleed as usual .
Click to expand...
That's true - I think I may disconnect line from cylinder and push from caliper into the line and it should be good enough to bleed like normal at that point.

Such a pain - I still don't know if the master cylinder would work...
 
Disconnect the line at the master cylinder. Push pedal all the way down and hold it. (You might need help for this deal). Fill cylinder. Release pedal so the master cylinder piston bore fills with the fluid you just put in. Take your thumb off the line whole it was plugging. Hit the pedal full stroke. Does fluid shoot out where the line was connected? If not the master cylinder isnt working. In easier ways you could assemble the brake, fill master cylinder etc. as if you were going to bleed it. Take the line off the caliper, pump the brake. Even if you dont see fluid shoot out you should at least be able to feel air coming out if the master cylinder.
 
Some where it appears your short cutting the process .
Posts 16-18 and 21 .
If it was working then stopped there must be forgien material in the Master .
Syringe at vet or farm store animal section .
By any chance was the brake rod reconnected ?
 
Last edited:
This is how we bleed our brakes while in the shop, video from my Youtube Channel. I also have a video on rebuilding the brake calipers and replacing pads and what we generally see go wrong with the brakes in our higher horsepower karts. Yea this is on a vintage kart, but it uses the same MCP brake system that is on my oval kart and actually has more Hp.
 
I have seen a one gallon pump up spayer used as well .
The bladder bleeder i have is almost too much trouble for a small system .
Tried a brand new pump oil can but the result and effort didn't pan out .
 
I am super, super lost...so many different ways to do it and almost none of them seem to work on my kart. RP - I'm not sure what you connected or to where in that video. I appreciate you trying to help, but I'm not sure how you use compressed air input to get the air out of a fluid system...perhaps you could explain?

As far as my kart:
I know I'm getting fluid out of the master cylinder with pedal disconnected because it was pulling from the reservoir and pumping out of the brake hose connection.

I know the line is clear because I blew air through it.

My next plan is to connect the line at the caliper and disconnect at the cylinder, and push fluid in from the caliper using a syringe. Once I get fluid out of the front end of the line, I'll know the line and caliper are full and I can connect the hose to the master cylinder and see if I can get the cylinder fully bled by pushing in fluid from the caliper end. If not I don't have a good plan. I know it won't bleed using the cylinder to push fluid through the caliper, even with the pedal disconnected and everything getting full travel. I'm super, super over this...but I really appreciate all the help.

Brad
 
Thats a solid plan . Racing karts have a fill plug on the master cylinder cap .
When its full of fluid and you fill the line adding air pushes on the fluid .
Air wont come out till its out of fluid .
Even though its supposed to be a new master cylinder it may be bad or not new .

Putting small hose on the bleeders to a small jar of brake fluid with them open .
Once you get it full may work for you . That way theres no chance of air entering the system through the bleeders .
 
patriot07 said:
I am super, super lost...so many different ways to do it and almost none of them seem to work on my kart. RP - I'm not sure what you connected or to where in that video. I appreciate you trying to help, but I'm not sure how you use compressed air input to get the air out of a fluid system...perhaps you could explain?

As far as my kart:
I know I'm getting fluid out of the master cylinder with pedal disconnected because it was pulling from the reservoir and pumping out of the brake hose connection.

I know the line is clear because I blew air through it.

My next plan is to connect the line at the caliper and disconnect at the cylinder, and push fluid in from the caliper using a syringe. Once I get fluid out of the front end of the line, I'll know the line and caliper are full and I can connect the hose to the master cylinder and see if I can get the cylinder fully bled by pushing in fluid from the caliper end. If not I don't have a good plan. I know it won't bleed using the cylinder to push fluid through the caliper, even with the pedal disconnected and everything getting full travel. I'm super, super over this...but I really appreciate all the help.

Brad
Click to expand...
So all we are doing is using an air compressor to pressurize the MCP master cylinder instead of using the brake pedal. Unscrew the master cylinder plug, fill up the master cylinder with brake fluid, screw the hose's adapter in where the master cylinder plug was removed, apply the pressure to the other end of the hose by pressing it onto the nozzle, open the bleeder, listen for it bleed the air as you will hear it if your compressor is not running, and close the bleeder. Remove the hose and adapter and refilll the master cylinder with fluid, do the other line, good to go. MCP has a bleeder kit that they sell, we'll use that at the track if we do not have a compressor, but it does not work anywhere near as quick and easily, and as others have said, they'll use like bladders to pressurize it. http://www.tsracing.com/Bleeder-Kit-for-MCP-and-Enginetics-Only-P6495.aspx

In this video we completely disassemble and rebuild the MCP brakes from another of my karts. In my big Hp twin engine kart, I'll completely wear out the MCP pistons in the calipers in a season and have destroyed their o-rings as well. If you don't have a good piston and o=ring combo, bleeding the brakes is not going to get you anywhere as the seal is shot. Hope that helps.
 
Made some progress. Pulled the line and filled it and the caliper using the syringe, re-attached and at least now when I press the brake, the calipers are moving and pushing against the rotor. Not enough force for braking yet, but I think I've exited the "get the system mostly filled with brake fluid" phase and entered the "get the last bit of air out of the system" phase. I'm going to try elevating the front of the kart overnight and see how it is in the morning. If that's no good, I'll disconnect the cylinder from the pedal again and try to push more fluid in from the caliper in to get the last bit of air out. That seems to be working best. These brakes don't have to be awesome - just have to be somewhat functional. Kids are going to be riding this on some trails on the 33 acres we own - this isn't a racing kart or anything of that nature.

Thanks again for all the help guys
 
You must log in or register to reply here.
Back
Top