ZJ Hydraulic Brakes - HELP - Can't Get Them to Bleed!!!!

[Role]

I have a ZJ master cylinder off a Vector Fox Go Kart. The master cylinder part # 41744..

I was able to obtain the manual and parts manual, but I'm not familiar with how to clean these and trouble shoot, I usually buy new ones. But I figure the only way to be great at something is to know and apply it, helps for future builds.

The master cylinder nor brake line were assembled on the go kart when I bought the junked out thing, he handed it all it to me. He said he removed the master cylinder because the reservoir was cracked and he ended up giving me the new reservoir that he never put on nor back on the kart.

I attached everything after cleaning any visible dirt out of master cylinder... Using dot 4 brake fluid.. Opened rubber bleeder and started pumping, held down, recapped. Waited a few mins, then opened rubber cap again and started pumping.. Literally no pressure build up. Im convinced its the master cylinder.

Can someone point me to a 3 or 4 minute video tutorial on this specific part break down and how to clean it, as well as what I could clean it out with.

Im thinking it could be a little clogged. The brake line I think is fine because I sprayed a little brake fluid in one end and waited for it on the other and it started to drip.

I stuck my finger and sealed off one end of the master cylinder and then blew in the shaft airway of the master cylinder and I could feel no air.

It's driving me nuts! I want to put it on tonight - I have yet to drive it because of the brakes. I took a few pictures.

If I do need to clean it, what could i use? I have some gumout choke carb cleaner. I figured that may work since its a volatile solvent and maybe just let it soak in it?

Also, am I missing any pieces that you can see? It all looks good to me. I think these master cylinders are discontinued because I couldn't find a part diagram for it.

Help is appreciated!!! Thanks

 

[OzFab]

Ok, I'm gonna try to talk you through the process:

First step, get yourself some brake cleaner.

In the end of the master cylinder there should be a circlip (snap ring). Once you remove it, the piston assembly should come out. Clean the bore of the master cylinder & piston assembly & check the seals/o rings.

Now, where the reservoir attaches you will see two holes; one large (the feeder) & a very small one (the return). If the return is blocked, the master cylinder won't work. You need to find a very thin wire or needle to clear it.

Once everything is checked, cleaned & reassembled, find yourself a bolt that screws in where the brake line goes & nip it up. Now clamp the master level in a vice, pour in a small amount of fluid &, using a phillips screwdriver or similar tool, slowly push the piston in; you should see bubbles around the feeder hole. Release the piston & repeat until you get a spray of fluid from the return; now the master is pressurised...

 

[Role]

I'll give it a try and see what happens. Which side has the snap ring? Side furthest from shaft needle?

 

[Metalbender]

this may sound stupid but have you tried using a mity-vac? I had the same problem last spring...bled brakes for days with no pressure, even tried gravity bleeding them...used a mity-vac and had rock solid brakes in under a hour...

 

[Role]

this may sound stupid but have you tried using a mity-vac? I had the same problem last spring...bled brakes for days with no pressure, even tried gravity bleeding them...used a mity-vac and had rock solid brakes in under a hour...

Where could I buy one locally?

 

[Metalbender]

Where could I buy one locally?

any auto parts store...Harbor freight has a comparable model as well...it pulls the air out of the system using vacuum...has a bunch of other uses as well...their about $45 or so...

 

[OzFab]

Which side has the snap ring? Side furthest from shaft needle?

The end the plunger attaches to; it's internal...

 

[Role]

The end the plunger attaches to; it's internal...

I wasn't able to locate a snap ring in the plunger side.. It just look like a tubular metal shell and that's it.

I tried a reverse bleed using a bottle hangin upside down and attaching it to the bleeder valve and no success with fluid showing up in the reservoir.

I detached the brake line and unscrewed from master cylinder and tried squeezing the bottle while its over the bleed valve and no fluid was getting through the brake caliper.. So I wanted to take it apart as clean it to see if something was stuck shut.

Does this metal bowl inside the caliper come off? I tried shooting air into the holes but it won't move.. Maybe seized up?

Im getting super frustrated with this. How do I detach it if it does jar lose? Attached some pics.

 

[Role]

Can anyone guide me on this??? I'm ready to get it done.. I don't know what to disassemble and clean and I don't want to break it

 

[OzFab]

Ok, if you can't disassemble the master, just clear the return hole & try bleeding it.

As for the caliper, yes, that silver bowl is the piston; with enough air pressure it will pop out but the hole where you're putting the air blower needs to seal; wrap a rag around the blower & then around the whole caliper, it could get messy...

 

[Role]

Ok, if you can't disassemble the master, just clear the return hole & try bleeding it.

As for the caliper, yes, that silver bowl is the piston; with enough air pressure it will pop out but the hole where you're putting the air blower needs to seal; wrap a rag around the blower & then around the whole caliper, it could get messy...

I tried using air to force the piston out and that did not work, so I put a grease gun on the caliper and it came out nice and slow. Heck of a mess to clean up afterwards but it did the trick.

Now what? Should I put some brake fluid inside the piston area before placing it back in?

Also, I didn't see a snap ring on the reservoir piece in the front inside the shaft.. It just looks like a bullet hollow bullet shell inside the walls? Look at the pics I posted originally.

Any help is appreciated!

 

[OzFab]

Do the same as if you were fitting a piston to an engine; a smear of oil on the bore & on the piston will help prevent damage to the seals as you fit the piston...

I hate to say it but, I told you so