Master Brake Cylinder Bleed-help!

[FLA60]

Relating to my 84 FJ60.
I just finished searching on bleeding the new replacement brake master and it seems that the opinions expressed on the forum match the manual, bench bleed the MC. I guess my question may sound quite stupid, but if the MC is out of the vehicle and being bled, how do you keep the thing from losing the brake fluid when you try to reinstall it
Is there a snowballs chance in H that I can successfully bleed the bugger while it's fully hooked up in the vehicle
Thanks.

 

[AfricanToy]

Good question!!! I too need to replace my MC and would like to know what procedure to follow.

 

[PurpleFJ62]

I would also like to know how. To you guys who are replacing your MC i have a question for you. Before you pulled it was your first pump very soft, than the ones after that more "normal", being nice and firm?

 

[S&S1stCruzer]

PurpleFJ62 - Yes, it would still stop but pedal feel was like 50% of travel before getting some stopping power.

I bought the bench bleed kit or m/c bleed kit form an auto parts store and just followed the instructions. I think I kept the house attached to the m/c fittings until the last possible moment, the quickly reattahced the metal lines to it.

Some one else my have a better technique. It wasn't has hard as I thought it would be. And yes it cleared up my soft pedal feel.

 

[Cruzerman]

My method may be totally wrong but I'll share it anyhow. I take out the old unit and mount the new unit. I then take two short pieces of old hard line with the flare nut / flare on one end and cut off on the other. Screwed the lines into the master cylinder and bend the other end around so it goes back into the reservoir. Fill it up with fluid. Give it several pump of the pedal. Refill. Pump. Unscrew piece of hard line and screw in real hard line. Bleed brakes. Done.

 

[FLA60]

Has anyone had any success

Has anybody every replaced their MC and successfully bled the system without first bleeding the MC?

 

[S&S1stCruzer]

FLA60 - theres alot of air in there, I was surprised. Cruzerman's method pretty much same as mine except he installed it and used old metal lines, I used plastic fittings and clear hose(you can see the air bubbles).

 

[agent orange]

Has anybody every replaced their MC and successfully bled the system without first bleeding the MC?

Youll never get all the air out of the MC, its the highest point in the system.

 

[FLA60]

Thanks all, I was hoping I wasn't gonna hear that.

I don't mind uninstalling the MC and bleeding it. Unfortunately though, the only way I was able to get the brake fittings onto the MC was to unscrew the brass MC fittings, then start it onto the old brake fittings, then screw the brass fittings back onto the MC and then tighten all of it. I'll just start all over again and then try to muscle those old worn fittings on after I've bled the danged thing.
The beach'll have to wait a bit longer this weekend.

 

[agent orange]

You may be able to do the trick with bending the hardlines into the resevoir and just pump the pedal, as long as you can bottom out the piston in the MC youre fine.

You can also put a plastic bag over the end of the MC, cover the holes with your fingers, and have someone inside pump, the pedal slowly. Its messy, but as long as you clean the MC up with some brake cleaner afterwards its fine.

 

[FLA60]

Thanks AO, I'll try the baggie today, if that doesn't work I'm heading down to the local NAPA to get some new brake lines and I'll use the old ones to bend into the reservoir.

 

[ellington12]

FLA60,

don't take the master out again...you can bleed it in the truck but you'll need a helper.

have someone man the pedal while you keep tabs on the MC. keep the reservoir full at all times and here's what you can do.

have your helper pump the brake pedal and then hold the pedal down. then crack open one of the lines at the MC; you'll see air/fluid come out. make sure your helper keeps pressure on the brake pedal. don't let your helper let up on the pedal until you've tightened the fitting at the MC. repeat this process for both lines until you get nothing but fluid coming out.

use a fender cover and you may want to lay down a bunch of rags under the MC for this can get quite messy. clean up any spilled brake fluid with water.

since you've got a helper, now's a good time to flush out the rest of your braking system.

 

[93561Cruiser]

Anyone tried bleeding backwards???

I bleed the brakes on my plane by forcing fluid up from the calipers to the master cylinder. I never have to pump the brakes that way. I'm going to finish the clutch install on my FJ62 today hopefully and plan on bleeding the clutch lines from the bottom up, I'll report on how well it works.

 

[FLA60]

Thanks for both your tips Ellington12 and 93561Cruiser. I like both those ideas, and am real intrigued about bleeding 'from the ground up'. What kind of pump are you using to feed from the calipers 93651Cruiser?

 

[93561Cruiser]

Thanks for both your tips Ellington12 and 93561Cruiser. I like both those ideas, and am real intrigued about bleeding 'from the ground up'. What kind of pump are you using to feed from the calipers 93651Cruiser?

There is a pump made for airplanes
http://www.aircraftspruce.com/pdf/2007Individual/Cat07237.pdf

I have also used an oil pump to bleed brakes. A couple bucks at an auto parts store plus a short length of clear tubing to make sure there is no bubbles.

I bleed the clutch yesterday with an old oil pump and it worked great. I backfilled until the fluid filled the master cylinder reservoir. No need to pump the clutch pedal at all.

Cam

 

[FLA60]

Success!!

Just wanted to report on my success in bleeding the brakes without actually pulling the master to bench bleed. Recall that I installed a brake booster and new master.

I loosened the front brake line fixture to the master and wrapped the master and part of that line in a baggie. Then I pumped the brakes to run some fluid out into the baggie. Tightened the fixture, then bled from driver rear, pass rear, drive front and pass front.
Thanks to Cruiserparts.net for the Brake Booster and to CruiserDan for the OEM Brake Master.
And, above all, THANKS to all the MUDders out there with suggestions.