dumb brake bleeding question

[jocko]

correction - MASTER CYL bleeding question....

So, I've always bled masters by putting short lines from the outlet ports looping back up into the reservoirs and pumpin about 1" slowly repeatedly til no bubbles showed.

However, the master I am currently workin on came with plastic screw-in caps that are supposed to be used for mc bleeding. So, it says to install them, then do the same 1" slow pumping til bubbles are gone.

Anyone ever used the plastic caps that plug the ports to bleed their master cyls? I'm not quite sure how this works, but apparently it does...

Thoughts? Thanks.

[BMERDOC]

The air will bleed through the feed holes in the bottom of the resevoir being replaced by fluid. Does the job.

[jocko]

Cool! thanks. I guess maybe I should actually follow the directions for a change. never thought of that.... (feed holes).

[k1rodeoboater]

It does indeed work...I still prefer the hoses though as it's easier to see you got all the air out. Plus if you use the hoses you can bleed it with the prop valve on.

[tomfg]

I tried bleeding my new dual master / booster combo today with the plastic plugs for the ports. Pumped the pedal slowly until I was blue in the face, and it still won't pump up. Had the wife come out after supper and push the brake pedal while I watched in the MC reservoir, and I do see movement, so the piston must be moving.
I have plently of slop in the brake pedal adjustment rod, so the MC plunger should be coming back all the way, I would think.
Tomorrow I'll try draining some brake fluid out of the ports that currently have the plastic plugs, and if that doesn't work, maybe I can rig up some short brake lines back to the reservoir, or a jar, and see what happens.

Any other suggestions???
Thanks.

[padresag]

Originally Posted by tomfg

I tried bleeding my new dual master / booster combo today with the plastic plugs for the ports. Pumped the pedal slowly until I was blue in the face, and it still won't pump up. Had the wife come out after supper and push the brake pedal while I watched in the MC reservoir, and I do see movement, so the piston must be moving.
I have plently of slop in the brake pedal adjustment rod, so the MC plunger should be coming back all the way, I would think.
Tomorrow I'll try draining some brake fluid out of the ports that currently have the plastic plugs, and if that doesn't work, maybe I can rig up some short brake lines back to the reservoir, or a jar, and see what happens.

Any other suggestions???
Thanks.

make sure that you have the right length pushrod if you changed anything

ron

[tomfg]

Ron, The rod between the MC and booster is factory, as it was a new / rebuilt combo unit. I did have to make up a new rod from the pedal to the booster however. I left a little extra slop in the rod adjustment to make sure the MC pistons stroke back all the way, then I was going to adjust it to specs after I had bled the MC and had a "pedal". The bleeding instructions say to only stroke 3/4 to 1", and I'm pretty sure I'm moving the rod on the booster that much when pumping.
If all else fails, I could adjust the brake pedal rod tighter, and try some more.
Thanks, Tom

[tomfg]

UPDATE: I ended up taking the MC off the booster, and mounting a plunger rod in the vice, and doing the bleeding there while I watch. Instructions say to keep the MC level, but I would have been trying (just like when it was mounting on the truck), until the end of time. It appeared that the reservoir toward the front pretty much had the air out, but the back didn't. What finally worked, was to tip the MC down each time after stroking it, and tapping the end of the MC on the workbench. Then, when I stroked it again, I'd get more air bubbles out. It still took 15 to 20 minutes of repeating this, but finally the air went away, and the plunger would only go in about 1/16".
I remounted the MC, and I have good brake pedal now. Have to finish up the brake lines before I can try it out..... of course, I got the wrong size plug to that job :-(

[tomfg]

Final Update- Have power brakes now! After I bled the MC, and put it back on the truck, finished hooking up the lines, etc., I proceeded to bleed the lines. Pain in the _ _ _! Tried the old one man gravity bleeding at first, opening one wheel cylinder bleeder at a time, with a hose hooked up to the bleeder, going into a jar of brake fluid, so air wouldn't get back into the system. I'd pump the brake pedal as well, and did manage to move some fluid thru the system. But even after doing this to all wheel cylinders several times, I could NOT get the brake pedal to pump up. After lunch, I had my better half come out and pump the brake pedal, hold it down, etc., while I opened the bleeders. Did manage to move more air, but after going around bleeding each wheel twice, still no brake pedal ! Gave up, and hauled some firewood to the garage for an hour. Came back, started pumping the brake pedal by hand, and after a few minutes, felt some pedal........ more, more, and finally had good brake pedal, without further bleeding. Probably more air in the system, but I will let nature take it's course for now. Went for a test drive, and it sure is nice having power brakes! Thanks my story, and I'm sticking to it!

[protrash64]

I just went thru a whole brake bleeding experience. After going thru the system numerous times; finding some small leaks and checking everything about four times I still had a weird pedal feel. The brakes worked but felt weak and if I gave them one pump they worked great. Turned out I needed to adjust out my rear shoes to get them closer to the drums. They were adjusted initially but after stomping on the brakes and a few miles they needed this readjustment. I now have great pedal and the truck stops very well. Manual system, by the way. Something to check if you are finished with everything else.

[HEI451]

I use the "tilt the master ON the vehicle" method, it is the only way it works for me. It is as yo did above, mounted the master on the vehicle, connected the lines, removed the master from the booster/firewall, tilted it forward to get the bleed ports in the reservoir to their highest point, and watched the bubbles come out as I gently pump the push rod.

Of course, I've always been told I was an idiot, moron, half wit and other expressions of mis-knowledge when ever I outline the "tilt the master" method, including a topic right here, not a week ago, but, this method has NEVER NOT worked for me, NEVER. IN fact, it is the ONLY way to get Dot 5 fluids to bleed in a motorcycle system without getting the fluid aerated.

The main problems with the hose bench bleeding method is, when the hoses are removed to remount the master, the ports are opened back up to atmosphere, and AIR re-enters the piston/cylinder area, causing a loss of prime, and, the master will always be set level in the vise, which doesn't allow all the air to bleed from the piston/cylinder area through the bleed port(s). Tilting the master so the bleed port(s) are at the highest point, and then bleeding the air out via the bleed port, is the only sure fire way to get all the air out of the system.

[HEI451]

I use the "tilt the master ON the vehicle" method, it is the only way it works for me. It is as yo did above, mounted the master on the vehicle, connected the lines, removed the master from the booster/firewall, tilted it forward to get the bleed ports in the reservoir to their highest point, and watched the bubbles come out as I gently pump the push rod.

Of course, I've always been told I was an idiot, moron, half wit and other expressions of mis-knowledge when ever I outline the "tilt the master" method, including a topic right here, not a week ago, but, this method has NEVER NOT worked for me, NEVER. IN fact, it is the ONLY way to get Dot 5 fluids to bleed in a motorcycle system without getting the fluid aerated.

The main problems with the hose bench bleeding method is, when the hoses are removed to remount the master, the ports are opened back up to atmosphere, and AIR re-enters the piston/cylinder area, causing a loss of prime, and, the master will always be set level in the vise, which doesn't allow all the air to bleed from the piston/cylinder area through the bleed port(s). Tilting the master so the bleed port(s) are at the highest point, and then bleeding the air out via the bleed port, is the only sure fire way to get all the air out of the system.