brake bleeding problem with rear, MC bad?

[michael hurd]

Make sure that the rear brakes are adjusted up tight against the drums, otherwise, you will never get all the air out when trying to bleed manually via the pedal.

You can also try an old trick, hook a long vacuum hose from a bleeder screw to another vehicle's vacuum port. Start engine and the vacuum will draw fluid through the system. It may work better with a small amount of teflon tape around the threads. I haven't used T-tape, and used this method. If you have a clear vinyl hose, you can see the fluid starting to move towards the other vehicle. Shut the engine off before you suck in a lot of it.... it will start to run a bit rough.

Once you have fluid flowing out all the bleeders properly, then you can close the bleeders, fill the M/C, and start manually bleeding the brakes via the pedal. The objective is to simply move fluid through the system to get rid of any air pockets, not to bend the brake pedal ( I had a brother do that on one of his trucks haha... ) or break the booster off the firewall.

Don't let the master cylinder run dry at all.... keep a watchful eye on the fluid levels.

Tapping the calipers lightly with a small hammer between bleeding cycles can get rid of stubborn air pockets. Once you have solid fluid coming on each stroke, you should have a good pedal. Start the vehicle and take it for a short drive. ( carefully ) If after that, the top of the pedal feels a bit mushy, I would replace the master cylinder.... after all from Rock Auto, you are looking at around $ 20 or so. Hope that helps.

 

[michael hurd]

Swims... looks like you posted when I was typing up a reply. Sounds like the master cylinder is on it's way out. I would definitely swap that out, and bleed the brakes.

 

[1997chevydriver]

Normally in but when you have air in the rear lines it might push out like mine did.

On the other hand though with you disconnecting that and just trying it at the mc it sounds like the mc is bad

Sent from my N860 using Tapatalk 2

 

[Swims350]

yea same thing I'm thinking. As for bleeding brakes I got a hand vac. pump to use, but I usually just do 2 person. pump and bleed.

as for that valve it's in now but earlier when trying to pump and bleed it was out.

 

[Swims350]

finally got them to gravity bleed, no luck tho.

PS rear had tons of bubbles, no change grabbing the hose or moving the bleeder screw, never stopped, bleed over a quart thru it.

DS rear had no bubbles, if it had any I missed them, but everytime I looked, solid stream, bled over a quart or close to a quart thru it.

PS front had tons of bubbles, never stopped, same as rear, change to the hose or bleeder made no difference.

DS front had a bubble every once in awhile but i bled about half quart-3/4 quart thru both fronts.

Then I hit the PS rear again, no change, bled a MC tank full thru it again.

 

[DGA1]

Did you wrap the bleed screw threads with teflon tape?

 

[Swims350]

nope. I figured it wouldn't matter me trying to gravity bleed or not I'm pretty sure the mc is shot.

 

[BOTTLEDZ28]

Swim, I am dealing with the same exact issue. I blew a rear line and drove for a while and then let the truck sit for a few months until I got around to it. Then while bleeding I blew a couple more lines from constantly pushing the pedal in and out. I could never get a good hard pedal so I changed the leaking master and nothing changed. A lot of guys have complained the the majority of the over the shelf master cylinders are junk right out of the box so now Im on the fence on whether or not I should pull mine and try another. The 4WAL system on my 94 isnt helping me at all either. Guys keeping telling me to just keep bleeding and I gravity bled the rears this morning. I walked away for 5 minutes to take a leak and I came back to an empty master (front section). I filled it up again and continued to gravity bleed. Hopefully I didnt get more air into the rear lines. I will find out later today when I do the two man method again. This time I am only going to slowly pump once and then crack.

 

[DGA1]

I think AutoZone lifetime warranties their MCs for life. If you get the same thing with one of theirs, there is a chance that it's bad too, but you can take it back and they will exchange it without question.

 

[Swims350]

yea i figured mine out, MC is fine. I found some crap to plug both lines with, and the thing was hard instantly, and stayed that way.

I plug the rear line only and it does the same, plug the front line so the rear can work and it gets soft and travels all the way down. Same when both are open to work.

I heard my prop valve rest so I may be ok now, I just have to bleed the entire system, gotta have help to do so, so it has to wait for now.