Brake bleeding issues

[wage92]

So i got my brake lines all hooked up on my k5. Went to start manual bleeding...(I have a 14 bolt in the rear converted to disks) so i started in the rear passenger side. Had my dad pump up pedal and hold, then i broke bleeded and got nothing. repeated this for a while and the pedal wouldnt fade for him when i cracked it either. so i began to think there was a problem, began cracking the line further up and got all the way to the Master cylinder and i would crack it, a few drops of brake fluid would dribble out (mind you this is while he is holding pressure). the fronts bled fine and work great, but i cant get any pressure out of the rear of the MC...i broke the line right there and it just dribbles out even though hes holding the pedal down...does this mean its time for me to get a new MC?

 

[chvymudin3388]

That's what it's sounding like to me... Did you have brakes before this?

 

[wage92]

that i am not sure of, only drove the truck for a week before i ripped it apart, i had brakes, but not sure if i had rear brakes. They seemed a little weak to me, but i figured it was because of the large tires etc.

My dad is betting i never had rear brakes. good ones at least...

 

[cybrfire]

Had the same situation on my crew cab. This was with a brand new MC.

Had to pressure bleed them to cure the problem.

 

[diesel4me]

I've had to start up the engine to get power brakes to bleed right before..sometimes the booster wont allow a full stroke to the master or it needs 100% pressure or something,not sure why,but with it running it bled normally ,when before all i got was a hard pedal that wouldn't "drop" when my friend opened the bleeder..

 

[wage92]

hmm, well i cant start it yet, but im close. So maybe i will wait and see if that solves the issue, if not then i can try a different method of bleeding. Thanks for the comments guys

 

[brian wafer]

take master cylinder off and try bleeding in a vice. you can use a big screw driver too push pedal and your thumbs too block holes it can be messy that way. or make 2 pipes that loop back in brake fluid resevoir,and bleed by your self(no helper)! you will have to do this if you install a new master cylinder anyway.

 

[Highpsi]

Brian beat me to it with the post above, but was gonna say for sure pull the MC and bench bleed it.

I was looking for an image of the kit that I used when doing mine recently, a really simple little kit with plastic fittings and clear hose and stumbled upon this one from Pirate. Looks like a good idea for a DIY option, just use some old brake line and fittings and voila.

 

[paratrooper307]

Generally when you buy a new master it comes with a bench bleeding kit. I saved the one that came with mine in case I ever need to do it again.

 

[wage92]

this isnt a new MC though...would that matter? It was on the truck before and worked as far as i know (well the fronts did anyway)

 

[diesel4me]

I've had master cylinders that worked fine before I had to bleed the brakes,but after replacing a blown line , during the bleeding process the master cylinder "ruined" itself,because the piston in it usually rides in the same place all the time once its bled,and after awhile the bore can get corroded or rusted further down in the part of its bore that never gets worn or used...and when you push the pedal all the way to the floor,the crud in that part of the bore ends up tearing or comprimising the seal on the piston and ta-da...it now wont hold pressure or develop full pressure any more..

Thats another reason I like using a vacuum bleeder..

 

[Highpsi]

Generally when you buy a new master it comes with a bench bleeding kit. I saved the one that came with mine in case I ever need to do it again.

That's what one of my coworkers mentioned too when I asked to borrow his kit. But the MC I purchased from O'Reilly did not have a bleed kit in it. I think it was just a Dorman brand too, and from what I saw that's the typical replacement part these days. If there was another specific brand that came with a small kit, I'd have spent a few extra bucks just for it!

this isnt a new MC though...would that matter? It was on the truck before and worked as far as i know (well the fronts did anyway)

I'd still just try bench bleeding it. Regardless once you've got it off and the ports are wide open, you'll see if they both spew fluid out when you depress the cylinder.

 

[cybrfire]

Never really understood the idea of doing the "bench bleeding" on a bench.

Put a new one in the truck and route the bleed kit or short lines back in to the res and pump it with the pedal. What's the difference. If your rig runs, let the vaccum booster help you do the pushing. Besides that, now you don't have to spill brake fluid when you move the master cylinder from the bench to the truck.

 

[Fordum]

Actually "bench bleeding" includes doing it that way. The idea is to get the air out of the master before bleeding the rest of the system.

But, sometimes you actually need to do it off the truck. Master cylinders have all kinds of nooks and crannies that air can hide. To get it all out, you sometimes need to tilt and tap on it while bleeding it.

I've done it both ways.

 

[diesel4me]

I only bench bled a master cyl. once,in a vise....after I washed the brake fluid out of my eyes that squirted dead center in both of them on the first stroke,my brother told me bolting it to the truck and pumping the pedal works as well or better,(after he stopped LAUGHING!)....
...since then I have always done it with it bolted up instead...haven't had any problems doing it that way,at least on GM's..maybe some vehicles that have them mounted at an angle may have to be bled on the bench though..