IDriveChevy

iTrader: (5)

Hey everyone, I've been trying to figure out an issue with my brakes and why they won't properly bleed out. Before I LS1 swapped my car the brakes were strong and worked no problem (LT1 car with LS1 front and rear brakes). After the swap I had encountered a leaky master and a frozen slide pin, both of which were replaced.

I bled the fronts and it moves plenty of fluid like normal but the brakes seem to be sticking. I can press the brakes and get a normal front brake feel but the pads don't seem to release like normal. I was in stop and go traffic and they seemed to get to the point of very hot and squeaking, even on take off after I hadn't been on the brakes for 60 seconds. My front wheels were covered in brake dust after a day. With that being said, I cannot get the rears to move a normal amount of fluid. I spent hours trying different methods and I could barely get a dribble to come out of the back lines, and I find it hard to believe that there is that much air in the lines. I have basically 0 pressure at the top of the pedal until I feel it hit the front brakes.

I have a reman master from autozone on currently which bench bled just fine. I have ABS delete / line lock on my car if that matters.

Methods of bleeding I tried for the rear:
Pump and crack the lines
Gravity bleeding
MityVac
Air compressor vacuum on the lines

I even took the line off my proportioning valve for the rear brakes and it pushed a small amount of fluid with a pedal push, but not as much as I would have hoped for. I verified there was no leaks in the main line running to the rear by pulling vacuum on the caliper and having a gauge on the line in the front, it held vacuum no problem.

Am I wasting my time with bleeding? The only thing I can think of is my reman master is bad, swollen rubber brake lines, or one or more calipers is bad. I'm at a loss here and very open to ideas.

Chris Paveglio

iTrader: (2)

Perhaps there is a small piece of dirt in the MC rear line/fitting, like a piece of rubber from an o ring was pinched or came off? You'd have to take the MC apart to find if there is debris.

IDriveChevy

iTrader: (5)

Bump it up. The master was new from autozone so maybe it has debris? It seems like the front works fine and then hangs up while the rear barely gets any fluid at all. When you push the brakes the rear piston barely comes out and hardly any fluid was moved when I bled it. I can only think of the master being bad right out of the box. I ordered the motive power bleeder so I'll give that a shot before replacing the master again.

joecar

I was going to suggest a Motive Power Bleeder.

Spartan7

iTrader: (7)

Does the pedal slowly sink to the floor when you hold pressure on it (engine off)? Did the problem start after the new MC? Did you bench bleed it?

IDriveChevy

iTrader: (5)

No it stays firm, and yes it started after the new MC. I replaced it since the old one developed a leak from the rear in the process of LS swapping my car. Yes I used the supplied bench bleed kit that came with it before installing.

On a side note I noticed I had my calipers on the opposite sides of which they should be (bleeders are facing down) but I did not have issues with them bleeding out previously. I plan on trying the motive bleeder when it arrives today, and worst case I upgrade to CTS-v brakes with all new braided lines.

Spartan7

iTrader: (7)

I'd try bench bleeding the MC again, just to be safe. And you might as well fix your caliper orientation before bleeding the system again. I love my Motive bleeder, it works great for bleeding by yourself.

IDriveChevy

iTrader: (5)

I'll give that a shot. I bled everything again this weekend and while I was able to get more fluid to come out with the motive bleeder, the front calipers were still hanging up and the rears barely did anything. I'm going to point the finger at the MC now, or my brake lines (all rubber) are shot. Part of me wants to just order braided lines, warranty the MC, and put CTS-V Brakes on the front lol.

1 FMF

iTrader: (1)

this sounds like the pistons in those calipers are sticking, keeping the pads pushed against the rotor with significant force. i would consider getting new/reman'd front calipers. the problem you describe i can't see how it could be caused by the master cylinder or by the brake lines.

IDriveChevy

iTrader: (5)

I went ahead and warrantied the master since it was free to swap anyway, and replaced the front brakes since I think it was probably a combination. So I got new calipers and such I'm going to bleed them today and see how it does.

95wannabe

iTrader: (20)

I hope it works out for ya, but i went thru 3 Autozone mc's and I finally got fed up with them and bought one from NAPA. No problem since.
Each one seemed to have a different problem.

IDriveChevy

iTrader: (5)

I think it was the MC. I replaced all of my brake lines, and used my motive power bleeder again (which came damaged btw, so its kind of MacGyvered to hold pressure). This time I cracked the rear line and it drained my MC reservoir in two seconds haha. I was able to bleed all of my brakes in like half an hour and they feel great now!