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The first time I blead the master cylinder, I could only bleed the REAR-RIGHT and the FRONT-LEFT. The REAR-LEFT and FRONT-RIGHT hardly spews brake fluid to flush out the air.
So I blead the master cylinder a second time. This time, all four bleeder valves would hardly flush out the fluid to remove the air. The pedal remains spongy .
Is the master cylinderr the one at fault. It is a new master cylinder.
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I made absolutely sure that there were no bubbles in the two tubes after bench-bleeding the MC and that the piston was very firm. My helper and I pumped the brake pedal ten times per repetition for each wheel but the moment I release the bleeder valve screw, there were just insignificant trickles of fluid coming out of the orifice. The car is a 2006, 3.9L, V6 chevy monte carlo with all wheel ABS.
If you bench bled the master and still get nothing or small
amounts of fluid. Get another master cylinder. Is this a reman
or new?[quote=”SAlasco” post=79337]It’s a new one.[/quote]
Try to gravity bleed. Open the bleeder and see if fluid will
come out. If not new master. If you crack the line at the master
see if fluid shoots out when pedal is pressed. or crack
the line at the caliper and press the brake pedal to see if
fluid comes out.Try removing the bleed screw.you could have
junk blocking the port.Did you follow the instructions on the little paper sheet that came in the box? Of course not. Hardly anybody does. We’re just so excited to get this shiny new thing into place we don’t even SEE the sheet. Or we think it’s just going to be pages and pages of obvious cautions like “Don’t stick your tongue into the slicer.”
You need to “bench bleed” the master cylinder. They don’t tell you why. The Why is that many master cylinders end up mounted at a slight angle, and since air bubbles rise to the highest point, you often can’t bleed out all the air once the master cylinder is mounted. If you’ve already mounted it, you can “bench bleed” it in place by jacking up the front or rear of the vehicle until the master cylinder is level.
The problem might also be that you have a LOT of air in the lines, which will happen if you let a brake line sit unhooked for a while and the whole line bled out. The only cure for this is to get the big oversize bottle of brake fluid and TWO helpers, one to keep the master cylinder reservoir filled up, anther to push the brake pedal, and you at the bleed valve, tightening, saying “push”, opening it slightly, watching the clear tube for fluid and bubbles, then tightening it, and saying “UP” over and over, at each wheel in succession until you consistently get solid fluid and the person at the pedal reports a firm pedal.
Do NOT use one of those “one person” brake bleeding devices, the ones with a check-valve. They don’t work very well, quite often air bubbles will sneak back in through the bled screw threads. Even after you try to block that path by putting some goop on the threads. Tried it, failed. You need the two friends.
There can also be hard to remove air bubbles in the ABS manifold, sometimes you have to loosen a brake line at the manifold and put a shop rag around it and bleed from there.
What we have done:
1) Twice bled the master cylinder.
2) Gravity bleed———->-trickles of fluid to almost nothing
3) Cracked the line at the calipers———>same as (1) above
4) Bled the wheels using a one-man bleeder pump.
5) Bled the wheels using two-man method.
6) Swapped calipers at the back just to be sure it is not the calipers at fault.We have not tried removing the bleed screw. But even if we did, is it possible that all 4 ports are blocked, if at all ?
Prior to bench bleeding the MC for a second time, I filled the brake fluid reservoir full, pushed on the piston, and fluid squirted from both ports of the MC.
How could air possibly get into the ABS manifold ? Would I have inadvertently introduced air when I disconnected (and reconnected later on) the two MC fittings from the two cylinder ports ?
How do you bleed from the ABS manifold ?
First, see if your rear brake lines go to a proportioning valve that’s operated by the rear suspension. If you’ve jacked up the rear end, the valve can end up fully closed and you won’t get anything out the rear bleed valves. You have to use a bungee cord or something to hold the valve open. Even the dealer mechanics at the VW dealer don’t know this.
Next, throw away the one-person bleed thingy, it’s useless, for two reasons.
You need the friend, a good friend that is willing to sit through the tedious cycle of “UP”, DOWN, TELL me when the pedal is almost all the way down, okay, now up. Repeated 20 to 30 times. The sometimes mentioned method of pumping the brake pedal 10 times vigorously, I don’t see how that can do anything good. Sometimes slow and easy is the bet way.
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