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Discussion Starter #1
Bench bled and installed an original rebuilt M/C, installed two new (AC Delco) rear wheel cylinders, brake shoes and brake lines. Bled rear brakes 2x each 'till all bubbles were gone and could see good fluid movement thru the hose, but the brakes are not working. I pulled the drum off and had my son press the pedal—nothing happens, the rear shoes don't move at all. I then bled right front caliper, and was going to bleed left front until I but ran into an immovable bleeder screw so I am stuck for right now. But that shouldn't affect the rear brakes, should it? I thought this would be "easier." I should know better by now. Anyone have a suggestion? Thanks.
 

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Method of bleeding?
Tryed cracking at the MC till a little fluid comes thru, then at the diff, then at the wheel

The bleeder that stuck...spray with CRC or wd40 several times over several days...purchase a new bleeder
Then carefully using a ring spanner try to remove...If not then remove the calipar , put in the vice..a block of wood on the top of the bleeder and wack 3 or 4 times with a big hammer bloody hard...it will the come loose....and replace it.
 

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a few ideas come to mind..
assuming your master is good, it could initaly bench bleed but not work due to bad bore or seals. maybe a combination valve issue?
try to power or vacuum bleed the brakes. re-bleed the master and then work your way back at each connection.

I'd try a those suggestions, if you can't get anywhere I'd get a new MC and start fresh.


Im posting the following from my personal experience and for reference only. I accept no responsibility for anybody burning their car up or garage down.

as far as your stuck bleeder I usually try a little heat,but only of your really good with a torch that is.I heat the bleeder with an acytelene torch until it's medium orange and then get the heat OFF it right away! then right after the bleeder is no longer any shade of orange I work it with a good tight fitting wrench whyle it is still good and hot.it may take a couple tries ,I dont rush or muscle it too much! I have had really good success with this many times but it takes skill. I keep a spray bottle FULL of water at arms length and pay ATTENTION !

keep us posted on what you do and what you find.

good luck!
 

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Discussion Starter #4
Thanks guys. I will get back in there and figure this out. I'll let you know what happens.
 

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Discussion Starter #5
Before I try the above suggestions…One more thing: The pedal would only go about half-way down when bleeding the rears, but when bleeding the fronts you could feel it hit that spot and then slowly go to the floor. Is that normal?

I've bled brakes before after replacing calipers, but not after replacing so many parts. Am I overlooking something? Or do you all think I'm just not finished bleeding the system?
 

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but when bleeding the fronts you could feel it hit that spot and then slowly go to the floor. Is that normal?
Is this with the bleeders closed?
If so no.
68zz

it could initaly bench bleed but not work due to bad bore or seals.
installed an original rebuilt M/C,
OK what do you call "rebuilt"
Bored out and reselieved with stainless OR honed out and new seals
The latter althu general practice 30/40 yrs ago is not so these days
An orginal MC will most proberly have been done sometime past in it history, and shouls only be done once...after that the tollerances will be to great.
Also the slightest imperfection, corrosion mark in the bore will cause your symtoms called fade.
If it has not been bored and reselved, get that done or put the "orginal away, and replace with a new unit.

I will lay odds that you have fade due to oil passing under pressure past the seals because of the above.
 

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a couple other causes of your inability to bleed the brakes come to mind. I have been a tech for a long time and seen many things in the dealership and shop. I have seen guys over-travel the master when bench bleeding thus damaging the seals in an otherwise GOOD master cyl. I have also seen quite a few NEW parts installed right out of the box only to be found faulty.

I always cringe when I hear that someone just installed a new part and is having issues.
 

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Before I try the above suggestions…One more thing: The pedal would only go about half-way down when bleeding the rears, but when bleeding the fronts you could feel it hit that spot and then slowly go to the floor. Is that normal?


no, this would make me suspect the master cyl.
 

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I just had the same problem after replacing the master cylinder and front calipers along with brake lines. The pedal would feel mushy the first few inches of travel and would only go to the floor when bleeding the front. I continued to bleed the rear lines even though I thought I was done a couple of times. Open one rear bleeder at a tim....put a line into a clear jar with enough brake fluid to submerse the line and keep pushing the pedal until all the air bubbles are gone and then push it a few more times but don't let the m/c run out of fluid like I did, then you have to start all over. That cured my problem.
 

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Discussion Starter #12
No…only replaced parts on the rear, other than the M/C. Thanks everyone. Unfortunately I must head out of town for a couple weeks. Don't know if I can get back on it 'till then. I was hoping to get thru with this before I left. Should have realized that it never goes as smoothly as you think it should.
 

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Discussion Starter #13
Bled and bled and bled, got more air out, and I'm finally getting some action at the rear brakes. I don't know if I am finished or not. I'm going to let it sit a few days and see if I get any more air. BUT, the pedal still won't go to the floor when bleeding the rears. Someone suggested the Proportioning valve may be acting up. What are the symptoms if there is a problem there? Why would that happen now? And are there options to fixing the problem short of repairing/replacing the valve? Thanks!
 

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I don't know if you got the front bleeder open but bleed all 4 thoroughly. Before condemning any parts as failed.
I wouldn't worry about the pedal not going to the floor when bleeding the rears. It is odd, but keep going.
 

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put car in the air.. make sure M/C is full... open all 4 bleeders and let it gravity bleed. just make sure you are there to check and re fill the master cylinder as the fluid goes down. woks like a charm.
 

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Discussion Starter #16
Thanks. I did get all four corners bled several times. I'll keep going, it does seem to be improving. Any thoughts on the Proportioning Valve getting "tripped" by pedal-bleeding the empty rear lines and wheel cylinders?
 
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