Brake bleeding nightmare

Hello world.

69' Electra drums on all four. Rebuilt the whole brake system last year. New lines, master, booster, wheel cylinders, shoes you name it. Had trouble with a bad master to start with, could not get it to bleed. Got another and off we went.

Fast forward to a week ago. I was driving it one night and the pedal basically goes to the floor but stops just barely. I was able to unhook the lines right at the master and determine that the front half of the master went. I replaced the master with another of the same. Bench bled just fine. I've been fighting it ever since. I just cannot get a firm pedal. I've checked and rechecked each fitting and inspected it for leaks. I'm just at a loss as to what to try next.

I've tried gravity bleeding each corner, bleeding the front first then the rear and the reverse of that. I've got a vacuum bleeder and tried it. Had a friend in the car for the old two person method.

What am I missing or over looking?

 

with two person bleeding, I have learned that when the person in the car must slowly allow the pedal to return to rest. Also, that person should then give the pedal a couple of short pumps before u open u open the brake blled valve & he performing the pedal to the floor.

 

How I have always bled dual circuit all drum systems.

Start with the front left.

With the nipple loose/finger tight, a box end wrench, a tube, a jar, full can of fluid, and a pedal pusher.

Have the pedal pusher slowly push the pedal to the floor and hold, with the line open, then close the line and have the pedal pusher allow the pedal to return, then have them press and hold to the floor, as I open the line.

The point is to have pressure as the line is open and important that the line be closed before allowing the pedal to rise back to its natural return.

And no frantic pumping, that only cavitates and introduces foam/small air bubbles.

As you progress a few times, (keeping watch on the reservoir after each two bleeds, then move the to right front brake.

After you have seen most of the bubbles gone and clear fluid, move to the left rear, repeat, then to the right rear.

You should see dramatic stiffening of the pedal.

Then start at the front left and do the entire bleed again.

I was in aircraft maintenance and dealt with all sorts of bleeding operations with and without assisted hydraulic system test stands, engine runs etc. and have bled brakes on many cars and motorcycles, and hydraulic clutches as well.

Slow, patience and methodical works.

Pumping too fast, or allowing the pedal to rise with the bleeder open will un-bleed your brakes faster than anything but a chainsaw to the brake lines.

And you are moving air about 6-10 inches at a time in the line, so factor the number of open/close/pump cycles to move the fluid/air completely through the line to the cylinder/caliper.

You can also open the bleeder just a little to start flow and pump slowly, by yourself if you don't have a helper, but you will likely not remove every bit of the air.

 

Usually have to do this as a one man show. I'll use a piece of clear fish tank hose and a partially full bottle of fluid. Crack the bleeder, push the hose over the bleeder and insert the other end through a small hole in the top of the bottle and to the bottom, submerged in the fluid. after that its in the car slow complete pumps until I see no air in the tubing. Works first time around nearly everytime.

 

have you inspected the wheel cylinders leaks? how did you determine the master was no good? was it simply empty?

 

I'm doing mine tomorrow! New lines wheel cylinders, master! Hope I have good luck

 

the cardone remans are junk. every one I've used leaks after a few weeks. I've been buying brand new units with good luck. i can't remember the brand name off the top of my head.

 

After reading Jason's story I decided to send my original out to Apple Hydraulics and get it rebuilt.
Peace

 

So, did the OP, Derek, get the brakes working properly? I've always started with the right rear to bleed the brakes. Last time I couldn't get any 'pedal' on a power/drum car, I did the front brakes, then the rear. Finally got pedal. Must be a different procedure between drum & disc.

 

Since my helper no longer wants to hear "up" "down" "up""down" any more I went to a vacuum system. It sucks the fluid out the bleeder. Yes, there is some air sucked out around the bleeder threads when its open so I never get "no bubbles". I can't go by that. But it always seems to work, never any issues and always a hard pedal when I'm done. Its actually called a fluid extractor like this: http://www.tooldiscounter.com/ItemD...-ZdIj9Z2QuraVX3CoZkmJS6hB1WKt4hKxEaAjR58P8HAQ

 

Well guys I went at it yesterday again.

I checked the rod adjustment, used a digital caliper to measure distance inside master to distance of rod and figured in the +- 0.20 that you want,so that's all good.

I have been using the one man bleeding trick with the half filled fluid bottle with the hose in it. Doesn't seem to change anything.

I did follow what I found to be the correct procedure of starting LF, RF, LR, RR for bleeding and still nothing.

I'm not getting in bubbles out anymore like I did when I started but I am getting fluid moving.

Any chance it's a bad brake booster valve causing me all of the grief? And should I be bleeding with car running?

 

you might try a brake adjustment. if your shoes are gone then the pedal will be low. are you getting a good stream at all 4 corners?

 

Just got wife's '68 Nova SS out for summer. No brakes! Checked the master = rear bowl empty. Filled it. Pumped until I got pedal. Checked the fluid and it was down very little. Manual drum. Now we are going to check the system to see where fluid is going. I had a large piece of old, oily cardboard under it, so no 'tracing' it by where it's wet under car. We will be changing over to silicone fluid as well.

 

Being you have 4 wheel drum, that's what I was thinking.
Pedal "feel".. aka, a "firm" pedal comes from properly adjusted shoes.
A VERY light drag on the drums.
You will get no pressure, or pedal firmness, until those shoes contact the drum and are forced against the machined surface.
The firm "pedal feel" comes from the drums adjusted properly, even on disc/drum systems.

 

Check your carpet. I also read somewhere you have to purge out the system very thoroughly before switching to silicone. It's nice because it doesn't hurt anything it gets on.

 

My money says crappy reman MC but if that was the case you would have had a devil of a time bench bleeding it. Converting to/from DOT5 is not rocket science. The procedure for a good thorough bleed with a removal and bench bleed of the existing MC or replacement MC should be sufficient. While DOT5 has the benefit of not absorbing moisture and not killing paint it has wierd issues at high elevations and generally a less firm pedal feel than DOT3 or 4. Some of the newer semi-synthetic DOT4 fluids are supposed to be very good about not absorbing moisture very quickly but I don't know if they eat paint.

 

Hey Guys, don't count out the rubber hoses, as they get old they plug up as they disintegrate from age internally, been there done that on the '68 GS 400, '85 C10 and '86 GN.

 

True!!
Just did both fronts on my wifes Safari van.
They will exhibit STRANGE behavior when old/worn internally