brake bleeding issue

[Ccamut]

72 T

Just rebuilt calipers, replaced rubber hoses, bled the brakes with motive bleeder like I have done 100 times before, calipers bled just fine, held pressure, old fluid out last can of blue in. Checked the pedal and it goes to the floor, pumped it 100 times and no pedal.

what did I do?

is there no fluid in the master?

Stumped.

Thanks

[gsjohnson]

I had air I couldn't remove after rebuilding my calipers, although I had some pedal. Try gravity bleeding. Attach a clear hose to the bleeder screw and open the bleeder screw and you should see air bubbles slowly travel up the hose. Close the bleeder screw and then move to the next caliper. You may have to repeat the process again, but this worked for me.

[Merv]

There is a nice post on how to gravity bleeding on the Pelican Forum. Works well

[jameshtaylor]

Here you go.

Gravity Bleeding

Many of you, especially those with early less complicated cars, can bleed your brakes easily in less than 30 minutes without an assistant, without spending more than $5 on equipment, and without causing any undue stress on the master cylinder. My 73 911 lacks a hydraulic clutch so I don’t know if this procedure can be adapted for use with non-mechanical clutches.

You will need: brake fluid, six or seven feet of plastic tubing sized to fit snugly over the nipple on the brake caliper (mine uses 3/16” internal diameter tubing but check yours), and an appropriate small box wrench to open & close the bleed valve. (Sears has small 6 sided combo wrenches which are useful for recalcitrant cases; the bleed valves on my car are 7mm but some I believe are 8 or 9mm.)

Here’s the procedure: jack the car up, support it on jack stands or wood blocks, and pull the wheels so you can get at the calipers. Or do one wheel at a time if you want.
Loosen the brake fluid container cover in the trunk.
At the first wheel, fix the plastic tubing so it hangs straight down (from your garage roof or door or even a stick or spouse) to the caliper. Slide the box wrench over the nipple, slide the plastic tubing over the nipple, and open the nipple with the wrench.
Watch the fluid rise in the tubing until it reaches the height of the brake fluid reservoir in the car, maybe 15 inches. This will take 3-4 minutes. Tap the caliper a few times with a rubber hammer or block of wood if you want. Watch the tubing for bubbles, especially when you start. A flashlight held behind the tubing will reveal all. If the bubbles keep on coming after the level in the tube has risen 12-15 inches, close the nipple, remove the tubing, drain the fluid into a paper cup, and repeat. Assuming you are bubble free after 12-13 inches of fluid have drained, however, do this once; tighten the wrench, pull the tubing off while holding a cup to catch the fluid, and move on to the next wheel.
Do all four wheels, keeping an eye on the fluid reservoir and replenishing the brake fluid when it's down more than an inch.
You are done. Gravity has done all the work. You cannot damage your master cylinder with this technique, and you don’t need a helper (if you have a garage or a tree or can rig a stick to hang the tubing from.) The process should take you a maximum of 5 minutes per wheel once the car is up and the wheels are off.
Forget the idea that there are bubbles all thru your lines and that pressure will somehow push them out but not the fluid. A pressure bleeder only moves any bubbles and fluid thru the lines more quickly. But they travel together. So gravity will do the job perfectly if time isn’t the object.
Forget also the notion that the pressure generated by your brake bleeding kit will somehow give you a harder pedal. You can’t increase the pressure inside the system any more than gravity allows; if you could the fluid would compress when you applied the brakes and reduce their effectiveness.
This process works well because nearly all the bubbles generated by driving around and heating the brakes excessively are found at the very top of the caliper near the bleed valve…where they concentrate when generated by heat. (Any 5 year old child knows bubbles don’t move down in a liquid, so they don’t flow down to the bottom of the caliper then across the hard lines and back up to the master cylinder. If they did, they’d escape from the master cylinder reservoir into the atmosphere anyway.)
Depending on how much fluid you withdraw each time, you will find that the fluid is fully replaced every 10-15 bleedings. I track my car 5-6 times per year; bleeding pretty much replaces all the fluid over a couple of years, as recommended by many experts.

[Ccamut]

Love the expertise on this site, I'll give it a try. Thanks all for the help.

[300343]

I had the same problem Then I figured out I had the calipers upside oops.