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Breaks hit the floor after complete bleed

T

THEMCGUIRE

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Hello all... Hope you all have a wonderful holiday.

So here I am in North NJ and the weather is so warm. Decided to try and finally fix the breaks now that the trans has been rebuilt to level 1 upgrades. $2200.00 with a 3 year warranty.

While the truck will stop, the break pedal is on the floor when it does. It takes a while to stop, you cannot stop on a manhole let alone a dime.

I tried bleeding and I broke the bleeder on my front caliper. So I bought new calipers. Bled the breaks with engine off they were tight. Started engine and they went to the floor.

The trans guy suggested that it was the master cylinder. Replaced that. Bench bleeding is a bitch without a vise.

Re-bled the breaks with engine off, they got tight. Started engine they went right to the floor.

I do not see any break fluid on the ground under the truck.

(A lot around the outside where I spilled it when the slippery bottle slipped out of my hand. lol)

Per the shop manual I bled passenger rear, driver rear, passenger front and finally driver front.

Any ideas ?
 
How are you bleeding? By pumping the pedal, pressured reservoir, vacuum pump? How much fluid have you put through it? It's not uncommon to have a MC fail when you do a lot of bleeding, but two in a row seems odd. That said, it's also possible to get a bad one from the store - especially remanufactured. It's the only part in the system that can lose pressure without losing fluid.

Chances are that you still have air and need to do more bleeding. But you have to make sure you aren't letting air in as you do it. Also, you can "bench bleed" with the MC mounted in the truck. Just hook up the bench bleed hoses instead of the brake lines. Then you can pump it with the pedal.
 
I never thought of bench bleeding in place, too late the MC is in.

I have a pump but I seem to have a leak in the capture bottle cap. It will not hold pressure so I have been having my son pump the brakes as I open the bleeder screw with a hose running into a bottle with the end of the hose in some break fluid.

I bought a brand new A/C Delco MC. I heard that re-builts have problems.

The bleeders for the front caliper are on the sides but they appear to be near where the top of the cylinders are. The rears are quite high as well.

When I was doing the front I got nice clear fluid out. So I know that I got fluid from the new MC. The rear there was still a bit of darkness to the fluid.

In all I bled about 32 oz (1 large bottle of fluid)

I started thinking, could it be part of the power assist ? With the truck off the breaks got nice and firm and then when I started the truck they got mushy.

Now I should point out that this truck has been sitting since 2009. I just rebuilt the body. The thread for this is "WTF do I do now - 1988 Blazer".

Anyway, when I was spraying the frame after sandblasting it I disconnected the rear brake lines from the connector so I would not get the Rust Bullet paint on it. I don't know why I felt I had to disconnect it. However at this point is has been re-assembled and I do not have any brake fluid leaks under the truck.
 
You might want to look at your bleed procedure. Traditionally you start off at the wheel farthest from the master cylinder and go progressively closer. I used a vacuum bleeder, but for some reason I was still getting a spongy pedal. I couldn't get the front brakes to bleed well through it, so I bought some one-way speed bleeder screws and that did the trick. Unless the system is bone dry, you shouldn't need to run a whole quart through it. If all else fails you may want to take it by a shop and have them do a pressure bleed on it.

Also, make sure your brakes are adjusted right. I worked on a buddy's truck that had scary braking, and found that the rear shoes were adjusted all the way in, and the thick/thin shoes were not mounted properly. :rolleyes: You'll also want to check to make sure your wheel cylinders aren't leaking and that everything is connected properly.

It'll stiffen up when the truck is off because you have no assist. The power assist is working properly because it makes the leak or air in the system more evident because you are exerting more force with the vacuum assist.
 
Now that you mention it the self adjusting rear drums do not have holes to allow for manual adjustment of the breaks. (no knock out plugs either)

When I examined the rear brakes I found that the adjusting knob was almost touching the rear shoe. Since the brakes were almost new I figured this was normal. I had installed the new shoes myself back in 2008 when the truck was a DD and they worked fine back then until it sat for these last 5 years.

I am now wondering if something is askew with the power break assist. Sure would like a definitive answer about that possibility.

I am trying to figure out how to make a power bleeder at this point. All the examples on utube use a screw on MC cap. Mine is the rectangular cap. I am going to see if the cap from the old MC will fit.

If it does then I will drill a hole in it and the rubber gasket inside, attach some kind of port to let fluid in and zip tie it onto the MC body. Then I can attach my Mityvac and pump up the pressure to force the fluid from the MC to the valves at each wheel.

Anyone have any idea if this will work ?
 
If the booster fails, you will have no assist. Your pedal will feel just like the truck is off. Maybe if you doubled the vacuum to the booster (? that would be something like 38"?) you'd end up with "too much" assist, but that isn't going to happen, since engine vacuum governs booster assist on the non hydroboost systems.
 
ok so it is not the assist. Heading over to Lowes to see if I can find what I need to make my own power bleeder using my mityvac (set on pressure rather than vacuum.

Thanks
 
I have never used a vacuum bleeder and have successfully bled breaks many times.

I always use speed bleeders.

To me, it sounds like something isn't working or something is leaking. The fronts on these trucks bleed easy. The backs can get some air stuck in the line and require more effort.

Are you doing this alone? I have always considered this a two man job.
 
After using speed bleeders I won't go back. Much quicker and easier if you are doing it by yourself. You can get a set of four for less money than a entry level vacuum bleeder. I have a mityvac that creates a vacuum and sucks the fluid through the bleeder. It works, but a little cumberson to use.

There are some benefits to having an extra person around, mainly in that you can see the fluid as it comes out and know when all the bubbles are out and that line is good to go.
 
They are on the wall at auto zone :dunno:

I think they are a "help" part
 
Whenever I go to buy them I grab a few sizes and return them on my next trip. if you can bring an old bleeder with you that works too.
 
THEMCGUIRE said:
ok so it is not the assist. Heading over to Lowes to see if I can find what I need to make my own power bleeder using my mityvac (set on pressure rather than vacuum.

Thanks
Click to expand...
To build a pressure bleeder, just find an extra cap for your MC and rig an air fitting to it. IMO, the downside here is that brake fluid likes to soak up moisture, so you need a really dry source of air to pressure bleed.

To build a vacuum bleeder, just get a mason jar or something similar that can hold pressure and put two fittings in the lid - one for the hose and one for vacuum. The vacuum hose should just pass through the lid, while the fluid hose would ideally come near the bottom of the jar. For vacuum, you can use a cheap Harbor Freight A/C pump (venturi ~$20) and shop air or run the line up to your intake manifold. A 5.7L vacuum pump is no slouch.

You just hook up, crack the bleeder and keep the reservoir topped off.
 
Final Report

I gave up. Trying to use that mighty vac did not work. So I brought it to a local garage.

He tells me that I installed the replacement calipers on backwards. I did not know you could do that. When I was done installing them I had the bleeders pointing to the read. (Pretty sure anyway).

Whatever, he got them bled. The truck stops now :)).

Thanks to all for help and support.
 
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