brake pedal going to the floor

[missionstreettattoo]

I put new wheel cylinders , new master cylinder, new lines, new shoes on, bled them, found two leaks, tightened the joints. see no leaks. push the pedal down it goes to the floor. if i pump a few times i get brakes. let it sit a minute or so and the same thing. I am at a loss now. I have looked on the back of the wheels to see if any fluid is leaking from the wheel cylinders inside and see none. any ideas guys?

[Mister-B]

Originally Posted by missionstreettattoo

I put new wheel cylinders , new master cylinder, new lines, new shoes on, bled them, found two leaks, tightened the joints. see no leaks. push the pedal down it goes to the floor. if i pump a few times i get brakes. let it sit a minute or so and the same thing. I am at a loss now. I have looked on the back of the wheels to see if any fluid is leaking from the wheel cylinders inside and see none. any ideas guys?

Did you properly bench bleed the MC before installing it? Are your shoes adjusted properly? Jack up the rear tires, and spin them with the truck in neutral and parking brake off. You should hear the shoes lightly making contact. Remove the rectangular plug from the back side. Insert a flathead brake adjustment tool and spin the adjuster a few turns at a time, spinning the tire each time to make sure. Do the same for the front wheels.
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[missionstreettattoo]

would any of these issues still cause the brake pedal to go to the floor?

[DT1]

Originally Posted by missionstreettattoo

would any of these issues still cause the brake pedal to go to the floor?

Yes. Bench bleed the M/C and perform the shoe run out per Mister-B's suggestion. When you do the bleeding, start at the wheel furthest from the M/C (rear passenger side) then rear driver side-front passenger side-front driver side. To be sure, repeat the bleeding procedure once again.
I use one of these...
http://motiveproducts.3dcartstores.c...it-_p_121.html

[missionstreettattoo]

i do not know what bench bleeding is. can you explain this please?

[Ironangel]

Failing to properly "bench bleed" the new master cylinder would cause a soft brake pedal...

[DT1]

Originally Posted by missionstreettattoo

i do not know what bench bleeding is. can you explain this please?

Take a look at this...
http://www.autozone.com/autozone/vid...earchType=byId

[PanelDeland]

Since it's already mounted,it's not so easy.You should have gotten a bench bleed kit with the MC.It is a couple of hoses that screw into the ports(brake line holes) on the MC.They may be soft hose and should be run into the reservoir of the MC.Then fill the MC with brake fluid and pump the brakes.You need to be sure the hose stays below the fluid level and pump until no air bubbles come when pumped.The hook up the brake lines and bleed the brakes.Normally this is done by pumping the MC with a screwdriver while it is clamped in a vise,which usually works better since you can get a full stroke on the MC which is not always the case when in the car.

[Mister-B]

Originally Posted by missionstreettattoo

i do not know what bench bleeding is. can you explain this please?

That's probably your problem then. Air in the MC.

Get yourself a vice. I bought one at harbor freight for $24. I clamped it to a stool, since I don't have a garage or work bench.

Run one line from the side plug back into the reservoir, and do the same for the other line (you can buy a bleeder kit for ten bucks). Fill the MC reservoir with fluid. Take a screw driver and push the pump in and out about an inch. Make sure the lines are covered with fluid. You'll see bubbles escape. Keep going slowly until no more bubbles appear, and you can see fluid go out and sort of splash up cleanly.

Take the MC to the truck, keeping it level and install it.

You might want to look up youtube clips to fill in the blanks if I've missed something
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[DT1]

BTW... in some cases you can get by without the bench bleed, but for me, a power bleeder is an absolute must. Not saying I can't do without but for the small investment, a power bleeder makes the job so easy, it's almost fun.

[Lee H]

The service manual has the procedures for bench bleeding and system bleeding (not farthest to nearest). The procedure also lets you know how to set up the proportioning value for bleeding.

[Mister-B]

Originally Posted by DT1

Yes. Bench bleed the M/C and perform the shoe run out per Mister-B's suggestion. When you do the bleeding, start at the wheel furthest from the M/C (rear passenger side) then rear driver side-front passenger side-front driver side. To be sure, repeat the bleeding procedure once again.
I use one of these...
http://motiveproducts.3dcartstores.c...it-_p_121.html

Good advice. On the passenger vs drivers thing though, I think (at least in my truck) the drivers side rear is farthest away from the MC, since the line runs from front to back, and then has further to travel to the drivers side. Is that what you see?
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[missionstreettattoo]

thanks guys!!!

[Ironangel]

Heres a link explaining the procedure... http://www.superchevy.com/technical/.../0509sc_bench/ ...I replaced my MC last winter and the new MC came with plastic plugs and instructions how to bench bleed the MC...The procedure is also outlined in the service manual...Good Luck

[missionstreettattoo]

well i tried to bleed the mc. drained half the fluid out, re bled the lines. still see no leaks and still straight to the floor

[Mister-B]

Originally Posted by missionstreettattoo

well i tried to bleed the mc. drained half the fluid out, re bled the lines. still see no leaks and still straight to the floor

You removed the MC to bench bleed it?

Did you check your brake shoes like I mentioned?

How exactly are you bleeding the brakes?
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