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-   -   New master cylinder, not pumping fluid while trying to bleed (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/new-master-cylinder-not-pumping-fluid-while-trying-bleed-933897/)

need RX7 12-10-10 02:30 PM

New master cylinder, not pumping fluid while trying to bleed
 
I replaced my master cylinder today, and replaced all the bleeder screws with Russell Speed Bleeders. I topped off the master cylinder reservoir and tried pumping the brakes with the rear passenger bleeder open, nothing came out, no air or fluid. I tried opening all the bleeders and pumping away on the brake pedal, still nothing out of any of the bleeders after a few minutes. The level in the reservoir doesn't seem to be going down.

clokker 12-10-10 02:48 PM

Did you bench bleed it first?

Snowburn 12-10-10 02:51 PM

Bleed
 
The FSM is a little 'wishy-washy' on their description to bleed the system.
However, when replacing a master cylinder, it needs to be 'bench bled'

If it has not been bench bled Haynes says: To bleed the cylinder on the vehicle have an assistant pump the brake pedal several times, then hold the pedal to the floor. Loosen the fitting nut to allow air and fluid to escape. Repeat this procedure until the fluid is clear of air bubbles.

Bench bleed per haynes:
Bench bleed the master cylinder before installing it. Mount the master cylinder in a vise, with the jaws of the vise clamping on the mounting flange.
Attach a pair of master cylinder bleeder tubes to the outlet ports on the master cylinder. Submerge the tubes in the reservoir
Fill the reservoir
Slowly push the pistons into the MC (using a large phillips head screwdriver) Doing so will expell air from the unit
Do this until no more air
When removing the bleed tubes, install 'caps' so fluid doesn't leak/air enter

need RX7 12-10-10 02:53 PM


Originally Posted by clokker (Post 10360550)
Did you bench bleed it first?

I did not. Is it 100% necessary? If I sit there and pump the pedal for a long time and attempt to bleed the calipers normall, will it eventually work itself out?

clokker 12-10-10 03:20 PM

It might.

yudaya 12-11-10 03:10 AM

ive ruined far too many Mcs like that idk why...but whever i didnt "bench bleed" it i couldnt get good pedal.took it out bench bled it ..didnt help at all..swapped it out for a new one..bench bled.worked great

Derekcat 12-11-10 06:11 AM


Originally Posted by yudaya (Post 10361463)
ive ruined far too many Mcs like that idk why...but whever i didnt "bench bleed" it i couldnt get good pedal.took it out bench bled it ..didnt help at all..swapped it out for a new one..bench bled.worked great

uh-oh.. >_<

Black Knight RX7 FC3S 12-11-10 09:51 AM

always bench bleed a MC when installing it.
Air is easily trapped in them between the chamber and seals.

misterstyx69 12-11-10 12:39 PM

The reason they put the hoses back into the Reservoir is to make sure that there is no air in the
master's chambers that will give the Brakes that Soft pedal feel.
..........
Try this without taking the master off.
If you can find some clear tubing about the size of the Brake lines going out of the master,then stick the tubes in where the Brake lines connect(at the Master) ..then put them Into the Reservoir,so in essence they LOOP,when you pump fluid it goes back in,
The reason That I say "clear" tubing is so you can see if there is any air bubbles left.
Once no air has been established you can attach the Lines.
Open all the bleeders and Gravity feed the Brakes.(let the fluid run out onto rags or whatever.This shit is 'Not Environmentally Friendly").
Then you can start bleeding the brakes.
Start from the Furthest brake caliper (pass Rear) keep going ,then move your way to the Closest (dr Front).


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