How to bleed Master Cylinder?

[jheight84]

Hello Everybody!

I have only owned my T4r for a few months but have found everything on this site to be very helpful. I finally have something to write about because I cant find a solution searching the forum's.

Down to the point...
I replaced my front pads and bled my brakes after reading about the frozen caliper problem and I think I let air into the master cylinder. The brakes feel better with the new pads/fluid but now I have the brake pump kicking on every 2 minutes while driving and not only is it annoying, but I don't want to have to replace the master cylinder!
Now, I have read that certain scan tools can bleed the master cylinder($400+) or I can go to the dealer and have them re bleed the brakes... Has anyone come up with a solution to do this themselves?

 

[djlandkpl]

When you bleed the brakes, the key needs to be in the on position so the pump is running. I can't remember if it's for the rears only but if you let air into the system, you need to bleed all 4 tires.

 

[jheight84]

I had the key on for bleeding the brakes. I was just not paying enough attention and let the master cylinder get to low so I have air in it now. While I am driving, every 3rd or 4th time I touch the brakes I can feel the pump kick in... from what I have read that it because air is stuck in the master cylinder and cannot be bled out from the calipers.

 

[djlandkpl]

I looked up the procedure in the service manual.

This part covers bleeding the master cylinder.

a) Turn the ign switch to off. Depress the brake pedal more than 40 times. Hint: When a pressure supply system is released, reaction force becomes light and stroke becomes longer.

b) Turn the igntion switch to ON, check the pump stops after 30 to 40 sec.
If the pump does not stop repeat a and b until the pump stops.

c) With the igntion switch ON, depress the brake pedal more than 20 times.

Starting with the front right then left calipers. Then do the right and left rear.

Hope this helps.

 

[jheight84]

Well, I tried this procedure (and found it in the service manual) but got nowhere. From what I can tell, the missing "hand tester" actually operates the master cylinder in a certain way to bleed the air.
Guess its time to call the dealer and price it out...

 

[cabowally]

Below is the complete bleed procedure. A basic scan tool will not bleed the MC but software like AutoEnginuity will.

BLEEDING

NOTICE:

Wash off brake fluid immediately if it comes into contact with a painted surface.
If the brake pedal is depressed with the reservoir cap removed, then brake fluid will spatter.

HINT:

If any work is done on the brake system or if air in the brake lines is suspected, bleed the air from the system.
When bleeding, keep the amount of the fluid between the Min. and Max. lines on the reservoir.

FILL RESERVOIR WITH BRAKE FLUID Fluid: SAE J1703 or FMVSS NO. 116 DOT3
BLEED BRAKE BOOSTER W/ACCUMULATOR PUMP ASSEMBLY HINT: Perform this step only if the brake booster with accumulator pump assembly is removed and/or installed.

(a) Turn the ignition switch off, depress the brake pedal 20 times or more , and release the pressure from the accumulator.
(b) Fully depress the brake pedal 10 times .
(c) Turn the ignition switch to the ON position and start the brake booster pump.
(d) Make sure the pump operates for 8 to 14 seconds .
If the pump does not operate as specified, repeat steps (a) to (c) and recheck the operating time.



BLEED BRAKE LINE

(a) Front brake line
(1) Turn the ignition switch to the ON position and wait until the pump motor has stopped.
(2) Connect the vinyl tube to the brake caliper.
(3) Depress the brake pedal several times, then loosen the bleeder plug with the pedal held down.
(4) At the point when the fluid stops coming out, tighten the bleeder plug, then release the brake pedal.
Torque: 11 Nm (112 kgf/cm, 8 ft. lbs.)
(5) Repeat (3) and (4) until all the air in the fluid has been bled out.
(6) Repeat the above procedures to bleed the other brake line.



(b) Rear brake line
(1) Turn the ignition switch to the ON position and depress the brake pedal.
(2) Connect the vinyl tube to the brake caliper.
(3) Loosen the bleeder plug and release air.

HINT: Brake fluid is sent through the pump, so keep the brake pedal depressed until the air is completely bled out.

(4) When the air is completely bled out of the brake fluid through the bleeder plug, tighten the bleeder plug.
Torque: 11 Nm (112 kgf/cm, 8 ft. lbs.)
(5) Repeat the above procedures to bleed the other brake line.



BLEED MASTER CYLINDER SOLENOID HINT: Perform this step only if the master cylinder solenoid is removed and/or installed.

(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position.
(c) Select "ACTIVE TEST" mode on the intelligent tester.
(d) Connect the vinyl tube to the rear brake caliper.
(e) Loosen the bleeder plug.
(f) Select "SRMF & SRMR" to drive the solenoids and bleed air from the rear brake caliper.

NOTICE: Do not depress the brake pedal.

HINT:

Brake fluid is sent through the pump.
To protect the solenoids, the intelligent tester turns OFF automatically 2 seconds after every solenoid has been turned ON.

(g) Repeat step (f) until all the air in the brake fluid is bled out.
(h) When the air is completely bled out of the brake fluid through the bleeder plug, tighten the bleeder plug.
Torque: 11 Nm (112 kgf/cm, 8 ft. lbs.)
(i) Repeat the above procedures to bleed the other brake line.
(j) Turn the ignition switch off.
(k) Turn the ignition switch to the ON position.
(l) Clear DTC.

CHECK FLUID LEVEL IN RESERVOIR

 

[Dang1]

so what is the right way when u change the rear brakes so you dont have to bleed the brakes?
should you unscrew the screw on the caliper so when u compress the piston on the calliper it pushes the air out right away?

 

[djlandkpl]

so what is the right way when u change the rear brakes so you dont have to bleed the brakes?
should you unscrew the screw on the caliper so when u compress the piston on the calliper it pushes the air out right away?

You can push the piston back in without opening the bleeder valve. The fluid will go back into the reservoir.

 

[Dang1]

You can push the piston back in without opening the bleeder valve. The fluid will go back into the reservoir.

thanks
but do you open the your reservoir?
also when you changed your brakes, did you have to bleed your brakes?

if so
what tire should i bleed first/order the brake fluid goes?

 

[djlandkpl]

thanks
but do you open the your reservoir?
also when you changed your brakes, did you have to bleed your brakes?

if so
what tire should i bleed first/order the brake fluid goes?

Yes, leave the cap loose to let the air out. It won't be too much fluid. You should not need to bleed your brakes if you are just changing the pads.

 

[Dang1]

Yes, leave the cap loose to let the air out. It won't be too much fluid. You should not need to bleed your brakes if you are just changing the pads.

ok.thanks.
how many times did you change brakes by yourself?
iam goin to be changing my rear brake pads. should i change one side and pump the brakes or should i change both sides and then pump on them?

thanks for your time

 

[djlandkpl]

ok.thanks.
how many times did you change brakes by yourself?
iam goin to be changing my rear brake pads. should i change one side and pump the brakes or should i change both sides and then pump on them?

thanks for your time

I've been changing brakes for a long time. Change one side 100% before doing the other side so you have a reference if you get stuck. The rears are easy. It's probably 5 minutes a side.

Do both sides then start the truck. The booster pump will pressurize the braking system.

 

[Dang1]

I've been changing brakes for a long time. Change one side 100% before doing the other side so you have a reference if you get stuck. The rears are easy. It's probably 5 minutes a side.

Do both sides then start the truck. The booster pump will pressurize the braking system.

oh ok.

so when i start the truck up. should u pump the brakes right away or should i let it sit there for awhile?

thanks for the help

 

[djlandkpl]

oh ok.

so when i start the truck up. should u pump the brakes right away or should i let it sit there for awhile?

thanks for the help

You can pump as soon as you start it.

 

[dcx5000]

How do you release the pressure in the accumulator?

 

[m85476585]

How do you release the pressure in the accumulator?

This is how:

a) Turn the ign switch to off. Depress the brake pedal more than 40 times. Hint: When a pressure supply system is released, reaction force becomes light and stroke becomes longer.

note: This is an old thread

 

[Lester Lugnut]

I realize this is an old thread.

Throughout it, mention is made numerous times to a "Pump". Not the action of pumping, but a physical pump.

Are people referring to the ABS unit or some other part of the system and am I going to hear/feel its activation?

Thanks.

 

[earthrealm]

bkmkd