Air in Master Cylinder ??

B

biglar

New member
I've owned my 2002 T4R for 4 years and 30,000 miles now and brake pedal has always been spongy, tho' it does stop fine. Recently I read of a pressure adapter someone built to pressurize the system by putting air pressure to the master cylinder, then bleeding the brakes. Sounded good, I have regulated nitrogen in shop so I built one. It worked fine - too good - got away from me and blew nitrogen thru the system.

Now I've had fits trying to get a solid pedal - keeping in mind that it always has been soft. I've run 2 liters of brake fluid thru it and at 1st I got enormous amounts of air at rear brakes with ignition on but engine not running. Now I get clean brake fluid but still spongy pedal, just as before.

I'm sure some air is still in master cylinder and local dealer agrees with me, but he wants nearly $200.00 to do it for me. I looked at that mess and really don't want to fool with removing it to bench bleed it and don't want to spend $200.00. Can't find anything definite on the 'net on bleeding m/c in car.

Keep in mind this is an '02 with the $1200.00 master cylinder and the pressure pump and whole 9 yards.

Where can I look or what can I do ?? Sure would appreciate any ideas.

Thanks Lar.
 
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you dont have to pull it out to bench bleed it just take off the 2 lines run little hoses up to the tank and pump the brakes. then you got to bleed the brakes. I ran into a problem like this once when replacing the master cylinder for my first time I ended up having no brakes at all
 
Thanks, but there's my problem. Which 2 lines ?? Hoses from where to where ?? Tank is what ??......fluid reservoir?? I'm familiar with normal, standard brake m/c's but this thing is totally new to me. I really need a step by step. Please ! ! !

Thanks again
 
I took a picture of it only to find my website down. There are 2 brake lines coming out of a round portion near the top and they run parallel down to the frame, then go to the front wheels.

Below and to the left are 2 more, 1 above the other and going into banjo fittings, then to the rear wheels.

I found Tresrios brake adjustment explanation from Feb 20, 2011 and followed it to the letter. No air anywhere. When I did the 20 pumps and wait for beep/pump run and then fill reservoir, no change, so I did it 5 or 6 times and now have a spongy pedal that stops just a little above the floor. Better but no cigar yet.

Please, guys - which tubes go where and what do you do with them ???
 
To "bench bleed" a MC on or off vehicle, you disconnect the 2 hard lines and connect 2 pieces of plastic tubing in their place. Then run the other ends back into the reservoir.
Then slowly pump the MC to cycle the fluid through, which should get the air out of the MC.

Then re-install the hard lines and re-bleed the entire system, including LSPV, in the proper order.

Must ABS systems require you to bleed with engine off, then running, then off.

AS for the method of bleeding with air pressure (aka power bleeding), you do it by applying about 15 psi to a vessel containing brake fluid, which connects the the MC reservoir via a special plate. You don't apply air (or nitrogen) directly to the MC.
Check Motive Products, I have one of theirs, works great if you know what you're doing.
 
You're not thinking of the '02. I've gone over this a lot more and traced the brake lines. There are 2 on the upper right side of the m/c, (looking back from the front of the car) close together vertically and each goes to a front wheel - and they Are separate.

The 2 on the left side of m/c are more widely spaced vertically, connect via a banjo fitting and each goes to a rear wheel - separately. I followed all 4 brake lines with flashlight, mirror and by touch. Each of the 4 brake lines goes from m/c to a separate wheel and there is NO LSVP. I double - triple - checked.

I built a pressure bleeder and pressurized the system to 15 psi when bleeding. I get no air from the wheel cylinders - and I did bleed it again yesterday - for the 4th or 5th time - over 3 liters of brake fluid now.

I've ordered the Russell speed bleeders and they should be here by the weekend.

I know how to de-pressurize the nitrogen reservoir that feeds the rear brakes, so won't spray brake fluid all over.......but I really need to know how to go about bleeding the air out of this master cylinder. Local parts shops can't even find listings for it and local dealer won't talk to me - unless I pay them ~$200 to do it for me.

I'm having trouble believing that no one on this forum knows how to bleed the master cylinder on my '02 Runner.

Lar.
 
biglar said:
I'm sure some air is still in master cylinder and local dealer agrees with me, but he wants nearly $200.00 to do it for me. I looked at that mess and really don't want to fool with removing it to bench bleed it and don't want to spend $200.00. Can't find anything definite on the 'net on bleeding m/c in car.

Keep in mind this is an '02 with the $1200.00 master cylinder and the pressure pump and whole 9 yards.

Where can I look or what can I do ?? Sure would appreciate any ideas.

Thanks Lar.
Click to expand...

I'm running into the same problem after completing the 231mm upgrade. I just can't get it to bleed right and I'm not that mechanically sound. I called my local Toyota dealer and they said they would do it for $129.00?

Good luck!
 
MY 01 is in the same boat

I switch to the tundra 199mm brakes and now the pedal is soft. No matter what I do I can't get it to firm up. Someone must be a tech that has a way to do this without having to go to the stealer.
 
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