Master Cylinder Rebuild - DIY (2 Viewers)

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ClassyJalopy said:
Yes the whole assembly comes out without much fuss (held on by 4 bolts!) and then you can play with it on the bench. Once I replaced the booster motor and accumulator bottle, re attached to the ABS module and replaced the master cylinder piston. I semi-bled it on the bench (sitting in a container). And then just bled all 4 corners.
That got the brake pedal nice and firm.
From there on, I suppose I could try and activate the ABS but skidding on wet/soft surface and keep bleeding, but $129 fee felt like an affordable way to get it right.
Click to expand...
Ok so you did not bled the red line. Just 4 at the pump and at 4 wheels. Thanks.. confidence building... Ive done many master pumps but not this kind.
 
ClassyJalopy said:
Yes the whole assembly comes out without much fuss (held on by 4 bolts!) and then you can play with it on the bench. Once I replaced the booster motor and accumulator bottle, re attached to the ABS module and replaced the master cylinder piston. I semi-bled it on the bench (sitting in a container). And then just bled all 4 corners.
That got the brake pedal nice and firm.
From there on, I suppose I could try and activate the ABS but skidding on wet/soft surface and keep bleeding, but $129 fee felt like an affordable way to get it right.
Click to expand...
What tool did you use to remove the accumulator? Did you torque it to FSM spec during the install?
 
medtro said:
What tool did you use to remove the accumulator? Did you torque it to FSM spec during the install?
Click to expand...
The accumulator and motor are already in one unit.
 
Important! Check the reservoir after you bleed each wheel AND TOP IT OFF. The reservoir has weird multi-chamber / baffle system in it. You can go from looks good to sucking air in one wheel, and then you get to start all over again....
 
medtro said:
May be. It depends on what he bought.
Click to expand...
Yeah, I bought them all in one unit. This is what my old part looks like

20210905_124333.jpg
 
Ok, so you disconnect flexible fluid line, red hard fluid line and two wires? I might go this route. Thanks!
 
Posted this question in a separate thread...

2003 LC 100 w/245k miles. We have been having the ABS light/ Brake light/ alarm condition intermittently which causes the undrivable 'no brakes' condition. Being intermittent and not being able to replicate the condition has been very frustrating. Before I replace the MC or brakebooster etc could the wheel sensors be causing this 'zero brakes' condition? I was thinking the wheel sensors would only throw the ABS light and not the full blown undrivable no brakes condition. I didn't want to replace the big ticket items then find out in the end was just a bad wheel sensor...

I have been reading the various threads on ABS booster pump repair & replace and the MC rebuild DIY thread but from what I see the zero brake condition is either the MC or booster/accumulator.

Thanks in advance for any replies...
 
boze_man said:
Posted this question in a separate thread...

2003 LC 100 w/245k miles. We have been having the ABS light/ Brake light/ alarm condition intermittently which causes the undrivable 'no brakes' condition. Being intermittent and not being able to replicate the condition has been very frustrating. Before I replace the MC or brakebooster etc could the wheel sensors be causing this 'zero brakes' condition? I was thinking the wheel sensors would only throw the ABS light and not the full blown undrivable no brakes condition. I didn't want to replace the big ticket items then find out in the end was just a bad wheel sensor...

I have been reading the various threads on ABS booster pump repair & replace and the MC rebuild DIY thread but from what I see the zero brake condition is either the MC or booster/accumulator.

Thanks in advance for any replies...
Click to expand...
MC or booster. It has given you PLENTY of warning, sounds like. Fix it before you crash. Seriously.
 
gatormark91 said:
MC or booster. It has given you PLENTY of warning, sounds like. Fix it before you crash. Seriously.
Click to expand...

@gatormark91 is on it. You're dancing around the mileage where the pump fails. Especially if the truck has seen city mileage/stop and go traffic. The more you stop the more frequent that pump works in relation to mileage. Sounds like you are not in a pinch yet, but I do recommend finding a reputable mechanic to rebuild this pump or find a rebuilt for a good price. Don't end up like me on the side of the road having to pay $2500 for pump replacement from the dealer to get your DD back.
 
Last edited:
Thanks all who have replied...

Agree on the seriousness...re-reading my write up does make it seem like we driving daily and using strong leg muscles to bring 100 to a stop...LOL...we are not. When the condition occurred I found was wholly undrivable but after she sat for a couple weeks we went back to further diagnose and the condition was mysteriously gone and that when we very gingerly drove to local dealer. It was only after dealer could not replicate we drove home to ponder our next step when of course condition occurred on drive home so she parked once again...

Agree about the McGeorge price for whole unit...seems like a no-brainer...am getting a labor quote to replace the whole unit since the diff in price to the booster is too close to not consider...

Thanks again Bill
 
gatormark91 said:
MC or booster. It has given you PLENTY of warning, sounds like. Fix it before you crash. Seriously.
Click to expand...
Total brake failure, (Brake Pedal to the floor!) is a sign of no brake fluid pressure.

Either a leak, where all fluid lost. Which then pressure can't come back until system filled with fluid and bleed. Not common!

Or

The more common, brake booster pump motors commutator and or brushes failing. With commutator we get dead spots. Sometimes bushes land on dead spots of commutator, other times on good spot of commutator. Which we get intermittent brake booster run times. Soon motor will not run at all.

In 9 out of 10 bad commutators. I find the brake control wire corrosion. This is from brake fluid getting on brake control wires that run to motor from ABS black box, IMHO. Which increase resistance. Either brake fluid overfilled (very common) or silage, causes wires to get wet with brake fluid, which attract moisture.

If brake reservoir stained and dark brake fluid once flushed, fluid turns dark quickly again. You likely need the brake master also. Or within about a year. The increase pressure to nearly the day it came from factory, will reveal a bad O-ring/seal (screaming or squealing master with bubbles in reservoir). Which a new booster assembly will do, bring up pressure. Even a new brake control wire may.
 
hoser said:
For whatever reason, the new OEM Brake Booster Assembly is highly discounted right now. Will it go discontinued? I don't know. @OGBeno
$1317 @ McGeorge

47050-60043 - Brake Booster Assembly, With Master Cylinder 2003-2007 Toyota Land Cruiser | Ourisman Toyota Parts

Save Money On Your Brake Booster Assembly, With Master Cylinder (4705060043) For Your 2003-2007 Toyota Land Cruiser When You Shop With Ourisman Toyota Parts!
toyotaparts.mcgeorgetoyota.com toyotaparts.mcgeorgetoyota.com
Click to expand...
I'm a little confused on the pricing, because the list price seems low too for the whole assembly. A bunch of dealers have it listed at similar prices though. I'm not sure if I'm misremembering the price, or if there's a mistake in their system?
 
hoser said:
For whatever reason, the new OEM Brake Booster Assembly is highly discounted right now. Will it go discontinued? I don't know. @OGBeno
$1317 @ McGeorge

47050-60043 - Brake Booster Assembly, With Master Cylinder 2003-2007 Toyota Land Cruiser | Ourisman Toyota Parts

Save Money On Your Brake Booster Assembly, With Master Cylinder (4705060043) For Your 2003-2007 Toyota Land Cruiser When You Shop With Ourisman Toyota Parts!
toyotaparts.mcgeorgetoyota.com toyotaparts.mcgeorgetoyota.com
Click to expand...

What a dealer sells the parts for has no correlation with whether a part will go discontinued. No correlation at all.

:cheers:
 
@OGBeno Thanks, I asked because it was not just one dealer but a bunch of dealers that dropped their pricing.

Screen Shot 2022-01-19 at 9.20.08 AM.png
 
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