How do you tell if Master Cylinder is going bad? (1 Viewer)

[custyota]

Before y'all roast me I used the search function and couldn't really find much on the above topic. Lots of rebuilding master cylinders and where to source parts.

Back Story: Took my 1999 (250k) to a Toyota dealership for an oil change, tire rotation/balance and a general look over. (something I usually do before a long trip) I get a call from the service advisor saying that I have no brakes and the tech almost ran into a car in the parking lot. Service Advisor said the master cylinder is bad and it will be $4100 to replace. I did notice that my brakes seemed a little soft but I've had no problems stopping. There are no lights or alarms on that I know of.

I'm picking the cruiser up today and taking it to another shop for a 2nd evaluation. Is there any self checks I can do? Anything I should look for?

Thanks in advance.

 

[CruiserIRL]

If there is any doubt, I'd just replace it. I did try and rebuild one and it lasted a few months then started failing again. It's cheap enough to buy a new one. But, I wouldn't have the dealership do it. If you aren't comfortable with doing it yourself, any shop would breeze through it for cheap.

 

[custyota]

If there is any doubt, I'd just replace it. I did try and rebuild one and it lasted a few months then started failing again. It's cheap enough to buy a new one. But, I wouldn't have the dealership do it. If you aren't comfortable with doing it yourself, any shop would breeze through it for cheap.

I found a Aisin Master Cylinder on Amazon for $800 bucks. I might just bite the bullet and do it.

 

[CruiserIRL]

If your master isn't super rusty, like mine was, it may be worth it to rebuild it. Call Cruiser Outfitters and ask what they suggest. Worst case, they could get you a new one. I order from them every chance I get.

 

[duggy]

There are 3 components to the brake master cylinder assembly. The ABS module, brake master cylinder, and the electric brake booster pump/accumlator. We have seen failures among these 3 pieces at various times depending on a 100 series mileage. The most common failure we are seeing is the electric brake booster assembly which fails to build the right amount of pressure in the allotted time, which can signal a buzzer/chime and dash lights. This can be replaced independent of the master cylinder/ABS module.

We have been replacing the whole assembly in a lot of cars, namely because of failures looming in the other 2 pieces of the assembly. Look to see if an independent shop can install the part at a cheaper cost if they provide master cylinder assembly. It's definitely an expensive piece, but my thought is to always replace the whole thing and be done with it.

 

[custyota]

There are 3 components to the brake master cylinder assembly. The ABS module, brake master cylinder, and the electric brake booster pump/accumlator. We have seen failures among these 3 pieces at various times depending on a 100 series mileage. The most common failure we are seeing is the electric brake booster assembly which fails to build the right amount of pressure in the allotted time, which can signal a buzzer/chime and dash lights. This can be replaced independent of the master cylinder/ABS module.

We have been replacing the whole assembly in a lot of cars, namely because of failures looming in the other 2 pieces of the assembly. Look to see if an independent shop can install the part at a cheaper cost if they provide master cylinder assembly. It's definitely an expensive piece, but my thought is to always replace the whole thing and be done with it.

Thanks for the info. I'm going to call a recomended shop in the San Diego area called San Diego Trux, they come highly recomended and the owners has owned multiple cruisers over the years.

Toyota Lexus Repair and Service Toyota Repair | San Diego, CA - San Diego Trux

I don't get how I drove it in and an hour later I don't have brakes. hmmm

 

[jfz80]

SD trux has a good rep....

good luck with the repair man. The electro booster failure has been documented to be all of a sudden sometimes without warning or give the chime a few to many times before failure. Best to be on the safe side but applaud your efforts hunting a fair deal on the service.

oh yeah..... drive safe with no brakes

 

[shoboat90]

Custyota

I'm really curious on how all this pans out. I live in Oceanside and have also heard great things about SD Trux. I've had my ABS, VSC Trac lights popping on/off periodically over the last few months on my 01 LC and was considering taking it down to them for diagnosis.

 

[custyota]

Custyota

I'm really curious on how all this pans out. I live in Oceanside and have also heard great things about SD Trux. I've had my ABS, VSC Trac lights popping on/off periodically over the last few months on my 01 LC and was considering taking it down to them for diagnosis.

I'll keep you posted. Should be picking up the cruiser from the crapership soon.

 

[lt1fire]

report back if there are actually no brakes or they have just gone soft and the dealership is over reacting.

It could just be a stuck or frozen caliper causing a very soft pedal like what is happening in my LS430. Lots of times dealerships will just automatically go with the MC.

Normally when the master starts to go bad it will show over time before going out completely.

My brakes went out completely when Andrea was driving but it was the electric motor and that was accompanied with a buzzer and a CEL. That was a pretty easy fix just $300 for the rebuilt part and a lot of swearing as I installed it while the MC was still on the truck.

 

[CloudCity]

I don't have a comment on the diagnosis but a Lexus dealer replaced my entire brake assembly (master, accumulator, control module) for $2,800 after I requested a discount, but it was only about $3,600 before that, so it sounds like your dealer is gouging you if they want more than a Lexus dealer did for mine. Seems like the standard discount is around 15% for most shops if you just ask for one.

 

[nissanh]

If there is any doubt, I'd just replace it. I did try and rebuild one and it lasted a few months then started failing again. It's cheap enough to buy a new one. But, I wouldn't have the dealership do it. If you aren't comfortable with doing it yourself, any shop would breeze through it for cheap.

Though I dont have any brake issues, I am approaching that costly 250K mile mark. Instead of being stranded with the brake issue, I feel like replacing it. If I buy the whole unit, is it just remove and replace like other brake master pumps? There are wire plugs to remove, 4 hydraulic brake lines to remove and unmount from the fire wall and install the new in the reverse order? Thanks

 

[CruiserIRL]

I'm not 100% familiar with the 100 series, but I'd bet is all replacement parts are present, the hardest part would be bleeding the system.

 

[nissanh]

The bleeding was fun in these trucks. When I did mine with the help of my daughter, I had the ignition on and asked her to step on the brake and I then crack open the bleeding nipple. It just shoot out the fluid at a pressure due to the force of running electric pump. When no bubbles are coming, I am done with that wheel.

 

[Atxrunner]

In the same boat and mine sounds like a screeching owl on cold starts in the morning but haven't had any other symptoms. My toyota dealership quoted me like $4k as well, but I am hunting around for ebay or amazon parts/options.

98 99 00 01 02 Land cruiser LX470 abs brake unit master cylinder booster motor | eBay

BOSCH BRAKE MASTER CYLINDER FOR TOYOTA LANDCRUISER 100 LEXUS LX470 W/O ABS | eBay

reman 98-07 LEXUS LX470 TOYOTA Landcruiser Brake HYDRO Booster ABS pump motor | eBay

btw I have 272k miles on mine

 

[nissanh]

Bosch is not for our trucks. Wish we had that master pump with a rear locker.
A shop in Cali is rebuilding the motor. I know some 3rd gen 4runner owners used their service and happy.

 

[UZJ100LC]

Wondering if anyone can help me figure something out. Still baselining my truck and going through old service records. About 50k miles ago the previous owner had the “power brake assist motor and accumulator” replaced. I am assuming this is the booster unit? Am I still at risk of the MC going out or is this the defective part that most people experience? And if so why is it that many are replacing the entire MC unit $$ instead of just this booster/accumulator unit?