Brake Master Cylinder Leak

[cabowally]

Hi guys:

Been around here off and on for stuff with the wife’s 2003 4R and like the Tundra and Land Cruiser forums you guys rock. I hate to jump in with a problem but after searching through 250+ posts and not seeing anything, I’m hoping someone has got some experience with this.

The parking brake indicator light started coming on intermittently on Sunday and by yesterday morning it was full on. A quick look at fluid reservoir showed it was low and that there was/is a leak coming out of the front of the cylinder assy between where the front right and left brake lines thread into the unit.




The rig is in Mexico so we ran it over to our local brake guy and he checked everything out and said it leaks but it’s ok because I filled it up and the light is off. My friends, that in Mexico is a 100%-satisfied –customer-repair job. What’s the big deal? Brake fluid is cheap and no one really cares about the paint anyway.

So here is my question: I haven’t found a single reference to this issue, nor does alldatadiy’s manual address this part in their repair guide. The leak is coming from the plug in the photos. It looks to have notches in it to un-screw it from the housing—I can’t see any other way to get it out. Does anyone know if it’s possible to pull this thing out and replace an o-ring (or something?) to fix this vs. having to go the $1200 new cylinder route???

Thanks a ton.

 

[M@M]

Bumping this thread, OP never found a solution, so I am wondering if anybody else has come across this!
First time poster, long time lurker. Learned a hell of a lot about my runner around here.

 

[e304runner]

Same Problem, same year

I had the same problem start on my 2003 V8 4x4 this last week. Flickering light which i thought was due to e-brake, only to find ou that my fluid has been leaking out and running down to the front left wheel well. Does anyone know whats going on here??? Help please.

 

[earthrealm]

[MENTION=93315]e304runner[/MENTION], i had a similar issue, ended up being a leaking brake line, replaced the brake line, bled the brakes n refilled the brake reservoir,and truck is good now

 

[e304runner]

[MENTION=78511]earthrealm[/MENTION] I will be taking some stuff apart (covers and what not) to try and better locate what exactly is leaking tonight. Where was the culprit located (more specifically) on your 4runner?

 

[earthrealm]

the culprit was the metal brake line that enters the caliper, u should be able to see it when you remove the tyre

 

[M@M]

Mine ended up being failure with the MC itself. Sadly I was unable to find a solution outside of replacing the entire unit with a brand new one from the dealer. Sorry to be the bearer of bad news! The new unit I believe is a superseded part number, and is readily available at several dealers, including ones which are vendors on this forum. So far so good with the new one.

 

[e304runner]

What did yours look like @m@m . I.e. where was fluid coming from? I'm going to attach some photos now that I have had a chance to look closer. My fluid seems to be developing behind the Black plate that says "Aisin" on it. Removed the outer cover and fluid was all over the lower 2 torx screws. The main plastic piece that has a bunch of ball bearings and wire connectors was very clean. I think this may be where/how the dealer bleeds the system. Funny thing is I had my car into the dealer for impartial flush and bleed a 6 months ago and now this happens... Curious. Anyone offer insight?

 

[ProjectV8Runner]

Brake fluid leak

Hi. So did you ever fix the leak from the master brake cylinder?

 

[e304runner]

NO, mine evetually stopped leaking on its own. After about 5 to 10k. I suspect is was caused by a piece of shit, (technical term) getting stuck behind one of the bleed orofices. But thats sut a guess. Hell, I dont even know if the dealer open thats to bleed the brakes. It could all be accomplished at the OBDII port for all I know. But in any case, it resolved itself, which to me, means something stuck behind an opening that can close and open, and it was dislodged. Maybe try activating the descent control and traction control on a slick road to engage all the systems that have control over the braking system. Might flush the particle through. However, thisdoesnt really answe the question, because if it was just internal, it wouldnt leak externally. Which circles me backt o my initial hypothesis that is comes from the bleed procedure. Mine done at the dealer. Hope that helps.

 

[dgbull3]

Before posting my own thread, I searched the forum and found this one...I have the same issue as the original poster, but without any lights coming on. I just finished replacing the motor/pump/accumulator assembly (motor fried) on my master cylinder unit. While bleeding the brakes, I was watching the MC and noticed a small dab of fluid appear at the leak point the OP noted. The fluid would only appear when the brake was pressed down, and it would go back in when the brake pedal was released. I'm guessing this has been happening for awhile because my plunger is much more rusty than in OP's photo. Question becomes....is this normal? (I'm assuming not, but wanted to ask) What are long term affects? Mushy brakes? Before replacing my accumulator assembly, I noticed my brakes have always been strongest after an initial light push on the pedal.

Anyways, does this point to needing to replace the master cylinder itself? thanks!

 

[dalandshark]

Before posting my own thread, I searched the forum and found this one...I have the same issue as the original poster, but without any lights coming on. I just finished replacing the motor/pump/accumulator assembly (motor fried) on my master cylinder unit. While bleeding the brakes, I was watching the MC and noticed a small dab of fluid appear at the leak point the OP noted. The fluid would only appear when the brake was pressed down, and it would go back in when the brake pedal was released. I'm guessing this has been happening for awhile because my plunger is much more rusty than in OP's photo. Question becomes....is this normal? (I'm assuming not, but wanted to ask) What are long term affects? Mushy brakes? Before replacing my accumulator assembly, I noticed my brakes have always been strongest after an initial light push on the pedal.

Anyways, does this point to needing to replace the master cylinder itself? thanks!

There is a way to rebuild that valve... I lost the link to the procedure, but you might be able to dig it up on a Landcruiser forum (I think that's where I had found it). There are a few seals (orings) in there. Good Luck.