Brake Master Reservoir blowing fluid out reservoir cap???

[2001LC]

I've looking at a 01LX brake light came on. First check was fluid level. It was low. But strangely low on DS compartment. Compart in front is overfilled. As I pump pedal 40 times key off. Fluid come out the cap. It a good cap good seal.

Anyone seen this before or a thread anywhere on this?
Any clues, ideas on what cause?

 

[FxFormat]

Weird, im looking at a 100 series and i'm seeing the same thing in the reservoir, how weird, never seen this before either. Service history shows dealer scanned an ABS code. C1223

 

[2001LC]

Is the one you're looking at, blow fluid also?

I've spoken with some other mud guys around the country this morning. They've not seen either. I feel too risky, to not replace master at this point. I know for sure, any and all Toyota & Lexus Dealership would recommend R&R.

But I'd sure would like to know what's going on.

 

[2001LC]

Nobody around or we're only two to see this

 

[badlander]

Sorry I can't offer any help with your issue but out of curiosity, do you have any ideas or knowledge regarding the design of the separate fluid compartments in the reservoir and the dedication of each one?

 

[2001LC]

Sorry I can't offer any help with your issue but out of curiosity, do you have any ideas or knowledge regarding the design of the separate fluid compartments in the reservoir and the dedication of each one?

No! I may cut one open.

I'm considering swapping this reaservoir out for another I have. To see if any difference. I suppose it could possible be a chamber inside has failed.

But I suspect it's issue is a valve or seal within master/ABS unit has failed. It has brakes, so seem pressure is being delivered to calipers.

The fluid coming out reservoir, was while I pumped brake pedal 40 times key off. But just normal brake use fluid blew out cap also.

In any case, system alerted driver with brake light. Brake light coming on with E-brake off. Indicates low fluid, which I had warned owner to watch for and stop driving until reason found anytime light comes on..

 

[hoser]

The reservoir is difficult to clean. I suspect there is an internal filter/screen but haven't confirmed. In your case, possibly clogged.

 

[2001LC]

Hummmm. Could be, I'll pull reservoir and see what I can find out.

I can say, fluid been flushed twice over last 5 yrs/100K miles twice. But unknown if flushed first 15 years 200K miles. Reservoir only mildly staining, so likely was flushed once or twice in earlier years/miles. Flushing is key to keeping it clean.

 

[2001LC]

I've been searching online.
I see suggest but no actual confirmation of cause or fix:
1) Air in system. Response: bleed multiple times, no air.
2) Obstruction in reservoir. No confirmation or fix.
3) Portion valve. No confirmation or fix.
All were just guessing, it seems!
Note: No Land Cruiser found in search. Toyota along with some USA made vehicles, reporting the same symptoms. So far, all I found, each thread ended without resolution.

Once I get some time: I'll hook to tech stream. See if any pending codes or freeze frame data can help understand what happened and when. Run through some active test. But other than brake light on indicating low fluid, no other dash warning lights. I'll also add fluid and take on dirt road, to activate ABS. Which will also slush around fluid in reservoir. If a clogged in res, it may dislodge.

I may speak with a good Master Diagnostic Technicians at Toyota. But I know what his response will be. "Replace the master." Dealerships I know, will not touch these master, except to replace it or add fluid period! Most do not even know Toyota sell a master plugger kit.

Whereas this could possible be a blockage in reservoir. That implies very old fluid buildup solids. Then clogged it. I'm 98% sure that did not happen in this case. Fluid is medium dark now, but not more than normal for age and miles since last flush I did 3 yrs / 60K ago. Staining is also minimal. History shows 2014 flush before that. Although at the time (3yrs ago) I was not using Toyota brake fluid exclusively, and reasonably sure other did not either. Which today Toyota is only fluid I use. Reason; extra insurance against seal damage. Unless owner or someone put something in reservoir (2% chance), which is not likely. I fear this is inside master, very possible deep in back cylinder (near front of vehicle) where we can't get to. I suppose it could be ABS unit, but happens key off. So not likely, unless valve stuck in ABS controller.

I may replace reservoir before pulling master, to see what happens. I'll pull master plugger once on the bench. See if anything seems out of the norm. All time permitting.

But unless I can pinpoint outside of master, ABS or plunger (seal) in master. I must replace the whole master assemble. Risk is just to high otherwise.

Note on Brake fluid:
I was using most any top shelve DOT III brake fluid, until last year. Before that I gave people option of fluid brand. But after seeing the number of failed master in Toyota & Lexus at a Dealership, that just one mechanic replaced in just one week (about half a dozen, not one a 100 series). I then found out Toyota shps use bulk brake fluid (not Toyota fluid as is to expensive). Then recalling a TBS and Recall of 05-07 Toyota and Lexus (not 100 series), for brake master seals damaged. Damaged was sighted in TSB as caused by off the shelve non Toyota brake fluid, being added to reservoir.So I began using Toyota fluid only.

Could it be the Toyota brake fluid is designed for our seals (brake rubber) with seal modifiers. That use of any other, may be damaging our seals. That is what the TBS implied. Then seal debris is blocking a valve...Hummmmm

 

[2001LC]

Spoke with Master at Toyota Dealership. He's not seen this. Asked if he did, what they'd do to repair. Stated: "Replace master". No surprise!

Also no surprise. Wholesale parts dep., is seen big increase in brake master purchases across all models.

Could in be, the off the shelf DOT 3 & 4 brake fluid again damaging seals If yes, than a recall should be paid for by Toyota again. As any OM I've read, states: "or equivalent DOT".

 

[2001LC]

One thought was accumulator reputered. I can NOT see how that is the case!
I say NOT! Because the system takes 30 pumps on pedal to discharge accumulator and charges in 35 sec. Which is only 2 pumps & 1 sec more than when tested 4 months ago. (Note: charge time will vary based on battery volts). I cannot see how it would even charge at all if ruptured, or at least one would think it take a very long time to do so. Seem booster motor would just keep running or at least for a very long time. But a ruptured accumulator would explain contaminate in reservoir.


Here's a picture from flush in 2018. Note reservoir does not look stained or dirty. At that time I used non Toyota Brake Fluid. History showed it had been flushed prior to 2018, which it's very likely non Toyota brake fluid used in all flushes.

In April 2021 I topped reservoir with 1/2 can (~6oz) Toyota brake fluid.

Now prior to removing master, reservoir is stained. The small upper chamber (front center top) is very dark

As I further inspect just after removing master, while dumping fluid out. I noted a lot of contaminants/particles just under cap area.

So where did the contaminate come from???

 

[Tmparker05]

was there any resolution to this? I’m seeing fluid coming from the cap in mine which I followed from a line below the vehicle. Fluid is at the correct level and isn’t throwing any codes.

 

[2001LC]

It's believed. Seals in the master are failing, allowing excesses backflow into reservoir. This is somewhat supported by the bits of debris seen. Debris is sign of improper fluid service, which damages seals. These seals are not sold by Toyota, nor has anyone to my knowledge sourced or replaced them.