2003 T4R , brake master cylinder, ABS unit kaputt
 

My T4R was driving nicely over teh years but last week I saw the brake warning light on the dash. I had never seen this during driving (I think it lights up when the foot brake is engaged).
It must have been signaling low brake fluid. I never had this before on this car.
I was driving another few miles, I was wondering why the brake pump motor was making abnormal sounds, then parked the car.
After the stop I wanted to drive back home... but after 1/4 mile the dash started blinking (ABS, VSC/Trac and making an awful sound). Brakes did not work after that. I had the car towed home.
I noticed at home that there was no brake fluid in the reservoir.
Where would this fluid go all of a sudden?

Anyhow I ordered a reman motor/accumulator unit and want to install it.
Questions:
- Can I R&R the motor/accumulator unit directly without removing the entire hydroboost?
-Or do I need to remove the entire unit and then change the motor/accumulator, then put it back in?
- Any codes to cancel after the job?
- I will check all the brakes calipers again even though 2 years ago I was rebuilding all brake calipers due to dragging /seized pistons and do proper bleeding.
(I don't know what Toyota was designing with these brakes, pistons are every prone to seizing).

Any help is very much appreciated.
Martin

With you being in the snow/rust belt, it sounds like a busted/rusted out brake line to me.

Did you look for where the brake fluid leaked out?

If you do have a busted/rusted out brake line it would do exactly what you have describe, the booster pump would run continuously and no brake pedal, this is especially true for a busted brake line going to the rear.

I would check all along the metal brake lines for the leak before I would do anything to the brake/ master cylinder/ABS pump/booster!!

Totally agree with AuSeeker.

yes, check the lines first. had one bust a little while ago, very easy for fluid to leak out quickly in that scenario.

Thanks Auseeker and others,
You were right. I see a mayor leak in one of the 2 rear lines close to the rear axle, shortly before the line switches to a flex hose toward the rear brake.
It is one line to the RR brake. There are two lines, one for LR and RR that starts behind the left frame member before the tank and then disappear behind the tank and tank protection. Thank protective shield is rusty as hell and it would be a pain to remove for sure. But there is probably no other way in order to remove that old RR line.

You are absolutely right about the rust underneath and the rusted out brake line. It is a shame to see so much rust under the car that makes every move more painful than it should, down there. Every old bolt will simply be seized and snap, typically... then I need to weld (weld against what...if there is rust only) and get another thread fixed somehow for a new bolt.

At least I was lucky and I could remove the union screw (M10 x 1) from the connector fitting that translates to the flex brake hose. In the picture you see that I cut the end of the line already.

Two ways to fix this line:
1) Try and get a new line from Toyota ( Any information about the line part number number I need?). Changing that line could be a pain depending on how to get the old line out. If there are difficult line brackets to the frame (That is what I think), behind the tank, boy that could become a project.
2) Cut the end piece of the rusted out line and extend the last 2" by adding a piece of new line ( flanging etc involved... maybe also not easy down there to do the cutting and flanging).


let me know if you would do option 1 or 2.

So yes I found the leak... very happy about this. That explains the initial brake warning light that turned very fast into the full christmas tree blinking.
I understand that the hydroboost will act up if there is no fluid left for the electric pump to pressurize the accumulator... And no pressure in the accumulator meaning: the christmas tree is lit in the dash along with the christmas trompet.

Is it true that the accumulator pressure will activate the dash lights? If the pressure is too low the dash starts acting up?

Well before I drove the car into the garage yesterday I filled the brake fluid reservoir , started the engine but I did not hear the booster motor runnning as it should.
There could have been simply no pressure building up with the leak and therefore the motor does no sound?
Or it did run and I did not notice because it was running with no load on the pump... fairly silent?
What Pump is Toyota using for the booster? Is this a simple gear pump?

I am trying to go step by step.
First to get the leak fixed and then test if the booster motor works (maybe do some bleeding first in order to remove a good portion of the air?)

Thanks, Martin

you can probably use this to find the part number, its a Canadian site but at least you can use to get the part number

2003 Toyota 4Runner SR-5 4700CC 32-VALVE DOHC EFI, AUTOMATIC 5-SPEED SR-5 4700CC 32-VALVE DOHC EFI, AUTOMATIC 5-SPEED Brake Parts | Toyota Parts Direct

Thanks rumfoord,

I ordered both of these lines, one of which is broken but I fear the other line may be not far behind (rust).

I saw in the diagram that the lines snap into plastic clips along the frame... so I hope to get them out and the new line back in without bigger complications.

Part numbers I ordered: the 2 brake lines along the left frame -between frame and tank- are 47324 35310 (feeding right side rear brake) and 47325 35390 (feeding left side rear brake)


For replacing the brake booster motor/pump/accumulator I am planning to disconnect the entire hydraboost unit. (should be straight forward... outisde: remove the 4 attached brake feed lines and cable plugs. inside: disconnect the piston pin at the brake pedal, remove the 4 nuts)

Thanks for the help.
Martin

why do you think the brake assy/pump is still bad?..i though you have seen the culprit?--being the leaking brake lines?

2ndly, yes, i have changed only the pump assy in-siyu without removing the whole assembly, its difficult, not impossible

I agree with the others - I would replace the lines first (and any other source of leaks). After bleeding the system completely/no air, then check to see if all is working. I wouldn't commit to replacing the pump/motor/accumulator just yet.

Being in the Northeast I'm surprised your brake lines lasted this long. I replaced them all a few years ago on my 03 because they were all junk or going to be soon. I went with a roll of copper nickel line and new ends flaring the lines myself. This type of line is easy to bend and does not rust. As for the line up over the tank, I ripped out what I could and just threaded the new line up over it as best I could. Having a straight brake line with no bends made it easier. My tank protector was already cracker material so I just ripped that off.

Thanks earthrealm,

Some weeks before this incident happened (massive fluid leak) I noticed that the brakes are a bit wierd. Brake power was not as before and I heard the motor of the booster more often. But there was no dash light at all, meaning there was no fluid loss.
I was suspicious that probably one of the front brake calipers seized (I had this before). However I rebuild all calipers only 2 years ago. I had to replace one of them because the piston was seized so badly.

Then the story with the sudden brake fluid leak started.

After I fixed the rear brake line I am assuming I have no more leak.
And I could simply bleed the brakes and see if everything is working.
However the hydroboost unit is most possibly original and after 210K it is probably time to replace that motor and accumulator while I am there?

Martin

Hi Rocket,
I see what you guys are saying.
I might simply do what you suggest and see how it goes.

After bleeding the system do I need to reset any codes via OBD2.

Worst case I need to empty the system again and work on the hydroboost

Martin

Hi Mike in NH....
Great to have someone close by with a rusty T4R.
Underneath this car looks really ugly. Every bolt you need to remove is rusted out and snaps (haha, whom am I telling that).
I was welding quite a bit down there, frame rear axle end stops and rear end.
(I have a couple of old Mercedes cars 1970, 1984, 1992) and none of these cars has these rust problems...I can remove any bolt. I assume this is a Toyota disease.

Brakes: Your idea with cunifer lines is great. If I am keeping the car I'll do the same- replacing all the lines.

Martin

I wouldn't touch the booster yet either, pricey bugger that some never need to touch. No need to clear any codes that I can recall. There's a process for it listed in a sticky here. Don't be surprised if it beeps at you during the bleeding process.

Ugh, I never realized how bad it was until we got a used Southern rear frame section for my son's Ranger. It looked better than some cars here that are 2 years old. No not really a Toyota disease but possibly not on some quality older cars. Fords, Chevys, Hondas, Nissans, Jeeps and of course Toyota, these are all cars I've had to weld new metal into the past 15 years. My son's F150 needs another frame hole repaired, that's number 3 for him I think. Inspection time for me so I went over my 4runner only to find 5 new holes in the frame that need steel welded in. Ugh. If I could buy a decent one for under 15k that is late in the Gen4 cycle I think I would.

Hi

I managed to install a new Toyota brake line.... It was painful to install.
Needed to get the tank lowered for at least some access to that stupid line.

Well I have the new line installed (took me a couple of weeks) and I did the bleeding today. It holds fluid and pressure now and the system should be fully bled, but for some reason the alarm sound and dash lights is still continuing.

What does this mean?

A) Do I need to clear a code in order to cancel the alarm?
B) Did I do something wrong (bleeding?) or did I forget something?
C) Is there more work to do (as I suspected the brake booster pump/motor)?

I simply don't know what the alarm coning means.

In case the booster motor is failing... would it give the same alarm?

Martin