At my wits end bleeding these brakes...

[turbocharged]

So, let me start by saying I have bled the brakes on tons of car and have never experienced anything like this before. This is on a '99 4WD Limited

It began as a simple upgrade/replacement....front brakes to Tundra 13WL calipers/rotors/pads and replaced rear shoes and drums. When I got in the rear brakes I noticed one of the wheel cylinders boots had a pin size hole in it, so I replaced both wheel cylinders as well. Reconnected everything and began flushing/bleeding.

Using the 2-man method, could not get it feeling good, so we bled the master cylinder. Still no dice. Bought a new master cylinder, bench bled that, and hooked up the new Motive Power Bleeder to save my brother-in-law's leg. Still nothing.

So right now here is what I have...
- New 13WL Tundra front brake calipers
- New rear wheel cylinders
- New master cylinder
- Zero air bubbles coming out of any bleed screw
- Very firm pedal with engine off
- Mushy pedal that falls to the floor with engine on

I can't find any leaks anywhere and every place I can bleed has been bled. Only other thing I can think of is air trapped in the ABS unit, but everything I have read says that it is completely passive until engaged.

Seriously...any help is appreciated as I really need to drive this car on a trip tomorrow and have been working on it all week.

 

[LittleCaesar]

I have to ask what brand of rear wheel cylinders you bought. Years ago I bought some Dormans I think to replace the Aisin ones. Bad idea, I just couldn't get them to work and had a semi soft pedal. Got a rebuild kit from the dealer for the OEM ones and were fine afterwards.

Tried bleeding KOEO? This works and is mandatory for the rears for 01-02 models but is worth a shot.

Pull the ABS fuse, then try to bleed them again as a last resort. If the brake fluid was quite old beforehand, it is possible your ABS modulator went south.

 

[Juppers]

Did you adjust the drums? If there is too much play there that could cause some issues.

 

[turbocharged]

Wheel cylinders are Carquest Wearever. I may replace them with Napa parts just to try something else.

I'm assuming KEOE is Key On, Engine On....and no I did not try that. I did bleed key On only though. Didn't think engine on was necessary on the 96-00 4Runners. Is this not the case?

I wouldn't doubt my ABS is dead because it never tries to activate as it was. Would pulling the fuse do anything though? It was my understanding that the ABS unit did nothing untIL a lock up.

 

[turbocharged]

Did you adjust the drums? If there is too much play there that could cause some issues.

Yes, drums are adjusted until a slight rub can be heard but no resistance felt.

 

[TheHoneyBadger]

Wheel cylinders are Carquest Wearever. I may replace them with Napa parts just to try something else.

I'm assuming KEOE is Key On, Engine On....and no I did not try that. I did bleed key On only though. Didn't think engine on was necessary on the 96-00 4Runners. Is this not the case?

I wouldn't doubt my ABS is dead because it never tries to activate as it was. Would pulling the fuse do anything though? It was my understanding that the ABS unit did nothing untIL a lock up.

When i did the TBU i had to bleed with the engine running to get a good pedal.


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[stir_fry_boy]

When i did the TBU i had to bleed with the engine running to get a good pedal.


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This ^^^

Or gravity bleed them. That's what I do. Start with the passenger rear --> then driver rear --> passenger front --> driver front.

 

[turbocharged]

stir_fry_boy, I see you have a 2002 4Runner which has a different brake system than the 96-00 models. I believe the bleeding procedure is different as well. Not sure if this matters though.

TheHoneyBadger, what year is your car?

Also, when you guys bled with engine on did you bleed two man method or with power bleeder?

 

[4Reak Show]

Does your rig have the integral ABS/master cylinder combo? On these the abs motor is what assists the master to help you push the pedal. I learned thru work recently that bleeding these style systems is best KEY OFF and bypassss the whole abs motor business.

If it's a standard stand-alone master cylinder, that should be straight forward. There's also the soda bottle method to try: old soda bottle, fill with 1-2" of new brake fluid, run a hose SUBMERGED into the fluid and then to the bleeder port. Crack the bleeder and pump 5-10 times per wheel and refill master. (This way when the pedal travels upward is pulls in new fluid)

Also I assume you're bench bleeding the master as well as cracking the hose connections with pedal pressed after install? It's a forgotten step sometime as air gets trapped right at the hard line connections.

Good luck

 

[turbocharged]

Does your rig have the integral ABS/master cylinder combo? On these the abs motor is what assists the master to help you push the pedal. I learned thru work recently that bleeding these style systems is best KEY OFF and bypassss the whole abs motor business.

If it's a standard stand-alone master cylinder, that should be straight forward. There's also the soda bottle method to try: old soda bottle, fill with 1-2" of new brake fluid, run a hose SUBMERGED into the fluid and then to the bleeder port. Crack the bleeder and pump 5-10 times per wheel and refill master. (This way when the pedal travels upward is pulls in new fluid)

Also I assume you're bench bleeding the master as well as cracking the hose connections with pedal pressed after install? It's a forgotten step sometime as air gets trapped right at the hard line connections.

Good luck

It is a stand alone MC. Two ports on the LH side, then ABS unit on RH wheel well. That is why I'm so confused.

I also did crack the lines from the MC after the bench bleed. I'm now considering cracking the fittings on the ABS unit with the power bleeder hooked up and seeing what happens.

 

[4Reak Show]

Interesting. I have had bad components out of the box before so it is possible the MC is just no good. The other option since you're saying it gets worse when engine is running is the vacuum booster. Although is it suspicious if it all worked well prior to brake upgrade. It's gotta something simple we're overlooking. What about a vacuum bleeder type deal on the front to ensure totally bled?

Also, don't be you're own worst enemy...too many times I get into my own head and create problems that actually don't exist out of paranoia.

 

[gamefreakgc]

Wheel cylinders are Carquest Wearever. I may replace them with Napa parts just to try something else.

I'm assuming KEOE is Key On, Engine On....and no I did not try that. I did bleed key On only though. Didn't think engine on was necessary on the 96-00 4Runners. Is this not the case?

I wouldn't doubt my ABS is dead because it never tries to activate as it was. Would pulling the fuse do anything though? It was my understanding that the ABS unit did nothing untIL a lock up.

Also had to bleed with engine on. You can speed bleed each tire in 10 seconds if you just have them keep constant pressure on the pedal, the brake booster does the rest! Just open the bleeder and the fluid shoots out.

 

[mckennar]

This is going to sound stupid, but it worked for me... I had soft pedal and a lot of travel after the TBU and bled what felt like gallons of brake fluid through the system without successfully hardening up the pedal or doing much in the way of lessening the pedal travel.

One day on the way home from work I had a panic stop (car in front of me rear ended a stopped car on the highway) and the ABS actuated (barely).

After that my pedal travel was *worse* than before and it was still just as soft. So I bled the system again and got a few bubbles out of the passenger side rear. I bled the rest of the system without any more bubbles.

After the second bleeding post-ABS actuation, the pedal feels just as hard as my wife's brand new 2016 4Runner Trail with much less travel.

My theory is that there might have been some trapped air in the ABS unit?

But please don't take my word for it on this one, this is pure anecdote.

EDIT: I also had to reverse while yanking the e-brake a few times to restore pedal travel after each of these bleeds.

 

[MStudt]

I feel your pain since I just went through this. I bled them with the vehicle off first. Then with the vehicle on, and then off again. After that they started feeling pretty good.This was on an 01, but the same bleeding process can be followed. I also did NOT bleed the rear drums.

 

[TheHoneyBadger]

stir_fry_boy, I see you have a 2002 4Runner which has a different brake system than the 96-00 models. I believe the bleeding procedure is different as well. Not sure if this matters though.

TheHoneyBadger, what year is your car?

Also, when you guys bled with engine on did you bleed two man method or with power bleeder?

I have a 99. I used the two man method.

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[absalom]

I wrote a TBU brake bleeding tutorial after finally solving my own issue after months of spongy brakes, but I can't seem to locate it.

The short and curly of it was, panic stop on gravel a few times, head home. Then, have your partner pump 5x suuuuper slow and hold, and proceed to crack the lines like normal. What I found was that by pumping quickly, or even at a normal speed, the master cylinder was creating aeration. I'm guessing it was where the plunger lip seats against the MC barrel, but who knows.

These trucks are known to occasionally trap bubbles in the ABS solenoid, so the panic stops prior to bleeding will flush fluid through them. But in the end, sloooowly pumping the brakes was the key. I ended up with rock hard brakes, perfect modulation, and greatly increased performance.

Also, don't forget to properly bed your brakes after installation as well. This, in of itself, can have a big effect on pedal feel in the end result.

 

[IBallEngineer]

It began as a simple upgrade/replacement....front brakes to Tundra 13WL calipers/rotors/pads and replaced rear shoes and drums. When I got in the rear brakes I noticed one of the wheel cylinders boots had a pin size hole in it, so I replaced both wheel cylinders as well. Reconnected everything and began flushing/bleeding.



So right now here is what I have...
- New 13WL Tundra front brake calipers
- New rear wheel cylinders
- New master cylinder
- Zero air bubbles coming out of any bleed screw
- Very firm pedal with engine off
- Mushy pedal that falls to the floor with engine on

So I'm curious if you ever solved this. I know this is unlikely but I once had a funny issue on a CJ5 that I bought a complete front axle for. I installed it, in my shop and since I was super busy I asked one of my guys to take care of bleeding the brakes. The brakes ended up spongy and when I drove it I decided to bleed again. I was up top pumping and my employee was bleeding. It did not improve so I set the jeep aside for a few days. Well after a few days I looked at it and noticed the master was leaking a little on to the firewall. Being I was so busy with shop work(body shop) I sent the jeep down the street to a friend to install the master. It got better, but I was just never happy with it. One day I drove it to another shop and I mentioned to the owner the whole story. He got down on one knee and looked at the calipers. He stood up and told me I was setting him up. The calipers were installed on the wrong sides, so the bleeder was on bottom instead of the top. Swapped sides and the Jeep brakes worked great!

:lookout:

 

[TheDurk]

So I'm curious if you ever solved this. I know this is unlikely but I once had a funny issue on a CJ5 that I bought a complete front axle for. I installed it, in my shop and since I was super busy I asked one of my guys to take care of bleeding the brakes. The brakes ended up spongy and when I drove it I decided to bleed again. I was up top pumping and my employee was bleeding. It did not improve so I set the jeep aside for a few days. Well after a few days I looked at it and noticed the master was leaking a little on to the firewall. Being I was so busy with shop work(body shop) I sent the jeep down the street to a friend to install the master. It got better, but I was just never happy with it. One day I drove it to another shop and I mentioned to the owner the whole story. He got down on one knee and looked at the calipers. He stood up and told me I was setting him up. The calipers were installed on the wrong sides, so the bleeder was on bottom instead of the top. Swapped sides and the Jeep brakes worked great!

:lookout:

I don't think there is any way to connect the lines to an upside down caliper on our trucks. There is a hardline to a bracket on the knuckle--then the softline. You would have to be very persistent to screw up that way and make major changes to the lines.

Good story, though.

 

[squarejer]

Did you ever fix this problem, turbocharged? I have same issue

So turbocharged, did you ever fix this problem?

I have the same issue and am stumped. Soft brakes with lots of pedal travel.

98 4Runner
Swapped in 3 new master cylinders (bench bled each time)
replaced both rear cylinders
Bled brakes six times, 3 of those times after activating ABS
replaced both front brake hoses
Inspected front brake calipers and confirmed no leaking pistons

The one thing I have not yet done is a scan tool bleed. I am out of ideas otherwise.

Anyone have any other suggestions?

 

[squarejer]

ABS Unit was bad

I guess this is an orphaned or abandoned thread. I got no replies.

Nevertheless, I'll do what most other people seem to not do.... come back and explain what actually fixed teh problem.

I took my 4Runner to Toyota. They replaced the master cylinder (making it the fifth master cylinder on this truck), but that did not fix the problem.

Then they replaced both front brake calipers with new calipers, but that did not fix the problem.

They were very certain the rear brake hose and both proportioning valves were good, so that left only one thing: the ABS unit.

They found a used unit, installed it. And now the brakes are as good as new!

There was NO ABS error light or error code. One of the internal solenoids must have failed to close off one of the internal pathways.