Brake Gremlin

[werminghausen]

So mine is pretty similar to Sam's except the motor runs at 2 or 3 pumps of the brakes. Then the 3-5 seconds pump on to keep pressurized. The alarm never goes off no matter how much I pump it but it has in the past. It went off when I blew a brake line and when I had a brake pad seize in the caliper. For the latter, it would only go off if pumped a bunch and I had a super squishy pedal as the pad was pushing the cylinders back in when I let go of the pedal.

One thing about my 220k+ unit is that it is super quiet. I have to listen hard to hear it and local traffic noise would make me miss the sound.

Thanks Mike,
Your motor comes on every 2-3 times you hit the brake. That is quite a difference to Sam's 5-10 times.
You also cannot trigger the alarm but you mentioned that you could trigger the alarm in the past when you had a problem with a seized brake pad that worked like a big spring pushing the brake piston way back... that would be like if you had a lot of air in the system... meaning the master brake cylinder has to pump much more fluid each time you hit the brake.
Interesting and I fear I am having some similar issue with my brake calipers/pads.

I am assuming your brake calipers /brake pads are fine now? and still you have the brake motor much earlier (2-3 times) than Sam (5-10 times).
How squishy is your brake now?

Martin

 

[SocalSam]

Now that I am hyper-sensitive to my brakes, I counted the number of stops before the pump came on. It was a lot closer to 5 than 10. Pump came on for a couple of seconds. I'm still satisfied with brake operation. I was just kidding about being hyper-sensitive, lol.

 

[MikeinNH67]

I am assuming your brake calipers /brake pads are fine now? and still you have the brake motor much earlier (2-3 times) than Sam (5-10 times).
How squishy is your brake now?

Martin

Brakes are fine now, yes to both. Only a bit of squish but close to the best they've ever been but certainly not as good as my much newer Sienna. Those brakes are amazing.

 

[werminghausen]

update hydro booster:

I installed the new hydro booster, I did no other changes.

The good news:
The brake alarm does not show after I was driving for 2 days. But I am still alert.

The bad news:
The brakes perform just the same as before: Soft and squishy. The brake pedal needs to be pressed too far in order to stop the car.
And the brake motor also comes just the same as before: After every second brake action... that motor runs.


My understanding.... The new hydro booster takes the most annoying brake alarm away (so far!) but it does not improve the braking performance.

Result: The old master cylinder is good. And what triggered the alarm (if the alarm continues to be silent) must then be a problem in the ABS /TRC block next to the master cylinder.
It also means that the squishy brakes are caused by something else in the system (could be calipers or still air in the system)

Where to go from here? What are your thoughts?

Anyone interested in the old hydro booster?

 

[SocalSam]

update hydro booster:

I installed the new hydro booster, I did no other changes.

The good news:
The brake alarm does not show after I was driving for 2 days. But I am still alert.

The bad news:
The brakes perform just the same as before: Soft and squishy. The brake pedal needs to be pressed too far in order to stop the car.
And the brake motor also comes just the same as before: After every second brake action... that motor runs.


My understanding.... The new hydro booster takes the most annoying brake alarm away (so far!) but it does not improve the braking performance.

Result: The old master cylinder is good. And what triggered the alarm (if the alarm continues to be silent) must then be a problem in the ABS /TRC block next to the master cylinder.
It also means that the squishy brakes are caused by something else in the system (could be calipers or still air in the system)

Where to go from here? What are your thoughts?

Anyone interested in the old hydro booster?

I wish you could try my brakes and compare to yours.

I'd love to get my hands on a spare mc/abs valve block. I would do a tear down and post photos. Would it fit in a USPS medium flat rate box 11.25 x 8.75 x 6 inches?

 

[AuSeeker]

[MENTION=114238]werminghausen[/MENTION]

Martin,

Did you somehow bleed the ABS system?

If not that could be some of the issue with pedal feel.

Well I'm going to attempt to change out my assembly tomorrow, the electric motor no longer does anything now, constance alarm now, do have any advice or have any difficulties when R&R yours?

 

[SocalSam]

Removal and install are straight forward.

 

[AuSeeker]

I just finished installing the ABS/master cylinder assembly, so far so good, I only bled the master cylinder at this point and the brakes are pretty good.

It took several minutes to get the alarm to stop, the electric motor on my assembly seems to only run for about 5 seconds then stops for about 5 seconds and then runs again for 5 seconds, this continued for at least 10 cycles before the alarm stopped, I then depressed the pedal about 7 to 8 times and the alarm returned...but only for about 5 to 10 seconds, after that I couldn't get the alarm to trigger even after over 20 depressions of the pedal, I'll report back later as to how many depressions it takes to get the motor to trigger again.

I will at a later date do a full 4 wheel bled and also use my new scanner to bleed the ABS system and post if any improvement over how the brakes work now.

As mentioned it was straightforward to do the R&R....but I would say it was far from easy getting to the 4 nuts under the dash and I have cuts and scrapes to prove it!!

I did have to remove the screws/bolts/nuts for the fuse block and a couple of brackets to gain better access to the master cylinder nuts, I only lost one nut that fell down between the seat and console apparently never to be seen again, I spend close to an hour trying to find it using a magnet and my arms, but no luck, I did however find all the other numerous items I have dropped down there over the last few years!!

 

[SocalSam]

I just finished installing the ABS/master cylinder assembly, so far so good, I only bled the master cylinder at this point and the brakes are pretty good.

It took several minutes to get the alarm to stop, the electric motor on my assembly seems to only run for about 5 seconds then stops for about 5 seconds and then runs again for 5 seconds, this continued for at least 10 cycles before the alarm stopped, I then depressed the pedal about 7 to 8 times and the alarm returned...but only for about 5 to 10 seconds, after that I couldn't get the alarm to trigger even after over 20 depressions of the pedal, I'll report back later as to how many depressions it takes to get the motor to trigger again.

I will at a later date do a full 4 wheel bled and also use my new scanner to bleed the ABS system and post if any improvement over how the brakes work now.

As mentioned it was straightforward to do the R&R....but I would say it was far from easy getting to the 4 nuts under the dash and I have cuts and scrapes to prove it!!

I did have to remove the screws/bolts/nuts for the fuse block and a couple of brackets to gain better access to the master cylinder nuts, I only lost one nut that fell down between the seat and console apparently never to be seen again, I spend close to an hour trying to find it using a magnet and my arms, but no luck, I did however find all the other numerous items I have dropped down there over the last few years!!

My re-install was good from the start. No excessive pump run, no alarms, normal braking. I only replaced pump and accumulator so my valve block was wet. I think a new unit is bone dry so it takes some pumping and solenoid action to circulate fluid throughout.

I dropped a nut in some inaccessible spot but got lucky and was able to fish it out with a magnet. Finding right combination of wobblies and extensions for the nuts was easily the hardest part.

 

[SocalSam]

On a side note, I now have a full set of brake relays. I also snagged the purple A/C relay. Colorful buggers. The donor 2003 was missing ABS/MC assembly. That unit is usually the first to be picked. I wanted to pump the brakes to compare to mine.

 

[werminghausen]

I just finished installing the ABS/master cylinder assembly, so far so good, I only bled the master cylinder at this point and the brakes are pretty good.

It took several minutes to get the alarm to stop, the electric motor on my assembly seems to only run for about 5 seconds then stops for about 5 seconds and then runs again for 5 seconds, this continued for at least 10 cycles before the alarm stopped, I then depressed the pedal about 7 to 8 times and the alarm returned...but only for about 5 to 10 seconds, after that I couldn't get the alarm to trigger even after over 20 depressions of the pedal, I'll report back later as to how many depressions it takes to get the motor to trigger again.

I will at a later date do a full 4 wheel bled and also use my new scanner to bleed the ABS system and post if any improvement over how the brakes work now.

As mentioned it was straightforward to do the R&R....but I would say it was far from easy getting to the 4 nuts under the dash and I have cuts and scrapes to prove it!!

I did have to remove the screws/bolts/nuts for the fuse block and a couple of brackets to gain better access to the master cylinder nuts, I only lost one nut that fell down between the seat and console apparently never to be seen again, I spend close to an hour trying to find it using a magnet and my arms, but no luck, I did however find all the other numerous items I have dropped down there over the last few years!!

Congrats Au,
I had the same experience removal and installation when I did it the first time. Second and third time you already know... much faster.
Best to have the most flexible extrension for these 4 buggers and a good head lamp.
The running of the motor for the new unit was the same in my case.

I did perform the master cylinder bleeding but did not do the calipers. I did the calipers extensively with no positive outcome for the softness of the brake.

I have the car on the lift now and want to go through all calipers, see if I can see any problems during resealing. I will check if some are stuck or any other issues with them. if I don't find any obvious problem with these calipers I am at a loss what can cause this bad brake performance with a brand new hydro booster unit.
(remember I had squishy brakes weeks before I had the brake incident with the alarm. So I am not surprised that this issue did not go away if it was caused by something else than the hydro booster)

Au, can you report from your bleeding experience with the new scan tool you bought? Did I understand correctly that the scanner is doing all the tricks to bleed brakes without removing the air through cracked lines like during manual bleeding? How the heck does this work? Where is the air going?

Martin

 

[AuSeeker]

Congrats Au,
I had the same experience removal and installation when I did it the first time. Second and third time you already know... much faster.
Best to have the most flexible extrension for these 4 buggers and a good head lamp.
The running of the motor for the new unit was the same in my case.

I did perform the master cylinder bleeding but did not do the calipers. I did the calipers extensively with no positive outcome for the softness of the brake.

I have the car on the lift now and want to go through all calipers, see if I can see any problems during resealing. I will check if some are stuck or any other issues with them. if I don't find any obvious problem with these calipers I am at a loss what can cause this bad brake performance with a brand new hydro booster unit.
(remember I had squishy brakes weeks before I had the brake incident with the alarm. So I am not surprised that this issue did not go away if it was caused by something else than the hydro booster)

Au, can you report from your bleeding experience with the new scan tool you bought? Did I understand correctly that the scanner is doing all the tricks to bleed brakes without removing the air through cracked lines like during manual bleeding? How the heck does this work? Where is the air going?

Martin

Martin,

No the scanner doesn't bleed the brakes for you, you do have to open the bleeder valves, the scanner is for only bleeding the ABS system by triggering the ABS valves to open to get air out of the valve body and then you do the regular bleeding again to remove the air, the only other way that it is said to get the air out of the ABS system is to do several hard braking sequences on a dirt road, snow or wet road to get the wheels to lock up and trigger the ABS system to activate and thus push the air from the valve body, I don't know if that truly works or not but several members here have reported it worked for them, either way you still have to manually bleed the lines again after to remove any air that may have been in the ABS system, I would think just bleeding the master cylinder again would remove this air, so that how I would proceed, do the ABS bleed, master cylinder bleed and then finally the 4 wheels.

That being said as I mentioned I haven't bled the ABS system yet using the scanner or otherwise, all I did was bleed the master cylinder by loosening the 4 brake lines at the master cylinder while my son worked the brake pedal.

The brake pedal seems to have to travel a tiny bit further than it did before the R&R before any braking action becomes apparent...but when the braking action starts it's much much better than it was before the R&R and the pedal is firm at that point.

 

[werminghausen]

Thanks Au,
that makes sense... the air come out the traditional way.
it is hard to trigger the ABS on the lift -I guess- without that magic tool.
So there is another step involved without that tool.

Martin

 

[werminghausen]

Update after removal of Right Front caliper.
During removal I already saw the mess on the backside of the disk.
It turned out that one inner side piston was entorely stuck which forced the second piston to compensate.... but this is a mess as we know. One piston did not move any more and the second tries to do the job but of course it has only 1/2 the force of the okay outer side. It is entirely asymmetric to a point when the steel disk is bending in theory... I guess there could be a bigger 'Spring effect' until the brake really bites.... This does the following
A) reduces braking force
B) I might lead to a much bigger fluyid volume to pump until the brake does anything
C) The large amount of fluid moved means that the accumulator is emptied much faster than it should.

I am simply trying to understand my symptoms better...why they occur (remember brake motor running every second time and bad brake performance).
I was guessing this might be my problem for a long time but did not follow up until now.

The stuck piston: I drilled a hole into the housing opposite of the stuck piston and hammered it out with a punch.
You also see that the outer edge of 3 out of 4 pistons has corrosion.
How could that be as this is a rebuilt calipe I bought from Napa 3 years ago, maybe 3.5 years?
The paint or powder of the caliper is entirly failing... My guess is that the flaking off powder at the seals let water and moisture inside and thus the pistons were starting to corrode.
It would be so much better if they did a proper paint job, or imply do nothing.
In the last 2 pictures you see the outside of the disk (looking good) and the last picture is the poor inside of the disk (looking bad). I'll probably not change the disk.

What am I doing now?
I think I will buy a set of rebuilt calipers to get some traction... buy time and then I could rebuild the old calipers over winter.

Best, Martin

 

[werminghausen]

I just bought a set of caliper from amazon- A-Premium Brand.... Yeah right....premium. LOL. It will be cheap China stuff but I guess it can't be worse than the Napa caliper which stared failing after 2.5 years.
Anyhow I will keep the old castings and rebuild the old set over winter. Is there a reasonable source for our front pistons -8 pieces needed ?

Martin

 

[rdruss]

I just bought a set of caliper from amazon- A-Premium Brand.... Yeah right....premium. LOL. It will be cheap China stuff but I guess it can't be worse than the Napa caliper which stared failing after 2.5 years.
Anyhow I will keep the old castings and rebuild the old set over winter. Is there a reasonable source for our front pistons -8 pieces needed ?

Martin

I just changed out a NAPA caliper after 7.5 years and almost 50K miles, right rear, as it had seized and took out pads and rotor. Not too disappointed here. I put new NAPA caliper/pads and rotors back on.

 

[werminghausen]

rd: Yours were better then with 7years... I always liked the original casting of the NAPA rebuilds but I decided to take the risk of ordering cheap replacements (don't need to return my cores) but can keep the old casts and rebuild them over time myself.
I guess the cheap new calipers will be good for a couple if years... I hope at least. Then I have a rebuilt set on the shelf, if need be.

I guess the calipers are a weak part in these cars, unfortunately.

 

[AuSeeker]

rd: Yours were better then with 7years... I always liked the original casting of the NAPA rebuilds but I decided to take the risk of ordering cheap replacements (don't need to return my cores) but can keep the old casts and rebuild them over time myself.
I guess the cheap new calipers will be good for a couple if years... I hope at least. Then I have a rebuilt set on the shelf, if need be.

I guess the calipers are a weak part in these cars, unfortunately.

On new or rebuilt calipers for those people in the "rust/snow belt" or anywhere else for that matter, I would pull back the piston boots and and fill it with the same lube/grease used on the moving parts of the caliper to help keep water from penetrating in there next to the piston to avoid the piston from rusting as in Martin's photo, just make sure the lube is rubber safe.

 

[rdruss]

[MENTION=149207]AuSeeker[/MENTION], probably a good idea, similar to keeping the slider pins lubed.

 

[MikeinNH67]

Let's hope replacing those parts will end you brake saga for awhile. Looks like a smoking gun to me.