navdeepasi

Hi all,

This weekend I got around to changing all the shocks/springs with monroe quick-struts, the stabilizer link bars, as well as all 4 calipers, rotors and pads.

The suspension feels great.

However I have a problem with the brakes. The reason I changed the calipers in the first place was because one caliper was stuck, the pads on the left driver side were worn but right front were almost new. So I just changed all the calipers because that caliper was stuck, and the boot was pretty badly torn.

Before all the work the brakes were very squishy and most of the braking would occur at the end of the pedal motion, but still had a bit of resistance throughout, just more at the end.
After the work, the pedal goes to the floor when the car is on and near the end I get resistance and it brakes. It pulls left when I brake hard, and I can see brake dust on the front left wheel, but not really any of the rest. When the ignition is on, but the engine is off, it builds up a bit of resistance at the top of the pedal motion, but still not that much, and then it goes away once the engine is on (that's when it goes straight to the floor then gets resistance)

First thing I did was re-bleed the brakes, rear right, rear left, front right, front left. There was no air in the line at some point and I pretty much did it twice. I did not let the fluid drop below the min level as there was 3 of us doing it. One person pumping, one person controlling the bleeder, and one person adding fluid.

I'm really lost as to what the problem could be. I know the fluid is getting to the caliper since it's definately coming out of the bleeder. Everything is installed correctly, the bleeders are above th banjo bolts, there's no leaks I can find. I don't think it's the master cylinder since I get pedal feel towards the end (from my understanding a bad master cylinder would have the reverse problem).

Any thoughts? I'm thinking maybe I should take the calipers off, get someone to hit the brakes and push them calipers out, then push them back before re-installing and then try bleeding again? A lot of posts suggest issues with the master cylinder but I don't think that is the issue since it doesn't loose pressure at the end (i.e., if I'm stopped with the brakes on, it doesn't roll forward and I don't have to pump for it to stop, it will stay stopped but just at the end of pedal motion)

Cheers. Any help is much much appreciated

ES300NZ

sounds like the brake booster is stuffed, or leaking badly. but it could also be
- an issue with the master cylinder,
- the ABS unit.

fastnoypi

how low did the brake fluid reservoir get while bleeding the brakes the first time?

It sounds like you have air trapped in the ABS unit. I'm not familiar with the method Toyota/Lexus deals with this but other manufacturers plug in and pulse the ABS unit to assist with the bleeding.

pauloil

you did a good job with home bleeding, so take it in for professional help to clear the abs

navdeepasi

What could the problem be with the abs unit? would this cause the pulling issue (seems like front left is braking the hardest)? Any way to take care of this myself? I spent so many hours fixing everything up I'd really like to get the satisfaction of completing it myself.

navdeepasi

I never let the fluid get to the point of letting air in the master cylinder. It was never below the low level. Any idea how I can get the air out of the ABS unit myself? Now that I think about it the first time i hit the brakes it seemed like the abs went off prematurely, didn't really happen again.

navdeepasi

Anyway to diagnose one from the other?

LeX2K

Brake booster cannot cause a soft brake pedal and I've never seen an ABS unit do this either. So in my view you only have two possible issues, trapped or a bad master cylinder. Your symptoms sound more like a bad master.

There is another possibility a collapsed brake lane will cause a soft pedal but the mount your pedal is sinking seems a bit much for a bad line to be causing.

navdeepasi

I found this pdf on draining the abs, does this look right for a 97 es300? here is the linnk: https://www.google.com/url?sa=t&sour...WwS8tT-Zgb4yoA

navdeepasi

If there was a collapsed line would fluid still come out when I open the bleeder?

LeX2K

Yes a line can collapse internally which means it will balloon under pressure. It's not very common though. I've never had to bleed an ABS unit even when the system was completely drained, worst case I went on a gravel road at low speed and stomped on the brake to get any air to move out of the ABS unit.

ES300NZ

it's a strange set of symptoms.
- a bad hose might explain it, if it was expanding.
- the thing that gets me is it sounds like there was an issue already, because he started with an imbalance in his first prose.

fastnoypi

Hmm, it does sound like you properly bled your system, but your symptoms suggest air in the line.
One other thing is to check your brake booster vac hose. If it is disconnected from the vac source or the signal is weak, it can be difficult to operate the brakes.

Sorry, i don't know how to cycle the ABS unit yet on a Toyota/Lexus. On a Subaru, they have a diagnostic harness with grounding pins to cycle the abs unit if the Subaru Select Monitor is unavailable.
I'm still researching if Toyota has a similar procedure for the DIY'er. If you come across the procedure..please share.

mitmaks

Perhaps you have air in master cylinder, might have to bench bleed master cylinder.

ES300NZ

I was thinking about this, this morning.

- I bet one chamber in the master cylinder has stopped producing as much pressure as it used too, so one side is locking up long before the other even develops pressure.