Soft brake pedal

[seafish]

So did you actually TEST your ABS unit as described int he video??

 

[PMedina]

So did you actually TEST your ABS unit as described int he video??

Yes, I tested both ports. The piston on both moved at least 3/4". I'm assuming both cavities had to fill with fluid as the pedal moved close to the floor before I would get any braking action.

 

[seafish]

Yes, I tested both ports. The piston on both moved at least 3/4". I'm assuming both cavities had to fill with fluid as the pedal moved close to the floor before I would get any braking action.

K...I need to do this test on 2005 Jeep Liberty CRD....Thanks!!!

 

[Ozymandias]

Thanks for the Video, I tested mine accordingly and nothing moves*.
But can still floor the pedal.. after pressure bleeding the ABS and the whole brake at least six times, run 4 quarts of DOT3 through.

I hoped for it to move to find the unsolved problem.

 

[Rowdy Dalton]

Sounds like there is air, somewhere in there?

.

 

[Ozymandias]

Sounds like there is air, somewhere in there?

.

No idea where, I spent another four hours bleeding 2 gallons through that system today*.
Tried everything with the Autoenginuity bleeding sequence, and so on.
When I close electronically the isolator valve(s) the pedal is rock solid until that valve opens (default open), then it goes only down.

*Update: And haven't seen a single drop of air coming out at any corner, not a single bubble, nothing, just pure fluid. Turns me nuts...

 

[seafish]

Will unplugging the ABS pump fuse fix that??

Your an extremely experienced driver...ABS may even be more of a nuisance then a help to you...just an idea!!!

That said, I am sure that you must have tested the master cylinder itself for bad seals??

 

[Ozymandias]

Master Cylinder I replaced* today... to no avail, but o well, this isn't the most expensive part.
Bench bleeded of course prior to install.

The ABS isn't actively interfere with the brake, it's a passive problem.
Switching it off doesn't change the behavior.
And because of the electronic brake distribution of the Gen3 it can't be taken out just like in the old ones.
And actually I like that added safety, ABS saved me more then once from crashing in my wilder years.

*Just because of the maybe factor.

 

[Rowdy Dalton]

Master Cylinder I replaced* today... to no avail, but o well, this isn't the most expensive part.
Bench bleeded of course prior to install.

The ABS isn't actively interfere with the brake, it's a passive problem.
Switching it off doesn't change the behavior.
And because of the electronic brake distribution of the Gen3 it can't be taken out just like in the old ones.
And actually I like that added safety, ABS saved me more then once from crashing in my wilder years.

*Just because of the maybe factor.

I'm out, because the master cylinder replacement was my next idea. Except for possibly worn rubber brake lines.

.

 

[Ozymandias]

I'm out, because the master cylinder replacement was my next idea. Except for possibly worn rubber brake lines.

.

The lines look good so far but I'm going to change them next anyway.
When I watch them close when a helper floors the pedal I can see some swell to them but at their full length equally. Doesn't look bad to me but maybe, one never knows.

 

[Ozymandias]

Okay, I replaced now the whole brake system and still the exact same pedal feel.
What a waste of money and time.

 

[Rowdy Dalton]

I hate to say this but, maybe it's time to take your truck in to a brake shop.

 

[Ozymandias]

The problem is that nobody wants to tell me if he's able to push his pedal to the floor with let's say 150lbs of pressure applied to it.

Like I said, I push it with a raising force to a certain point like it should be - and from there on it can be pushed down with very much the same force.

I found only ONE single post in a forum where a guy said that he can do the very same.

 

[Rowdy Dalton]

The problem is that nobody wants to tell me if he's able to push his pedal to the floor with let's say 150lbs of pressure applied to it.

Like I said, I push it with a raising force to a certain point like it should be - and from there on it can be pushed down with very much the same force.

I found only ONE single post in a forum where a guy said that he can do the very same.

Update??

 

[Ozymandias]

None, still haven't found someone that is willing to walk out to his truck and push his pedal down as hard as he can.

 

[petersonj]

None, still haven't found someone that is willing to walk out to his truck and push his pedal down as hard as he can.

@Ozymandias , are you looking for someone to test a 2004.5 year model truck, or would a 2002 second generation truck do?

Anyway, for what it's worth, the brake pedal on my truck only travels 3 to 4 inches maximum (no where near the floor) whether or not the engine is running or the engine is off and the the brake pedal has been pressed several times to bleed off the hydroboost accumulator. All tests done with about 150 pounds of foot pressure as you asked.

- John

 

[Ozymandias]

@Ozymandias , are you looking for someone to test a 2004.5 year model truck, or would a 2002 second generation truck do?

Anyway, for what it's worth, the brake pedal on my truck only travels 3 to 4 inches maximum (no where near the floor) whether or not the engine is running or the engine is off and the the brake pedal has been pressed several times to bleed off the hydroboost accumulator. All tests done with about 150 pounds of foot pressure as you asked.

- John

Thank you, that is about what the 02 of my buddy in Tacoma does too.

Every input helps!
But best bet would be a 3rd Gen, especially with the upgraded ZF power steering pump.

 

[Superdawg]

Hi Ozy. Just read this thread. I got a 2004.5
Engine off, pump the pedal 3 times, pedal goes down about 2-3", rock solid. 150 lbs pressure, not moving.
Engine on, pump pedal three times, pedal goes to the floor with pretty light pressure.

ZF pump, rebuilt brake booster unit.

 

[petersonj]

Engine on, pump pedal three times, pedal goes to the floor with pretty light pressure.

Interesting. So, it looks like your brake pedal operates the same as @Ozymandias. Where the heck is the brake fluid going?! Is this supposed to be normal brake pedal operation? It sure doesn't seem like it should operate that way - but, who knows.

- John

 

[Ozymandias]

Hi Ozy. Just read this thread. I got a 2004.5
Engine off, pump the pedal 3 times, pedal goes down about 2-3", rock solid. 150 lbs pressure, not moving.
Engine on, pump pedal three times, pedal goes to the floor with pretty light pressure.

ZF pump, rebuilt brake booster unit.

Thanks you very much, so I've a second input. Yours behave the same as mine.
Let's see if we get more people to walk out to their truck and fo the test.

In the end I spent a 1000$ for fixing what's not broken.