trying to solve solve soft brake pedal since weekend

[alwaysFlOoReD]

That engine vacuum thing is interesting

Just keep an eye on the master fluid level...

 

[Uncle Gump]

I would throw the speed bleeders in the trash... put the standard bleeder screws back in and just gravity bleed the system.

 

[Paisano]

Doesn't gravity bleed take a long time ?
Plus, I have a slight incline in my brake line

 

[Uncle Gump]

You've already been working it for 4 days...

It really only takes minutes.

 

[Paisano]

Have to go back in to work tomorrow. Finish this in the evening after work or Saturday.
Seriously looking at one of the bleeder devices for the future.

Couple questions on MC bleeder kit with the plastic fittings and hose.
1. I can use this on MC installed in truck with reservoir in tilted position?
1. ok to bleed both master cylinder ports simultaneously?

 

[Uncle Gump]

I havent bled a master cylinder in 25 years.

Bolt it up... fill it up... wait for it to "gravity bleed" a
With a steady drip. Start the lines... have someone push the pedal down and hold it... tighten the lines. Done.

Don't over think this...

 

[Curious Hound]

Don't over think this...

That right there.

 

[Paisano]

Don't overthink it......That's actually good advice.
Auto repair can be technical. But not all the time.

 

[Paisano]

I replaced the bad speed bleeder today. I bled the installed master cylinder first until one large bubble was gone. Then I bled all 4 wheels until I saw no more bubbles.

Still slack brake pedal with no pressure. I even checked the brake pedal linkage to make sure nothing came loose. I don't get it. What is the problem?

 

[RobbieD]

I hate it, that this thing is fighting you so hard.

Brake work is not really complicated, and usually they just straight-forward work after repair or servicing. And, it does sound like you have done the work correctly.

Looking at things that you haven't mentioned doing, the actuating push rod coming out of the vacuum booster into the cylinder has an adjustment spec. You may be running into something that's not usually a concern.

Although easier done during the installation, you may want to check that this adjustment is not way out of whack. If it's too short, the piston in the master isn't being pressed far enough.

This is the section out of the shop manual that describes how to check and set the booster push rod for the correct length. This is from the '94 manual, but it should be the exact same for your '92.

You can make the gauge block out of cardboard, just measure and cut it carefully so that it's accurate.

 

[Paisano]

Robbie, Doing some reading on your booster push rod comments.........

 

[Uncle Gump]

So... do the brakes work and the brake pedal is just low?

 

[Paisano]

No. The power brakes don't work......just like earlier this week.
Brake pedal is firm when engine is turned off.
When engine is turned on, it's almost as if the brake pedal is in a state of 'free play.'
It's very loose. I've bled brakes successfully several times in the past.

 

[Uncle Gump]

But... does it apply the brakes and stop.

If the pedal is firm at the top without power assist... then brakes are functioning.

Do you have the rear brakes adjusted?

A poor (loose) adjustment there will make the pedal low. You will really see it when the power assist is working.

 

[Uncle Gump]

And just to clarify...

If the pedal travels more once the engine is started. The power assist is working.