Low brake pedal?

How many vacuum lines are their? I will check those today. Im familiar with the one coming off the vac pump. Any way to check these? Other then pulling them off.
 
Over the weekend I went to replace the wheel cylinders in the rear...that turned from a $20 2 hour project to $250 2 day project. Everything in there was rusted and worn so I landed up replacing the wheel cylinders, pads, adjusters , drums & all new spring hardware. Still the brakes are the same with no change. We bled the brakes 5 times on each wheel.

How often are new master cylinders bad from the factory? Mine is only a couple weeks old and I noticed some oil around the rubber that is between the master cylinder body & the reservoir. By the locatioin of the oil being that its under the reservoir I don't think its from spilling over the edge.

That ABS module that is under the master cylinder on a 94 2500 2X4....anyone got a part # for that? I've searched all my local parts houses and nobody can find a replacment.
 
It happens had one bed one right outa the box before at the shop. But did you properly bench bleed the master before you installed it?
 
I gave it a good try. The directions said that your done when all your able to push in is "up to 1/4". That never happened for me. After 30 minutes of me and my buddy rotating pushing duties we were still able to push our dowel all the way in until it bottomed out. At that point the bubbles were very minute. Just seemed like the bubble we were seeing at the 30 minute mark were possibly from the force of the fluid being pushed back into the reservoir.
 
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It isn't common for masters to be bad unless the system wasn't taken care of but it is possible, I would of went the cheaper route and grabbed one from the junk yard though.

Try this... With the truck turned off, pump the brakes to build up pressure and make the pedal really tough to push. Once it get tough, hold the brake pedal down and turn the truck on. If the brake goes to the ground, then your brake booster is fine.

Edit: Have you checked your front brakes at all? Beside bleeding them that is
 
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Also forgot to add your new master should of gotten noticeably harder to press in, one of two things here: A) you didn't bleed it right B) the unit wasn't built right
 
ChuMaDD said:
It

Try this... With the truck turned off, pump the brakes to build up pressure and make the pedal really tough to push. Once it get tough, hold the brake pedal down and turn the truck on. If the brake goes to the ground, then your brake booster is fine.
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Not tryin to be an ass but how does this tell you the boosters condition. The booster is a mechanical piece, how does turning the key on do anything. The booster depends on the vacuum from the engine to operate.
 
I meant turn the key and start the engine if there is a vacuum leak it will bled out somewhere it has happened to me with my cc servo vacuum line gave a spongy feel
 
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Ok. That makes a little more sense. But to find if the booster is holding vacuum you have to isolate it from the rest of the system. If you start and run the engine for a minute then shut it off,then go and try to unplug the check valve from the booster if it has a vacuum then chances are its good. Also check the one way check valve ( the piece of plastic that fits into the booster) it should be a tight fit and sealed. Next cap off that line and have a vacuum gauge on the rest of the system to check that 1. its pulling proper vacuum and 2. that it is not leaking down. You can also check the vacuum with everything hooked up and engine running to see if the vacuum pump can keep up with the demand while pumping the pedal.
 
Is there a reason as to why you can't bleed a new master cylinder while it's on the truck? It would save my hands from getting sore from pushing on a dayum dowel for 30 minutes solid.
 
It should only take 4-5 pumps when it's on the bench in a vise... Your bleeding it correctly right?
 
9 LIVES said:
Is there a reason as to why you can't bleed a new master cylinder while it's on the truck? It would save my hands from getting sore from pushing on a dayum dowel for 30 minutes solid.
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Nope. That's how I usually do it.
Red_Rattler said:
It should only take 4-5 pumps when it's on the bench in a vise... Your bleeding it correctly right?
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Usually. Just so as you get the big bubbles out. Slow and easy. Fast pumps cause tiny bubbles. After you bleed the MC open the rr bleeder and gravity bleed it for a few and then do the others.
 
Red_Rattler said:
It should only take 4-5 pumps when it's on the bench in a vise... Your bleeding it correctly right?
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I follow the directions that come with it. I put it in a vise...I use a long dowel and push slow and steady inward till it bottoms out. I wait 10-15 seconds and do it again....and again until the bubbles are mostly gone.

It says you should stop when you can't push your dowel in any further then 1/4". 30 minutes later we were still able to push it in all the way.

The first unit was a rebuilt unit. It did the same thing so I brought it back to Oreilly's and bought a new unit. It did the same thing so I left it alone:doh:
 
The kit is worthless. Use your fingers to block the ports when you release it. Makes a small mess but 99% of the fluid can be caught in a catch pan.
 
9 LIVES said:
Update: I put a reman master on.....that didn't help. I put a new one on and it didn't help either. While coming to a stop if you pump pump pump rapidly the brake pedal gets hard as steel and won't stop the truck until the pressure bleeds off the pedal (within 4-5 seconds).

I didn't get a chance to bleed the air out of the brake lines yet seeing that 3 of the 4 air bleeders broke off! That's going to be fun to fix :doh:

I took the rear hubs off and all looked well in the rear. Other then the adjuster is seized up.
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if you get a few full pumps on the brakes the vac will not keep up , i would say the rear brakes are out of adjustment or drums and/or shoes are worn out. my 2 cents
 
winkdemon said:
if you get a few full pumps on the brakes the vac will not keep up , i would say the rear brakes are out of adjustment or drums and/or shoes are worn out. my 2 cents
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Yeh, I think somethin about the rear brakes.was mentioned around the 3rd reply..
 
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