Author Topic: Bleeding breaks?  (Read 5332 times)

75bowtie

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Bleeding breaks?
« on: August 19, 2001, 10:49:00 PM »
I am trying to bleed my breaks, and I am having a heck of a time. I have a 75 silverado with power breaks.I replaced the pads/shoes and calipers and cylenders.  After I bleed the breaks the peadle still drops to the floor.  


Offline bigblock73

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Re: Bleeding breaks?
« Reply #1 on: October 09, 2001, 12:58:00 PM »
I know some of these might sound obvious, and I am in no way trying to insult you, but people do forget...

1.  Have you checked your brake hoses for leaks?  How about the hard lines?

2.  Did you re-fill your resevoir after bleeding them?

3.  How are you bleeding them?  I open the bleeder, have a friend press slowly on the pedal two or three times but not releasing on the last one, I then close the bleeder and my friend lets go.  I then go to the opposite side and repeat this.  I do this until the pedal feels firm.

4.  Is the proportioning valve working correctly? (this might not apply since I have not had one go bad and don't know what will happen if it does).

Good luck!

Jeff

'73 swb 2wd

73-87.com

j in la

  • Guest
check for leaks
« Reply #2 on: November 06, 2001, 10:21:00 PM »
i agree with bigblock, i am a mechanic and i have installed new wheel cylinders and found them pouring puddles before leaving the shop.


Creeper

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Brake problem
« Reply #3 on: January 05, 2002, 01:22:00 PM »
First of all, you more than likely have a lot of air in the lines, being as you replaced calipers etc. Her is the correct procedure to bleed......get a buddy, top up your master cyl, with bleeders all CLOSED have your buddy pump until the pedal gets stiff, starting at the passenger rear, MAKE SURE BUDDY STILL HOLDS THE PEDAL AND DOES NOT RELEASE, crack the bleeder screw, pedal will drop and bubbles will come out, repeat until strictly fluid comes out, top up master again, and repeat procedure on drvr rear. then pass frt and finally drv frt. If you still have a problem, then you have a faulty vacuum booster.
your proportioning valve is not the problem. If your rear brks were locking up before your frt then it would be the problem, but this is not the case. Good luck.


84 K10 Silverado

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Brakes
« Reply #4 on: January 22, 2002, 11:15:00 PM »
You could also have a bad Master Cylinder.


Offline 84 silverado

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more on brakes.....
« Reply #5 on: January 23, 2002, 12:03:00 AM »
when I do work like you did at the shop this is my "usual" routine. I start by replacing the fluid in the master cylinder with fresh shtuff(you'll understand why in a bit) I do the front calipers first. Install the pads in the brackets and re-install the new calpiers with the bleeders OPEN. It makes a mess but I like to gravity feed my system BEFORE I pressure bleed it. This also allows a bit of old fluid to be flushed out while it makes a mess on your floor(draining old fluid/new fluid on the way) While the front is puddling on the floor, I do the rears. Replace the wheel cyclinders and install the NEW hardware(you did replace the hardware right?) shoes, etc, etc. All while the bleeders are still open and dripping on the floor. Once you have the rear shoes installed shut the beelders off to the front. the air will pretty much be gone by now since the bleed screws are on top of the calipers(air goes up and out) Adjust the rear shoes so they drag very slightly against the drums. When you get the drums on and adjusted good, close the rear bleeds. As mentioned before, start at the right rear brake to pressure bleed. The reason for this is that it's the furthest point from the M/C and hardest to bleed. From there, circle around from L/R, L/F,R/F amd you should be done. Oops, don't forget to add fluid to the M/C before you start to foot bleed the system If you don't you won't have enough fluid to last and it'll fill the lines back up with air and your screwed all over.
 Now, if you've already gotten the air out and have fluid at all four corners, you may just not have it adjusted right at the rears. If they're not out far enough you'll have a large amount of pedal travel because the wheel cylinders have to move the shoes so far and it takes extra fluid to do this. Check for the contact and slight drag at the back and see what you have there. I've seen alot of mis-diagnosis on brake system's for what would've been a simple adjustment. Good luck, Bill


Offline 83chev4x4

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Re: more on brakes.....
« Reply #6 on: January 24, 2002, 03:56:00 AM »
an easy way to bleed the brake by your self is to open the bleeder screw and put a hose going in to a cup with brake fluid in it. then just pump the brake pedal slowly.it will blow the air out and suck the brake fluid in. there is hardly any mess and easy to do. it will take a while to it. but if always use a friend. TJ


mike

  • Guest
brakes
« Reply #7 on: February 24, 2002, 09:18:00 AM »
with the truck running, pull the vacuum hose off the power brake booster.  If the engine rpm changes it could have an air leak internally or be bad. wheel cylinders, pistons, does it pull to one side? Is there ever and brake fluid on the inside of the tire when you are done driving?  


Offline 79mc

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Re: brakes
« Reply #8 on: April 10, 2002, 06:24:00 PM »
I once had proportioning valve trouble. The problem was that the master cylinder was allowed to run dry in the front or back reservoir (can't remember which). The little "pin" that sticks out the end of the prop. valve was extended way out, which would not allow fluid to the back(?) brakes. It's been a while and I can't remember which end of the truck I wasn't able to bleed. To check this locate your prop. valve (it should be bolted to a crossmember just behind your radiator). Remove the rubber cap on one end (seems like the cap was on the drivers side) then have a friend cycle the brake pedal. The little "pin" should cycle back and forth slightly. If it sticks ut about 1/8" or so and does not cycle, hold it in with a screwdriver (I used welding vice grips, but there isn't room on a 4wd DON'T OVER TIGHTEN THE GRIPS) Try to bleed if it seems better remove the vice grips on the pin and check its location. It should stay in (nearly flush) if it does put the cap back on and finish bleedind. HTH. If anybody disagrees please post. It has been a while since I had to do this and don't want to post bad information. Ialso use the gravity bleed procedure.

DougV>

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 

         


Offline 79mc

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Re: brakes
« Reply #9 on: April 10, 2002, 06:27:00 PM »
PS you probably know but there is a left and right to calipers. Make sure the bleeders point up. I don't mean to insult you. I once had this problem come into my shop and didn't relize the problem right away.

DougV>