Author Topic: Bleeding front brakes (Read 4780 times)

brads1978ta · « **on:** July 12, 2006, 09:55:48 AM »

I have a question about bleeding brakes with the Combination valve. How far does this pin in the end of the valve have to be depressed?? I built a tool for this problem but I don't think it went in far enough. I still don't have any fluid flow from the master cylinder. Any help would be great!!

Tin Indians Rule · « **Reply #1 on:** July 12, 2006, 10:14:14 AM »

Good reading on this subject here...

http://www.78ta.com/bleed.htm

brads1978ta · « **Reply #2 on:** July 12, 2006, 10:32:59 AM »

I have read this site it was my starting point. Where can I find the gm tool number j23709???

Tin Indians Rule · « **Reply #3 on:** July 12, 2006, 10:42:33 AM »

Did you install a new master cylinder? If yes, did you bench bleed it prior to installation? I understand that you are asking about the tool... but i don't think you need it just yet.

brads1978ta · « **Reply #4 on:** July 12, 2006, 11:30:44 AM »

Yes I did bench bleed the Master cyld. No bubbles !!

Tin Indians Rule · « **Reply #5 on:** July 12, 2006, 01:09:53 PM »

Have you bled the Master cylinder at eack resevior by pumping the brake pedal up and loosening the fitting where the brake lines go into the MC to check and see if you have fluid pressure there?

brads1978ta · « **Reply #6 on:** July 12, 2006, 01:35:47 PM »

Yes sir, loosened the lines and it had pressure. with the lid off the Master it spewed up in both bowls. You dont have to loosen anything on the proportioning valve before you depress the pin do you?? How far do you have to depress the pin?

Banditboy21 · « **Reply #7 on:** July 12, 2006, 09:13:56 PM »

i was told by a brake specilist that u never do anything with the pin just leave it alone and i replaced my entire brake system and my brakes are fine but i would check out piratejack.com he has a good info website

Tin Indians Rule · « **Reply #8 on:** July 12, 2006, 11:39:11 PM »

I've never had to push the pin either. I had entire brake systems off before and once assembled with good components all I've ever had to do was
Make sure the resevoir was full of clean fluid and the cap on with the clip over it
Put a buddy in the drivers seat and have him pump the brake pedal a few times and hold it down like he was applying the brakes.
While he is holding the brake pedal down loosen a line fitting at the MC and have him push the pedal to the floor when it starts going down.
Hold the pedal on the floor and tighten the line fitting.
Repeat for the other line fitting going into the resevoir. Check your fluid and then do the same thing for all four wheels starting with LF, RF, LR,and do the RR last. Each time pump the pedal really firm and push to the floor and hold it. tighten the bleeder valve and release the pedal. As you get the air out of the line the fluid pressure will reset the pin and turn the light off on the dash. If you are not getting fluid out of the bleeder valves at the wheel they might be rusted/corroded closed. Remember to never open the system unless the pedal is going down with firm pressure from your foot and never allow the pedal to come up on its own with a fitting/bleeder valave open. Aslo, keep the MC lid on with the clamps but keep an eye on the fluid level as you bleed. Not sure if you needed all this or not... But this should resolve your problem provided the MC is good, the rear brakes are adjusted tightly and the shaft between the Booster and MC has not be tampered with. NEVER ADJUST THE ROD THAT WORKS THE MC... :cry:

brads1978ta · « **Reply #9 on:** July 13, 2006, 09:28:34 AM »

Thanks again for the posts!! Ok I have a new AC Delco MC, Bench Bled,
new fluid. I replaced the combination valve also. What started this problem was the front right caliper was grabbing, not releasing. I replaced the caliper and when I was bleeding the brakes I noticed I didn't have any fluid coming out of the brake hose. I then replaced the combination valve. still no fluid. then I read that the pin on the valve had to be depressed to get fluid to the front brakes. "In the past I never had to press the pin to bleed the brakes either". I either have a stopped up or crimped line somewhere. This afternoon I am going to check the drivers side caliper to see if I have fluid /fluid pressure there. If I do Its a line going to the other side or if I don't its a bad combination valve.

Eagle 1 · « **Reply #10 on:** July 13, 2006, 09:54:46 AM »

If the caliper is grabbing and not releasing, most likely its the rubber hose that hooks to the caliper.
What happens is over time the lining in the hose breaks down and starts to callapse which will cause the calliper to not release. A word of advice, if you replace one, replace both.

brads1978ta · « **Reply #11 on:** October 20, 2006, 04:10:05 PM »

Just to let you know the brake line was the problem. It was as best I could tell the original hose. When I finally got it off the brakefluid flowed well. Bled the whole system and the brake light reset itself. Thanks again for the help. Now I have a Transmission pan leak to fix. NEXT!!!!!!