1992 GMC Sierra NEED ADVICE

BLKNGLDSTEEL

MEMBER
1992 GMC SIERRA
V8
4WD
AUTOMATIC
18,600 MILES

I HAVE A 1992 GMC K1500 XC AND I PUT A DISC BRAKE CONVERSION ON IT BUT BEFORE I DID THAT A BUDDY SUCKED OUT THE OLD BRAKE FLUID FROM THE REAR RIGHT TIRE. NOW THAT EMPTIED THE MASTER BUT I ASKED HIM TO BARROW THE BLEEDER KIT BECAUSE I CAN'T GET A HARD PEDAL. SO HE BROUGHT BACK AND I STARTED TO READ THE INSTRUCTIONS AND THEY STATE NOT TO OPEN THE BLEEDER AND START PUMPING. IT COULD DAMAGE THE SYSTEM, YOU ARE TO PUMP IT UP TO 10 IN. HG AND NOT TO GO PASS 20IN. HG. SO I'M WONDERING IF HE COULD HAVE DAMAGE SOMETHING AND THATS WHY I CAN GET A HARD PEDAL. IF SO WHAT WOULD IT BE THAT WAS DAMAGED?

3 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok first fill the master with fluid and then go open a bleeder you can start with the right rear and then left rear and then right front and then left front. So anyway open the right rear bleeder and leave it open till you get fluid ok. Now do this at each wheel one at a time. Now keep the master full while doing this. Now after that get some one to pump the brakes and bleed like you would normally and just don't push it all the way to the floor as you bleed put a 2x4 between the floor and the pedal to keep it a couple of inches off the floor and see it that takes the air out if not you may have a bad master cylinder. Let me know how it goes ok.

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Friday, November 21st, 2008 AT 11:18 PM

BLKNGLDSTEEL

MEMBER
6 POSTS

OK WELL I TRIED THAT AND STILL NO PEDAL. I PUT A NEW MASTER CYLINDER ON AND BENCH BLED IT THEN BLED THE SYSTEM AGAIN, STILL NO PEDAL. SO ASKED SOME ONE AND THEY SAID I SHOULD HAVE GOT SOMETHING TO UP THE PRESSURE TO THE BACK BRAKES. DRUM BRAKES WORK WITH 600 -800 PSI AND DISC BRAKES NEED 1200-1400 PSI. SO I WAS TOLD TO GET A NEW DISC/DISC PROPORTION VALVE. DOES THAT SOUND RIGHT? I HAVE NEVER HAD A PROBLEM BEFORE WITH BRAKES. THIS IS DRIVING ME NUTS!

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Saturday, November 22nd, 2008 AT 11:15 AM

RACEFAN966

MECHANIC
5,029 POSTS

Yes 4 wheel disc run a different valve the disc/drum. I would go to SSBC (stainless steel brake company) and check out there valve for a 4 wheel disc system. Hope this will be helpful.

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Saturday, November 22nd, 2008 AT 7:45 PM