94 SC bleeding brakes, - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 12-13-2007, 12:17 PM   #11
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Neither should cause that. Is the MC rebuilt or new? Did you bleed it like this:

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Originally Posted by willwren
The kit will come with two new pins to hold the reservior to the MC, as well as two green fittings to screw into the MC, and two clear hoses. The instructions are mostly good.

Put the MC in a vise (upright) with the vice jaws on the bottom of the mounting flange, with the flange facing you so you can push on the piston (simulate the brake pedal). Install the green fittings and tubes. Fill the res (you must plug the outlet for the PMV reservior fill). Go about half full on the MC, but you may have to tip/tilt it to get the fluid to the front chamber also.

Put it back in the vice with the piston/flange facing you, and run both hoses into a small container of brake fluid, with the ends being under the surface (fully immersed).

Push the piston all the way in, hold for a couple seconds, and release. Wait for the bubbles in your little container to dissipate so you don't suck them back in on the next cycle. Repeat this process several times until there'* no more air. At that point, you can lift the tubes out, but leave them on. They'll keep it from leaking (make sure you hold them up so they're higher than the reservior as you install the MC). Bolt the MC on to the booster, then pull your plug underneath quickly, and hook up the 3/4" feeder to the PMV reservior, then remove the green fitting and tube closest to the firewall, and re-connect that brake line (rear first, it'* easier). Then do the same for the forward fitting.

Bleed the entire system.
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Old 12-13-2007, 12:31 PM   #12
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thank you for replying, yes i have followed the instructions, the new MC is probibally a reman,i have bleed brake systems successfully in many cars in the past, my uncle'* both have shops which i grew up in ?? my uncle seems to suspect the abs controller has air stuck in it or a proportioning valve is partially stuck closed , because i can get fluid out of three wheels by gravity bleeding,but i cannot get any fluid out of the front ds???please help
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Old 12-13-2007, 12:34 PM   #13
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Drive the car a short distance and come back. The pump in the ABS/TRaction unit (PMV) will come on for a self test, and the PMV should auto-bleed.

Normally nothing is reqiured out of the ordinary for these. A pressure bleeder may be your best bet right now as well.
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Old 12-13-2007, 12:39 PM   #14
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would it be safe to take the car for a drive if i have no brake pedal at all?? it doesn't want to build a pressure.
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Old 12-13-2007, 01:29 PM   #15
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Stick to your neighborhood only, very local, and use the e-brake. You may not need to go past the end of your driveway and back.

This advice is a shot in the dark in case something is stuck or wrong inside the PMV. The PMV is designed as a fail-safe device. Any failure inside it should not affect normal non-abs operation of the brake system.



Answer these for us:

If you have no pedal at all, are you getting any air out of the bleeders?

Is the end of your bleed hose immersed in brake fluid in a clear container so you can see air bubbles?

How much (in ounces) brake fluid has run through the system in your bleeding attempts?

Is the problem worse than before?

Is the reservior properly mounted flush to the rubber seals?

Is the clamp on the ABS reservior feed (3/4" line) tight?

Are both main brake lines on the driver'* side of the MC properly tightened and rust-free?

We have to assume your MC is good since you bench-bled it and saw the fluid circulating with no bubbles.
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Old 12-13-2007, 02:04 PM   #16
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i had some air bubbles come out of the rr for the first ten min of pumping ,i have used up 5 liters of fluid so far ,the mc reservoir appears to be snug and tight to the rubber seal ,the brake lines on the car are in good condition ,the car came from the south not too long ago ,i originally bought it because it was in excellent shape in the undercarrage,??
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Old 12-13-2007, 02:06 PM   #17
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what is pmv???
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Old 12-14-2007, 01:18 AM   #18
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Quote:
Originally Posted by Brad_94
i had some air bubbles come out of the rr for the first ten min of pumping ,i have used up 5 liters of fluid so far ,the mc reservoir appears to be snug and tight to the rubber seal ,the brake lines on the car are in good condition ,the car came from the south not too long ago ,i originally bought it because it was in excellent shape in the undercarrage,??
Where did this 5 liters go? All out the RR? If air is trapped in other runs, you may not be able to build up sufficient pressure to get a good solid stream of fluid to come out the first run (RR). When the air quit spitting after 10 min, it was then time to go to the LR. If the fluid is coming out anywhere else but the bleeder you are opening, that needs to be addressed before you will be successful.

It is not uncommon to get no significant pedal until you are bleeding the last line (usually the LF) I have experienced this, not believing that the pedal could be so soft until the very last minute, but then as the last spits of air are bled, the pedal firms up very quickly. Air trapped anywhere in the system can cause a soft pedal until removed.
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Old 12-14-2007, 12:48 PM   #19
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i had gravity bleed each wheel until i saw a steady stream ,i usually stopped when i had seen 750 ml in the pan,when i was bleeding each wheel, i moved in sequence every 15 min but i saw very little pressure or air bubbles, i find it strange that there is very little pressure?? is there a separate bleeder screw for the abs controller??
thanks for the help
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Old 12-14-2007, 01:38 PM   #20
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Forget the PMV (ABS unit under airbox). The odds of that being a problem if it wasn't before are so remote they're not worth discussing here, and no, there'* not a bleeder screw for it.

There is no failure in that PMV that can cause issues with the basic braking system.

Discussing this with jr's3800 on the phone last night, we both feel that assuming you did everything above as stated, your most likely issue is a bad MC off the shelf. It happens.

It would take less time to go exchange it at this point than to fight the system any longer.

Pick up some more brake fluid while you're at it. Cheapest dot3 you can get.
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