bleeding brakes - 1992 - nothing at modulator
09-03-2015, 10:14 PM
#1
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bleeding brakes - 1992 - nothing at modulator
I picked up a 1992 6 speed about two months ago. I've been going through the full list of TO DO'S. Today I flushed fresh fluid through my brake lines, the old fluid was pretty dark.
Had no problem with the 4 corners
BUT
before getting to the bleeders at the wheels I tried to loosen the bleed screw on the prime pipe at the hydraulic modulator in the rear storage area and I got nothing to pump through...
Bad bleed screw? I didn't pull the bleed screw all the way out in fear of a brake fluid mess inside the car.
something wrong with the system? Not allowing pressure there?
I'm a fairly ambitions but not so experienced weekend wrencher. . . This could easily be something obvious but over my head. Like a "you forgot to..."
The brakes do feel rock solid. There was a some air bubbling at the front left when I bled it. The brakes may even feel a little tighter than before I started. BUT , why couldn't I bleed from that 5th bleed screw?
Had no problem with the 4 corners
BUT
before getting to the bleeders at the wheels I tried to loosen the bleed screw on the prime pipe at the hydraulic modulator in the rear storage area and I got nothing to pump through...
Bad bleed screw? I didn't pull the bleed screw all the way out in fear of a brake fluid mess inside the car.
something wrong with the system? Not allowing pressure there?
I'm a fairly ambitions but not so experienced weekend wrencher. . . This could easily be something obvious but over my head. Like a "you forgot to..."
The brakes do feel rock solid. There was a some air bubbling at the front left when I bled it. The brakes may even feel a little tighter than before I started. BUT , why couldn't I bleed from that 5th bleed screw?
09-03-2015, 10:19 PM
#2
Pluged with crap?
09-04-2015, 09:22 AM
#4
Team Owner
I believe that you have to have the ABS pump running to bleed the unit. That requires a GM Tech-1 scan tool with the additional brake module. There are probably some other scan tools (Snap-On has one) that will do the job.
Every time you start the engine and the car moves forward thru 2-3 MPH, the ABS pump does a self-test. For a few seconds, you will hear a buzzing noise behind the driver's seat. I think that test also circulates a small amount of fluid between the ABS pump and the master cylinder. Keep checking the fluid in the reservoir over a few weeks time to see if it darkens. You can easily suck out the old fluid from the reservoir and replace with fresh fluid.
Every time you start the engine and the car moves forward thru 2-3 MPH, the ABS pump does a self-test. For a few seconds, you will hear a buzzing noise behind the driver's seat. I think that test also circulates a small amount of fluid between the ABS pump and the master cylinder. Keep checking the fluid in the reservoir over a few weeks time to see if it darkens. You can easily suck out the old fluid from the reservoir and replace with fresh fluid.
09-04-2015, 11:57 AM
#5
im doing my 87 right now and i read that you do all 4 corners, RR, LR, RF, LF, then safely activate the abs pump and do it all again. I believe that you have to have the ABS pump running to bleed the unit. That requires a GM Tech-1 scan tool with the additional brake module. There are probably some other scan tools (Snap-On has one) that will do the job.
Every time you start the engine and the car moves forward thru 2-3 MPH, the ABS pump does a self-test. For a few seconds, you will hear a buzzing noise behind the driver's seat. I think that test also circulates a small amount of fluid between the ABS pump and the master cylinder. Keep checking the fluid in the reservoir over a few weeks time to see if it darkens. You can easily suck out the old fluid from the reservoir and replace with fresh fluid.
Every time you start the engine and the car moves forward thru 2-3 MPH, the ABS pump does a self-test. For a few seconds, you will hear a buzzing noise behind the driver's seat. I think that test also circulates a small amount of fluid between the ABS pump and the master cylinder. Keep checking the fluid in the reservoir over a few weeks time to see if it darkens. You can easily suck out the old fluid from the reservoir and replace with fresh fluid.
09-06-2015, 11:44 PM
#6
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thanks
I believe that you have to have the ABS pump running to bleed the unit. That requires a GM Tech-1 scan tool with the additional brake module. There are probably some other scan tools (Snap-On has one) that will do the job.
Every time you start the engine and the car moves forward thru 2-3 MPH, the ABS pump does a self-test. For a few seconds, you will hear a buzzing noise behind the driver's seat. I think that test also circulates a small amount of fluid between the ABS pump and the master cylinder. Keep checking the fluid in the reservoir over a few weeks time to see if it darkens. You can easily suck out the old fluid from the reservoir and replace with fresh fluid.
Every time you start the engine and the car moves forward thru 2-3 MPH, the ABS pump does a self-test. For a few seconds, you will hear a buzzing noise behind the driver's seat. I think that test also circulates a small amount of fluid between the ABS pump and the master cylinder. Keep checking the fluid in the reservoir over a few weeks time to see if it darkens. You can easily suck out the old fluid from the reservoir and replace with fresh fluid.
09-07-2015, 09:16 PM
#7
Le Mans Master
Just my 2 cents. Been 10 years since I bleed and replaced the ABS. But from what I remember I did not run the pump. I either pressurized the master with a pressure tank. Or I held the brake pedal down. But I think just from gravity it will just run out since it is lower than the master.
I think it's a strong possibility the bleeder is clogged. If you remove it, get a bunch of rags under and on the side of the pump. (Guess how know). I would check for the clogged bleeder first.
My 94 has a tube that runs from the side of the master down to the pump. I don’t think the 92 has that and have forgotten what the operational difference is. But if there is no tube, it may not run out (not sure).
I think it's a strong possibility the bleeder is clogged. If you remove it, get a bunch of rags under and on the side of the pump. (Guess how know). I would check for the clogged bleeder first.
My 94 has a tube that runs from the side of the master down to the pump. I don’t think the 92 has that and have forgotten what the operational difference is. But if there is no tube, it may not run out (not sure).