Help-brake Bleeding Issue-help!

[jnjboc]

folks, I need help.

began bleeding my RR(first caliper in the process) getting ready for the DE Wednesday in Nashville.
Put on the new racing pads. sucked out most of the old fluid from the master, but left fluid still visible in the master holding tank. Added new Motul 600 until the master was about 1/2 full.

Loosened my speed bleeder and began pumping about 10 times-no issue.

turned the ignition on and waited a minute(per revised GM specs on bleeding). began pumping again. after about 4 times, the pedal just went to the floor. there was no mild pressure sensation you get when bleeding.

My DIC was alternating: LOW BRAKE FLUID, SERVICE T/C, SERVICE A/H.

checked the master. the holding tank was about 1/3 full. added more Motul 600, locked down the speed bleeder, put wheel back on. cranked car.

I get NO pressure in the the brake pedal at all, no matter how many times I pump.

I am positive the master did not run dry. That's the one thing I always guard against.

Any thoughts? This is really not a good thing.......two days before a DE!

thanks.

[wtknght1]

I just normally open the bleed screw and do a real slow gravity bleed until the new fluid is in the caliper. Make sure the reservoir is full with new fluid.

Try clearing the codes in the DIC and then see if it comes back. Do you know how to clear the codes in the DIC without a Tech 2??

Hold down the "Options" button with your right thumb and then hit the "Fuel" button 4 times with your index finger. The diagnostics will start to come up on the DIC. Press the "Options" button until it reads off the number of codes for each category (PCM, TCS, etc) and then hold down the reset button to clear the codes. Do that for all of them. After that, hit the Metric/English button to come back to normal operations.

If that doesn't work, you'll probably have to get a GM mechanic or Tech 2 to fix the issue.

[DJWorm]

1. When installing the new brake pads; how did you compress the caliper pistons for the new pads and what was your proceedure....ie. did you vent the system when you did this ??

NOTE: When bleeding with Speedbleeders I only need 2-3 slow pumps to clear a caliper....NOT 10. In fact, I can bleed 2 corners (6 pumps total) before needing to refill the Master cylinder. The "pumps" should be slow and constant. Make sure you ONLY "open" the Speedbleeder 1/4 turn max.

2. NOTE: When using the Revised Brake Bleeding Procedure you need to
- bleed ALL 4 corners using the normal procudre first,
- then turn ON the ignition, wait 1 min. and bleed ALL 4 corners again,
- then turn OFF the ignition and rebleed ALL 4 corners a third time.

But first:
3. Reset the codes, then dissconnect the battery for 5 minutes, then reconnect.

Next:
4. It appears that you DO have air in the the system or a Malfunction.
- rule out a leak in the system first, check all 4 corners paying particular attention to the bleeder valves, a caliper piston seal leak, the flexible brake line connections, around the Master cylinder, the flexible brake lines themselves, looking for dripping fluid. Make sure everything is tight.
- Bleed the Master Cylinder (It's in the Service Manual).
- do a gravity flush and bleed at each corner.
- then attempt a normal bleed at each caliper.
- Perform the Revised Brake Bleed Procedure.
- If the above fails, you need to do a diagnostics check on the ABS using a Tech II Analyser

NOTE: when doing a gravity flush or bleeding a caliper always use a rubber mallet to dislodge any trapped air.

NOTE: When installing Speedbleeders the mating surface and threads must be clean and sealant used on the threads. The sealant must be reinstalled periodically, at least once a year and more frequently if you bleed more often. In addition the area around the bleeder must be kept clean and cleaned before bleeding. Speedbleeders are great little tools but I have seen a couple fail. If you constantly see air in 1 caliper it is either the caliper piston seal or a bad Speedbleeder

[jnjboc]

thanks for the quick replies guys!

All is working ok now.

I think my problem may have been that my speed bleeder was open too much? I had it open 1/2 maybe 3/4 of a turn.

After closing the speed bleeder on my first wheel(RR), I slowly pumped for awhile, and eventually got pressure back. Finished all wheels and there is very good, firm pressure now with the new pads.

I have not bedded them yet, but after pushing the pedal down approx. 3 inches, it's very firm..

DJ, great info. as always. regarding the compression of the pistons. I do it the only way I know(the way I was shown), I put an old pad plate over the two pistons, then using a very large adjustable wrench, compress the pistons. sounds like I am missing something as you mentioned "venting the system"........??

This is the 2nd time I have bled the speed bleeders-they are brand new. I did purchase some of the lubricant paste with them for re-application when needed...

[DJWorm]

Usually as brake pads wear the "extra space" is taken up in the system by adding fluid to the master cylinder reservoir in a well maintained car.

When changing to new pads (thicker) excessive system pressure can be applied to a closed system by compressing the caliper pistons in a now "overfilled system". This is especially true when the OEM flexible rubber brake lines have been replaced with non-compliant Teflon lined SS braided lines. This can cause damage to the Master Cylinder, system solinoids and the ABS, even burst the OEM rubber lines.

Normally the excessive pressure would be "absorbed" by the compliant OEM rubber lines or by removing some volume from the Master Cylinder reservoir and leaving the fill cap cracked open (be ready for the overflow mess).

Having Speedbleeders opens another option. They provide the ability to bleed off excessive volume & pressure while compressing the caliper piston.

[wtknght1]

That brings up a good point. I learned many years ago to set the brake fluid level to full with new pads and rotors and don't 'top off' the fluid. Just leave it where it is and don't add any more as the fluid drops a little due to brake/rotor wear. It won't drop more than about 1/2 inch anyway and if you add more, you'll have to use a turkey baster to suck some of the excess fluid out...or have a big mess!

[yankee0304]

Originally Posted by wtknght1

That brings up a good point. I learned many years ago to set the brake fluid level to full with new pads and rotors and don't 'top off' the fluid. Just leave it where it is and don't add any more as the fluid drops a little due to brake/rotor wear. It won't drop more than about 1/2 inch anyway and if you add more, you'll have to use a turkey baster to suck some of the excess fluid out...or have a big mess!

Just a little friendly advice from a auto tech...on vehicles with ABS, it is never a wise idea to force the fluid back out through the master. The crap that is in the lines has been forced into the ABS pump and many ABS Pumps have been ruined this way. I'd hate to see anyone on this forum make that expensive mistake.

[wtknght1]

What are your other options? When you compress the caliper pistons to make room for the new pads, the fluid has to go somewhere.

For the record, I've changed pads in Corvettes since 1990 and never had any issues - well over 200 pad set changes. I don't doubt that it could happen, but I've never had any problems.

[UstaB-GS549]

For the record, I've changed pads in Corvettes since 1990 and never had any issues - well over 200 pad set changes. I don't doubt that it could happen, but I've never had any problems.

I'm with you. Many years of just pushing back pistons with a heel bar behind the pads and no problems. If your brake fluid looks like sludge, the ABS unit may be already damaged.

[DJWorm]

Precisely, that's why the Speedbleeders offer such a great additional option to bleed the excess pressure and bake fluid volume when compressing the caliper pistons.

- Easy
- Simple
- Positive
- No mess (use a catch bottle)
- No air entrainment
- No back flushing to ABS
- No backflushing thru system solenoids
- No back flushing to Master Cylinder
- Enables running a full Master Cylinder Reservoir all the time
- No excess pressure

[KINGPIN]

Can somebody tell me(amateur) what happens if the master goes dry.

[DJWorm]

Air everywhere and it's a PITA to get out.

[corvette dave]

I'm with wtknght on this one. Keep it simple.
My numerous brake changes go back to 1985 for DE events with no problems forcing fluid back through the system. I never top off the master cylinder.

The talk is about how speed bleeders allow you to vent the caliper while pushing the pistons back. OEM will allow the same thing if you feel the need to do so.

If you are changing fluid frequently it stays pretty clean so a little back through the system should be fine.

[DJWorm]

Using an OEM bleeder is possible if you put pressure on the caliper piston first and then open the bleeder with pressure is on the system, The tricky part is closing the OEM bleeder before pressure drops off and not sucking any air......and you never can be sure with the OEM bleeders. It is a two person operation.

The Speedbleeders are just easier and are safer in regards to air intrainment. They allow it to be a one person operation.

[corvette dave]

DJ,
Let's say you do get a small amount of air back in while venting a OEM bleeder.
If you are bleeding the caliper it won't matter.
If not it could matter. I have never vented one.
Never used a rubber hammer either. No problems, although I think it is a good idea.
Why not as you hold the piston in, reach over and close the OEM bleeder? Why would this be any different than when someone pushes the brake pedal and when he reaches the floor the other guy closes the bleeder?
Seems more complicated than it needs to be.
Just going by past experience. Over 140 flushes and that many pad changes with no problems related to this topic.