I had my calipers powder coated, and during that time, my whole braking system drained. Rebuilt the calipers, reinstalled them and bled them (not under power, didn't have an engine @ the time).

We then fired the engine, and still didn't have any brakes. Bled them again. They got better, but still weren't useable in daily driving. We bled them again tonight, and in the time it took me to give the car a quick bath, the brakes had gone out again.

Each time we bleed them, they're getting somewhat better, but it seems if we let it sit for a little while, the brakes lose all their pressure.

The way we're going, it seems that we could keep bleeding them, and eventually will work, but I wouldn't think that they would keep losing pressure if there wasn't a leak in the system somewhere. There aren't any noticeable spots under the car though.

Any thoughts?

 

Kinda sounds like a bad master cylinder to me. Are you losing any fluid?

 

check for leaks and I think you gotta bleed them with the ABS energized. leave the car runnin and bleed them all around then fill the master cylinder again.

 

I bet you have air in the ABS motor. I can see bleeding the whole system again in your near future...

remove your Airbox duct fron the MAF sensor. Connect a long clear hose to the bleeder screw, routed up to the engine hood lacth and then let it drop in to a container.. loosen up the bleeder screw, you should see some air or fluid go up the clear hose... go inside your car, turn the engine on and wait just a couple of seconds..your ABS pistons do a quick honing.. some air may come out at that moment... with the engine running bleed the sucker... the clear hose will pretty much give you an indication about how much air was trapped..


I noticed when I did mine that even the brake fluid has tiny air bubbles trapped in it... so keep pumping slowly till solid brake fluid comes up. dont forget to add more fluid to the master cylinder...

After you done with that one .... repeat the same with the other bleeder screw... once you done then you will need to bleed the rear passenger side.... rear driver side.... front passenger side and finally the front driver side...

In other words from the longest to the shortest brake line lenght....


Or you can spend the 30 bucks and get a mighty vac pump.... most guys here swear by it... I bought the one with plastic pump and it sucked... the brake fluid smell/fumes trapped in the hoses kills the pump itself.. the fluid never touched the pump but it slowly deteriorated till the plastic and valve seal was dammaged... and it was on the first time I used it...

I know they sell the mighty vac for bleeding brake lines but my local Sears never has it in stock


Maybe Napa has them...

Marvin

 

UNCU112, you have air in your system. DId you properly bleed each caliper? Are all the fittings secure and airtight?

While the Master cylinder is suspect it would be an rare coincidence for it to die suddenly. They tend to go slowly. Once they start to go, no amount of bleeding makes any improvement. Look elsewhere IMHO.

You need a quality bleeding tool. Don't waste money on those $10 elcheap jobs at the franchise parts stores. I purchased my first Mity-Vac in 1973 and I can say it has been one of the best tools in my shop. AS MArvin states the ($30)plastic one are not as good as the ($99) metal ones, but I still got many good years of brake jobs from the plastic version. I have had a metal HD version for the last four years and three brake jobs, a MC and countly bleedings, not to mention other applications. Aside from Mity-Vac there are other far more expensive and better brake bleed tools for pro shops if you have the money to invest. I don't.

 

I don't have any fluid loss, that I can tell. The last time we bled them was with the car running, and it seemed to make the most difference. The master cylinder has been off a couple times during our whole process too (Shock Tower Brace & new shock and spring installations).

I think we have been using a little cheapy deal from AutoZone or something to bleed them... if they've been using something other than a 10mm wrench to just loosen the valves. To be honest, I've just been the one in the car pumping the brakes, so I haven't seen the tools they've been using

I'll do some more checking around on it... maybe I can get one of those Mighty Vacs around here somewhere today. Thanks

Fred

 

"Master cylinder has been off" ...Ding. You never mentioned that before.

In addition ot the advice above, you may have got air in the MC. I can't say for sure, but you may need to bench bleed that MC to get all the air out. For example, one must bench bleed a new MC prior to install to get all the air out. While it is not 100% required, it would take consider work to get the air out.

Having a bud pump the brakes is a very good method if done properly, but if the calipers were off, the MC was off, you really have the opportunity to get considerable amount of air in your system and this will take a good amount of fresh fluid to purge the system. This assumes all the connections are air tight, too.

The more info you provide the better chance of getting useful info from this board.

 

In retrospect, I'm not sure if my "off" is the same as yours. The master cylinder was disconnected from the booster, not from the car or the attached lines. It was just unbolted, and swung to the side to allow access to bolts it was covering. Would this cause the same symptoms that you just described?

Fred

 

Fred, it is unlikely as long as you did not remove the fluid from the MC.

Double check your work.

1. Double check all fittings for integrity; fix and tighten as needed, 2. Purge the system by using either the bud-on-the-brake method or a power bleeder and the PROPER bleed procedure (check a shop manual for details), 3. Pump several bottles of fresh DOT3 through the system.

If the brakes worked well before , they should now.

I've done several brands of ABS and as long as there was not a problem with the ABS prior to the brake bleeding, an ABS system is no exceptional issue.

 

Will do.

Thank you.

 

We bled the ABS Module and calipers using the methods outlined in the Service Manual. Before that, I also sucked two big bottles of fluid through the system w/ a Mighty Vac.

The brakes held overnight, and we thought they were good to go. I reinstalled the wheels/tires, and took it out for a spin. In the time it took me to get them back on (and I took a couple hours to do it... I was doing other stuff @ the same time, eating, etc) the brakes faded again and they were gone.

I had a buddy bring a Tech 2 tester from the dealership he works at to test, and the system wasn't throwing any codes at all. AFIAK, the only thing that we haven't bled is the Master Cylinder.

I'm stumped, and so's my buddy who's the lead mechanic @ said dealership. When I rebuilt them, I took a brake hone to the inside of the caliper cylinders, but that was to just knock off a little of the powder coating. They went back together fine; no left over pieces I don't see any fluid leaking under the car... What to try now?

Fred

 

Holy ****!!!....I have/had this same problem. But, I put it off for now and ripped the whole car apart for a forged buildup and figured I would worry about it when its back together.

Anyhow, last september I decided to paint the calipers. Well, i removed the front ones from the lines painted them, reinstalled them and went onto the back. The backs I did not remove from whole assembly due to not wanting to rip apart the ebrake setup, but did disconnect the lines so I had more slack to work with. painted them put them back on. Then spent the rest of the day bleeding the brakes(using my gf to pump the brake, but the car was off the whole time...didnt know about the running car abs stuff). ran a bottle or so through the system. Did all the brakes at least 2 times.

After that, I said let me feel the pedal...it was as stiff/firm(with the car off) as it has ever been. I figured awesome, put the wheels on cleaned up went to take it for a spin. Started the car, put it in reverse, backed up then went to hit the brakes and my foot went to the floor and I nearly hit the telephone pole behind me when it didnt stop. I just let the clutch out and let it jerk to a stop

So, I park it.....we bleed the whole system again. It feels stiff. This time I start the car intantly. As soon as the car turned on....it lost all stiffness and went right to the floor with no effort at all. Bled it again....start it, no brakes. It seems as soon as the vaccum is in effect it looses all brakes...WTF!!!

That was 2 days before I ordered my shortblock and many other parts and was getting ready to do my buildup. So, I parked the POS in the garage and considered it dead....and started ripping it apart that weekend. I have yet to get it back together and running with the new motor/nitrous kit and deal with that problem, but will be shortly. Im going to try all that has been posted here also when its back together. I didnt do it with the car running so that might be my problem. I guess im used to my old cars with no ABS. I was going to blame it on the MC also, but it worked perfectly before I took the calipers off....so it has to be air somehow that I am not getting.

 

N2OpwrdTA, it's like you summed up my whole problem in one post. Fortunately, when I've tried to drive it, I've got just enough E-brake to keep from hitting anything.

When I hit the brakes hard, it goes almost to the floor. Then it 'hits' something and if I press harder, it'll go past that 'something' and stop me somewhat. Well, I haven't tried stopping from anything more than 10mph or so...

Fred

 

It sounds like you have a real stumper.

But you mentioned the two areas of concern, the MC and the calipers that you honed. You maybe getting air into the system if the honing was enough to throw off the tolerances. While there may be a problem like air in the system or worn parts in the MC, I am concerned about the honing part. If you did much honing then you may need to replace the rubber seal.

One last thought. I may be mistaken but I believe it is possible to install the calipers upside down. If they (the fluid nipples) are upside down you will have a very hard time purging the air out not ot mention other problems. Are your calipers on correctly. I trust they were not reversed.

 

I didn't do but maybe 15 seconds of honing on each one, and the honer had tired springs on it. ... though enough to break the integrity of the chamber might've done it. It was mainly to knock paint off done by the careless powdercoater. I also didn't put any of the seals back in until after I worked 'em over a little.

I don't believe that I installed the brakes upside down, but here's the kicker. When I pulled the front ones off, the left was marked w/ a R and the one on the right was marked w/ a L. Backwards. That's the way I put them back. I'd forgotten about that until you mentioned it. The bleeder valves are near the top of each one, and I'd think that's how you would want them to be, but at this point, I'm just about willing to try anything. Voodoo... Exorcism...