semi-urgent brake issue - no brakes after bleeding

[Christien]

I just finished bleeding the brakes with new ATE brake fluid, using the Motive power bleeder. I've done this countless times with no problem at all. I got in the car before putting the wheels back on to test, and I have NO brakes at all - the pedal goes all the way to the floor (well, close enough - I know you're not supposed to literally put it to the floor). What's more, I can't build up any pressure whatsoever with repeated pumping.

I did notice far more air bubbles than usual when bleeding, esp. from the right rear, but I went around twice and on the last pass it was fine - no more air bubbles. The only other weird symptom was on 2nd pass on the outer nipple of the front left caliper, the fluid came out much faster than usual.

I've got a track day tomorrow and no brakes! I need to fix this fast! Suggestions?

Thanks!

edit: forgot to mention, I pulled the suspension pan off the examine the master cyclinder, and it's dry as a bone. There's no fluid leaking from any caliper, either.

[Oh Haha]

I assume you mean there were no EXTERNAL leaks from the master cylinder?

Did you do anything at all with the pads? If not, then disregard those as a problem.

if you did, check to see that they have gone back into position next to the rotors.

If you have a buddy available, have them push the brake pedal while you check each corner for obvious leaks.

I know you say you don't have any leaks but the fluid has to go somewhere.

Lastly, go around and bleed them again. I would do it the old fashioned way, if you have a helper.

Good luck and let us know the results.

[VFR750]

Weird.

Since you've done this before, your technique sounds fine. Pedal should have been firm.

Could your master cylinder seals failed internally?

Hydraulic brakes are so simple: Push = no pressure = air or leak


Reconnect the Motive bleeder, and pump it up to 14-15 psi, and let it sit for a while. Should tell you if you have a leak, or some trapped bubbles if the pressure drops. Can you depress the pedal with the motive bleeder pressurized? It should be firm.

[Christien]

Well, obviously my brain is in neutral. I went around again and got tons of air out. Maybe it was trapped way down the line, so when I went around a 2nd time it wasn't coming out. But after doing just the rears for the 3rd time, I began to feel some pressure in the brake pedal. Finished the fronts and voila, normal pressure. Went around again a 4th time, just to be safe, and they fell normal. What a relief!

So what's puzzling me now is how all that air got in there in the first place. I've never had anywhere near that much air. (I bleed frequently because of track driving) Then I remembered that while I was setting everything up, the MC overflow hose sprang a leak and I had high pressure air and fluid squirting out (luckily nothing got on the paint). Could air have entered the system then? I don't understand how it could have - air and fluid was rushing out (using the MOtive wet) - how could air have entered the system then?

In any event, all's well that ends well. Time for a test drive!

Thanks for your help guys - much appreciated!

[James Brown]

I rember (or not) reading in the past of this happening to someone. They did not find anything wrong with the system and he did not have any brakes after bleedeing. No replys on what happened but I suspect it's in the Motive bleeder, maybe a slug of air got into the system while you were busy bleeding the wheel cylinders. only thing I can think of, glad it all worked out. Now, try not to think about it when going into turn one!!!

[Oh Haha]

Glad to hear you got it resolved.

have fun at the track day

[moneymanager]

Stick with gravity, chuck the bleeder.

[450knotOffice]

Nah, stick with the Motive power bleeder. It has always worked great for me. Just use diligence and be sure air never gets into the system via the bleeder itself.

[VFR750]

It sounds like you did answer the question of how.

If the overfill line springs a leak, you push the fluid out of the resevior. That is probably how the air got in there. It doesn't matter too much about why or how.

Once you sealed that leak, and flushed the lines again, you got the air out. Becuause you used the Motive bleeder to fix the problem, you can say a properly installed Motive Bleeder is not the fault, the overflow air leak was. First I've heard of this. I'll pay attention, in case do the same. Thanks!

Very happy to hear your track day, today was not ruined.

[Christien]

Yep, the motive definitely wasn't to blame, it was me. I've tried all the other methods and the motive beats them all, hands down. The problem hereis that the overflow tube was old and very brittle. It broke at the nipple to the reservoir. It really should've been changed a long time ago. Several times after removing vice grips from the end (used with electrical tape to plug the tube while bleeding) I've had to cut a small section off, because I was unable to get it to re-open. I used some extra fuel line and a hose clamp, and it's good as new. Better, probably. Much easier to plug now - just screwdriver shaft or a punch and another hose clamp.

Now if the track would just dry up so I could get to driving!!

[tonythetarga]

The overflow line shouldn't let air in the system. More likely the bleeder valve seat is the culprit. Think of how many times they have been loosened and tightened, maybe overtorqued and worn out. They might need replacing.

[Christien]

Woah! Talk about firm brakes! Obviously I didn't just fix the problem, but maybe got some extra air out!! I've never felt brakes like that in this car!

Bleeders aren't the problem - they were all replaced 2 years ago.

[GaryR]

Now that you have that settled I would suggest on your next flush get rid of that blue crap that stains everything it touches and put in some Motul 600 or 660. Much easier to see when it's dirty, higher wet and dry boiling points. If on a tight budget at least use the ATE Gold.. if no budget go with Castrol SRF...

[janz]

Nothing like the old fashioned way with 2 people. I did the same with the power bleeder and it worked great to get the old stuff out and new in but ended up with mushy feeling brakes. Did it the old fashioned way and got some air out and now have great firm pedal and braking. I don't think the power bleeder has anywhere near the force of the brake pedal pushing the master cylinder. After all you only pressure the reservoir 12-18 lbs of pressure because anymore you stand the chance of breaking the plastic reservoir. Not sure how much pressure is applied with the brake pedal/master cylinder but I can only imagine as I've seen people stand on the brake pedal and hydraulics can build unreal amounts of pressure. Anyways I use the power bleeder then go back and do it the old fashioned way to be sure.

[RWebb]

the blue dye helps ensure that old fluid was flushed out

you alternate Ate blue with Ate gold

[GaryR]

Originally Posted by RWebb

the blue dye helps ensure that old fluid was flushed out

you alternate Ate blue with Ate gold

Except that blue tint took me about 3 flushes before it was gone, and the reservoir is permanently tinted. I have no problem telling old fluid from new and I bleed/flush about 4 times per year. It's just not that good to begin with IMO. Better than standard but on the bottom end of the best fluids for track use.

[Christien]

What else is there for track use?

I saw Prestone dot 5 "racing" fluid with the same boiling temp (500 6F) but somehow I doubt it's as good.

Btw I've had awesome brakes all day!

[James Brown]

I think you need 5.1 brake fluid

[GaryR]

Originally Posted by Christien

What else is there for track use?

In descending order for track use, just MHO of course..
Best (for a semi-reasonable price) is Castrol SRF at about $37 per PT (can only buy QT size)
Motul RBF 660 is my next choice (and what I use), about $25 per PT
Motul RBF 600 at $18 a PT
AP 600 at about $18 PT
Brembo 600 at about $18 PT
AP 550 at $13 PT
ATE Gold at $12 per PT