911vet

I think I zapped my master cylinder. It was one of those blury-eyed 2am things... after using the pressure bleeder to replace my brake fluid, I followed the Bentley Manual instead of my own common sense, and did a final pedal pump bleed of the brake lines.

Now the pedal feels squishy.

I have new lines, new pads, new ATE fluid, old rotors.

Pedal feels worse than before the new lines, pads, and the bleed.
Did I ruin my Master Cylinder? Any way to check it?

I've read the tech article on Pelican and I'm trying to figure out how big this job is. How much time? How much frustration?!

Thanks

deep_uv

Bleed it again with the pressure bleeder first before you do anything. No need to do a pedal pump. You likely introduced air in the lines doing that, IMHO. Get another can of fluid and try again.

old man neri

Shannon, you're the only person I know who would be bleeding their brakes at 2am.

I have heard that knocking the individual callipers with a mallet sometimes helps dislodge air bubbles free. I would not jump to the assumption that you have killed your master cylinder. You could also try a different colour of ATE fluid, I think they make both a gold and a blue. It would help in making sure it is fully flushed. Just a thought.

-matt

KC911

I agree with the others that you may have simply introduced air into the system with the pedal bleed. FWIW (although I have 930 calipers), I use the pressure bleeder to flush/bleed, and even though I bleed each caliper twice for good measure (two bleeders per caliper), one time seems sufficient as I never even see bubbles on the second pass, and my brake are, shall we say "good" . If by chance you did damage the m/c seals, I replaced my m/c with the 930 "upgrade", and that's not a big deal either. Hope this helps...

Keith
'88 CE coupe

911vet

OK, thanks everyone. You've made me feel better.
I have ATE Blue left over, so I'll rebleed the system and see how it feels.

That's what happens when you have no life except for a dog and a car.

MDL

Did you follow the instructions and put brake fluid in the power bleeder as they recommend? If not you are sure to have air in the system. Some will tell you that it's not necessary to bleed with fluid in the power bleeder but they are wrong.

911vet

I did put fluid in the bleeder.

First, I drained the car's fluid reservoir with a syringe to get all the crud out. I filled the pressure bleeder with fluid and kept the vent hose open on the reservoir until new fluid filled it. Then I closed off the vent hose.

Then I started the pressure bleed. Drained each brake until blue came through and then some. I used a LOT of fluid to be sure the system was completely flushed.

I also flushed the clutch (which had me swimming in fluid - yuk).

I did the brakes in the wrong order. Not sure that would really make a difference?

MDL

Bleeding in the wrong order would make a difference. You should bleed the RR and the LR- RF LF. I never bled my clutch before so I can't say if that is causing a problem. You are not supposed to peddle pump your brakes when using the power bleeder. It sounds like you just filled your system with air. If I remember correctly, the instruction are printed on the power bleeder. Is this the one your using?

http://www.motiveproducts.com/

KC911

Respectfully, but it is your advice above that is wrong. I (and many others) use the Motive "dry" with excellent results. I've done it both ways and prefer to use mine dry...YMMV.

Keith
'88 CE coupe

911vet

I followed the directions (at least I think I did!). It says to put fluid in the pressure bleeder rather than a "dry flush."

I flushed 500ml from each caliper and then did the clutch. I used over 2L doing the project, so I'm confident I flushed completely. Maybe I introduced air by doing the pedal bleed at the end? Or by doing the bleeds in the wrong order?

I'll redo the bleed as soon as another liter of ATE arrives from Pelican.

MDL

Keith, I tried to use mine dry the first time. I have read here that others have used it dry with success. I was unsuccessful until I did it the way the manufacture recommended it to be used. Pete and Steve straighten me out!

KC911

With all due respect to you, Pete, and Steve, I (and MANY others) will continue to use our's "dry" . It's a personal thing, but for you to say that one is "sure to have air in the system" if you use the Motive "dry" is simply false since a lot of us use the Motives in that fashion with excellent results. I'm not bleeding brakes all the time, and I just find it easier, with no cleanup mess, to simply add more fluid to the reseviour a couple of times while going around my car (9 bleeders X 2) and ensuring that the fluid never gets too low (i.e. as that would indeed allow air into the system), and that technique has been pretty bulletproof for me.

Keith
'88 CE coupe

MDL

Shannon,

I think between pumping the pedal and bleading in the wrong order is what is causing your trouble. I doubt you hurt the M/C.

MDL

Keith,

If it works for you and others, that's great! For me, I would rather use it the way the manufacture suggests and not have to keep removing the cap and adding fluid every few minutes.

Dan.

911vet

I don't know if you're right, but you sure make me feel better Thanks.