Brakes question

"PartyPooper2012" (PartyPooper2012) 09/30/2019 at 07:44 • Filed to: None

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Hey all. I have an ‘05 Mini Cooper S with questionable brakes.

Replaced master cylinder. Bled it till I can’t bleed it anymore. Pedal gets hard when car is off. When car is running, pedal goes down to the floor.

After reading some more, it seemed maybe I had air in ABS pump. Bought a Foxwell OBD2 gizmo that lets me activate the ABS pump, however, I am not sure what all it’s doing. There is no option for autobleed. just to operate ABS pump etc. I did that several times. ABS pump whirs and makes noises, but pedal is still going down to the floor.

!!! UNKNOWN CONTENT TYPE !!!

Are there any other places where air might be getting I have not checked yet?

I don’t want to take the car to a dealer. it would be 1000-1500 which would basically be the value of the entire car.

Did I buy wrong tool? Do I need some other shit that would bleed my ABS pump?

What am I missing with ABS pump? 

pip bip - choose Corrour > PartyPooper2012 09/30/2019 at 07:59

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brake booster ok?

I like cars: Jim Spanfeller is one ugly motherfucker > PartyPooper2012 09/30/2019 at 08:01

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Hm. Did you follow a normal bleed procedure while operating the ABS pump? Or did you just cycle the pump? If you just cycle the pump, air would move out of the ABS pump but then right back into it. There may be a bleeder valve on the pump itself, too. Do you have a service manual?

diplodicus forgot his password > PartyPooper2012 09/30/2019 at 08:04

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Did you bleed again after cycling the abs pump?

Did you read this already? https://www.pelicanparts.com/techarticles/MINI/31-BRAKES-Bleeding_Brakes/31-BRAKES-Bleeding_Brakes.htm

Victorinoo > PartyPooper2012 09/30/2019 at 08:06

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I have suffered similar issues with abs cars. No amount of regular bleeding was able to get the air out. I can’t chime in on bmw/mini specifically, but I have heard that you have to use a pressure bleeder on ABS cars to get all of the air out.

MKULTRA1982(ConCrustyBrick) > PartyPooper2012 09/30/2019 at 08:09

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Simplify, add lightness and reduce complexity by removing the ABS wizard entirely?

Kidding aside others are on the right track with more research I think. Best of luck bleeding brakes sucks 

PartyPooper2012 > I like cars: Jim Spanfeller is one ugly motherfucker 09/30/2019 at 08:19

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I don’t have service manual. I tried normal bleeding procedures before activating pump with bleeder closed and then with bleeder open. No liquids came out with bleeder open so I am not sure if pump was pumping liquids through it. 

GoodIdeaAtTheTime > PartyPooper2012 09/30/2019 at 08:19

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Pressure bleeder while cycling the abs pump. Don’t use to much pressure or the reservoir will explode. I learn from experience :) its the o nly way I have ever gotten all the air out of the system on the early Mini s.

PartyPooper2012 > diplodicus forgot his password 09/30/2019 at 08:26

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I did. No dice. 

PartyPooper2012 > GoodIdeaAtTheTime 09/30/2019 at 08:28

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OK so how did you do it? Pressurize system gently. cycle the ABS pump WITH bleeder valve on caliper open or closed?

This seems plausible but I didn’t have pressure bleeder so I was trying to add pressure by stepping on brake pedal. Didn’t feel good - pedal was vibrating and  i was afraid of breaking things. 

pip bip - choose Corrour > PartyPooper2012 09/30/2019 at 08:31

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new brake fluid used was of an equivalent  quality or better than BMW/MINI state to use?

PartyPooper2012 > pip bip - choose Corrour 09/30/2019 at 08:33

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probably. Since the car was not running, liquid was of ambient temperature so it was not boiling. Any liquid should have worked but pedal still falls to the floor like a little biatch

PartyPooper2012 > pip bip - choose Corrour 09/30/2019 at 08:34

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if brake booster was malfunctioning, it would be hard to press the pedal. I have the opposite. 

pip bip - choose Corrour > PartyPooper2012 09/30/2019 at 08:36

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buggers that theor y then

PartyPooper2012 > GoodIdeaAtTheTime 09/30/2019 at 08:37

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Also - what the hell is the pump doing when it’s activated - shouldn’t it force liquids out?

I had a clear line hooked up to front left caliper - activated ABS pump with bleeder open and no liquids came out. Only thing I can think of is that maybe the pressure is needed for this. But without pressure, would ABS pump force some liquid out? is it a pump or a noise maker? 

PartyPooper2012 > pip bip - choose Corrour 09/30/2019 at 08:39

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This is why I am checking live automotive encyclopedia (AKA Oppomunity) to see if I am missing something super obvious. Just ordered a pressure bleeder. Will try that before I push the car off a cliff. 

Fuckkinja > PartyPooper2012 09/30/2019 at 09:00

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I ran into the same problem last week on my Caddy. Finally gave up and paid an indie shop $70 to bleed abs. 

Victorinoo > Fuckkinja 09/30/2019 at 09:03

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Do you know if they used a pressure bleeder? Just curious 

PartyPooper2012 > GoodIdeaAtTheTime 09/30/2019 at 09:36

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I read to see how ABS pump work and what it does - it doesn’t necessarily force liquid out of the system. It just creates more space for liquid to go to and releave pressure.

The question is - if ABS is not active and brake lines have been bled, the air in ABS pump should not matter? It should go around it and work normally. If I drive and activate the ABS, then i introduce air back in the line and brake pedal get squishy again...

 I am still not convinced... 

I like cars: Jim Spanfeller is one ugly motherfucker > PartyPooper2012 09/30/2019 at 09:42

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Hm. Fluid should have come out if you cycled the pump with the bleeder open. Weird. 

PartyPooper2012 > I like cars: Jim Spanfeller is one ugly motherfucker 09/30/2019 at 09:59

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Well, I did a bit more investigating this morning. While ABS pump is a pump, it doesn’t pump liquid out. It creates a cavity by moving a piston for a given wheel. Pressurized fluid goes into this cavity and releases pressure unlocking the brakes.

So bleeder valve closed or open doesn’t matter. No liquids will flow.

HOWEVER - if my ABS pump was not activated (but had air in it) when I bled the brakes the normal way without activating the pump - just good old push pedal, bleed caliper - wouldn’t the air be trapped in ABS pump and have no affect on regular brake pedal operation?

If I were driving and hit the brakes hard and locked up and activated ABS pump, it would open that air up again and cause issues... but I am not sure here.

Is abs plumbing exposed to regular braking lines or is it locked up with valves of sorts?

Dang black magic. 

Long_Voyager, Now With More Caravanny Goodness > PartyPooper2012 09/30/2019 at 10:09

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I’ve had a bad booster cause a squishy pedal before.....

PartyPooper2012 > Long_Voyager, Now With More Caravanny Goodness 09/30/2019 at 10:14

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how though? Brake booster gives my foot extra super powers to force the liquids. If it malfunctions and no longer boosts, my foot become a mere human foot unable to successfully push brake pedal. How would it make the pedal soft?

Long_Voyager, Now With More Caravanny Goodness > PartyPooper2012 09/30/2019 at 10:18

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Not sure, possibly “over boosting”?

I’ve had 2 bad boosters cause squishy brakes on vehicles. I replaced and rebled everything numerous times before saying screw it and replacing the booster. New booster, problem solved.

Not saying that’s the case here, just making you aware that I’ve had a bad booster cause issue.

PartyPooper2012 > Long_Voyager, Now With More Caravanny Goodness 09/30/2019 at 10:27

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I am not ruling it out. And I appreciate your chiming in with experience.

I just ordered a pressurizer. Gonna try bleeding it again while pressurized and activate the pump.

Watching this video - sure the accent is a bit thick but

Pretending the systems in bike and car and fairly similar - there seems to be an isolated area between dump valve and non return valve - if the air is trapped in this area and ABS is not active, it should stay isolated and regular brake bleeding should get rid of the air for regular brake application without abs . That was not happening with all the bleeding I did

I will try with pressurized system and abs pump on and see. If that fails, ill see what the brake booster will cost. I am tired of spending money on witchcraft. Off the cliff it goes

jimz > PartyPooper2012 09/30/2019 at 10:38

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did you bench bleed the MC before installing it? 

PartyPooper2012 > jimz 09/30/2019 at 10:42

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Sort of. Half assed. It did not come with any of the hosery but I did put some liquid through it. It may have leaked right out while i was installing it.

It was not a gracefull install

GoodIdeaAtTheTime > PartyPooper2012 09/30/2019 at 11:45

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Pressurize the brake system. Open the bleeder and activate the pump. Close the bleeder and turn the pump off. Repeat 3 times per bleeder. Though I did have one where I had to drive the car, put two wheels into the grass, and t hen slam on the brakes to activate the abs. Worked fine afterwards, it is an old Jaguar/Land Rover trick on cars with a mushy peddle. Crap builds up in the ABS valve block and traps air bubbles. The fluid flows around the air bubble, so you get fluid but not the air. Hydraulics are funny :/

Sorry about the late reply, I am hiking across God’s country right now and have a pretty spotty signal. First time in weeks I have a cell signal.

PartyPooper2012 > GoodIdeaAtTheTime 09/30/2019 at 11:49

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No worries. I am getting pressurized gizmo tomorrow so not doing anything till then.

If that doesn’t work - Oppo special. Highest bidder gets a fixer upper. 

Long_Voyager, Now With More Caravanny Goodness > PartyPooper2012 09/30/2019 at 12:29

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I think you’re probably on the right track in this case. Good luck

Fuckkinja > Victorinoo 09/30/2019 at 12:33

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They did not use a pressure bleeder. They just fired the abs. After it quit making noises. They bled it normally. I was standing right next to them.

You can’t try putting the vehicle up there n jack stands and putting it in drive. Jam the break pedal to fire the abs. 

I like cars: Jim Spanfeller is one ugly motherfucker > PartyPooper2012 09/30/2019 at 13:32

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Hm. If it’s not bleeding as it should, I would seriously consider finding a PDF of your factory service manual online (even if you have to pay for it) for the appropriate procedure.

Urambo Tauro > PartyPooper2012 10/05/2019 at 20:53

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So did you make any progress on this yet? I just found myself in a similar situation, working on a Buick. Pedal kinda stiff with key off, but straight to the floor with the key on. Could not for the life of me get it to bleed the remaining air out. I was s taring down the barrel of probably going to have to spend hundreds of dollars on a proper scan tool, or let a shop bleed it for me.

So I tried a couple of things first . With the car up on jack stands, I ran it, in gear, off of the ground, and hit the brakes to stop the wheels multiple times . Now here’s the sketchy part, and I only attempt e d it because I happen to live on a low-traffic gravel road: though the pedal was barely responsive, I carefully (ready to downshift and/or hit the parking brake if necessary) drove it for about half a mile and back, hitting the brakes several times on the loose gravel to work the ABS. Life was starting to return to the pedal, but frankly i t still felt like crap.

I bled it (no pressure bleeder, just an assistant in t he driver’s seat) one more time. S ure enough, a few bubbles coug hed up , and on the next test drive the brakes felt totally normal again. Good, firm, responsive, predictable pedal. Not sure if running it up on jackstands prior to re-bleeding was enough, or if driving on the gravel did the trick, but I think it’s done now . If there’s any air left in the system, it’ s probably only a bubble or two, hiding behind an ABS valve or something where I can’t feel it.

PartyPooper2012 > Urambo Tauro 10/14/2019 at 05:28

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Hey, I had to put the project on hold. Had to take Mrs PartyPooper on vacation.

I purchased a pressure bleeder and the scan tool that is letting me buzz the ABS pump (I Don’t know what it does when it buzzes it, but I hear buzzing sound)

From all I’ve read and I think I even replied with a video to one of the comments on this thread - there is a segment of a brake line where the air could get trapped and when ABS activates that portion of the line is accessible and re-introduces whatever air it has trapped in it back into the system.

My plan this week/weekend is to pressurize the system, open each corner at a time while activating ABS pump. In theory, it should open that segment of the line and push the air out through the bleeder.

If that doesn’t work, I have a mini cooper for sale. Low miles. needs little TLC

From what I understand, ABS pump activates pistons inside abs pump that allow brake fluid to enter and reduce hydraulic pressure to slipping wheel . When things return to normal, that piston pushes the fluid out back into the system. This happens a few times quickly and thus you feel vibrations in your pedal when ABS is moving the pistons back and forth. My understanding which of course could be wrong is that there is a section of a line controlled by a valve that is normally closed off so when you push pedal, fluid goes straight to caliper. When ABS is activated, valve opens and allows fluids into the reduce pressure area. I am making these terms up as I go along. I am sure there is an actual name for them. Anyway. Pressurizing the system and bleeding with ABS buzzing is my plan. 

Urambo Tauro > PartyPooper2012 10/14/2019 at 09:46

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Unless this ABS operates differently, yeah that’s my understanding of the theory too. I think you’ve got a good plan there.

PartyPooper2012 > Urambo Tauro 10/14/2019 at 09:54

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May the brake gods be with us on this journey