E53 - Brake bleeding issues

[FourPointEight-is]

Hello,

My X5 4.8is suffered from the "vacuum pump seal failure, oil in brake booster leading to brake booster failure" issue - I changed the booster with a new unit and re-used my Master cylinder. I got everything back together and no matter how much I bleed it (I'd have bled the system 3-4 times over 4-5 days) I can NOT get the pedal to firm up. It feels very, very soft. I do not have a pressure bleeder, so I am using the pedal to the floor method. Here's what I do:

I have used ISTA-D and done the bleeding with the ABS block as well by cycling the pump - still no go. Pedal soft as hell, goes all the way to the floor.

- Ask my helper to press pedal 5 times
- On the 6th time, hold the pedal to the floor
- Run the "ABS Bleed" procedure in ISTA-D
- I crack the bleed screw (1/4 turn or so) with clear tubing attached to nipple
- Close the bleeder screw
- Ask my helper to release pedal

I repeated this multiple times per corner until no dirty fluid nor bubbles were coming out. I bled in this pattern: Rear Right, Rear Left, Front Right, Front Left.

After doing all this I had absolutely NO firmness return to the pedal; So I thought I wrecked the master cylinder and got a new one and changed it out. After bleeding, there is still NO CHANGE in the pedal feel.

I am out of ideas at this point - I don't believe I have a fluid leak since I'm not losing any fluid (level stable). I am using DOT4 fluid.

The car is parked on flat ground. I have read that jacking up the rear may help but I can't see this helping - the highest point on the master cyl when the car sits flat is the rear port, so any air should be getting pushed out of that?

Never done this before - am I doing something wrong here or is something else broken? Car was FINE before I started this (with the exception of a broken brake booster making the pedal super hard).

[AlanGunn]

I have just found this post on a uk forum(xdrivers) and this is a quote from it.
"well had a good conversation with a newly opened indy to me (hes just resently parted from main dealer after 9 years and is 40miles closer than where i was going and 3miles from my work ) he said hes 99% (seen 5 x5s sent to him the same as mine) sure that what weve done is forced the seals on the master cylinder inside out from bleeding the brakes by pressing the pedal to the floor 100s of times, so ive ordered a new master cylinder (£55 motor fators) and he said to fit this and then bleed from the beging with the pressure bleeder which will take a fair bit of time! anyway today they have got alot worse with use but the fluid level is exactly the same so no leaks, he said that when the seals have been poped just the front calipers work. However when i asked to book it in with him he said it was a simple job for my bro who did all the new brake pipes and in his explanation he never menchioned anything about laptop for abs unit, last time we bled it running so the abs etc was powered up! also there is no abs brake function on inpa and it has everything else. i could be wrong and my brother is going to phone him when he does it. oh well get the e46 out for some fun!"
Link to the full post.
brake bleeding

[Purplefade]

I went through the same thing, it wasn't until I finally sprang for a pressure bleeder that I was able to get the job done. I think it's the servos in the ABS block that just don't like the pressure being taken off of them while bleeding.

I, as you did, bled mine a half dozen times with a partner and never for pedal - 15 minutes later, with the pressure bleeder... pedal was awesome and I was done.

If you can barrow a pressure bleeder definitely give it a try, I've never seen the "press and hold" method work on an X.

Good luck!


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[FourPointEight-is]

I have a pressure bleeder on order... will give you guys an update once I get it.

I have spoken to a lot of people and there is a ton of conflicting information. I've got people swearing on a stack of bibles that they managed to get E46 cars bled by just stomping the pedal and not bothering with cycling the ABS pump at all.. others claiming it can't be done without the software to cycle the abs pump.

Who woulda thought something so simple would take so long?

[Purplefade]

Originally Posted by FourPointEight-is

I have a pressure bleeder on order... will give you guys an update once I get it.

I have spoken to a lot of people and there is a ton of conflicting information. I've got people swearing on a stack of bibles that they managed to get E46 cars bled by just stomping the pedal and not bothering with cycling the ABS pump at all.. others claiming it can't be done without the software to cycle the abs pump.

Who woulda thought something so simple would take so long?

Heard that - you will get there, I've been through it as well.

I can say all I did was open the ABS block and bleed, I never cycled the pump and I had no issues.

You will be amazed with the difference in using the pressure bleeder the pedal should come right up for you.

Keep us posted


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[andrewwynn]

The "stack of Bibles" folk just never had air where it's not supposed to be. As long as air is only in the lines downstream of the abs of course you can use the buddy system for bleeding. Brakes don't circulate the fluid there is only one line to each wheel so the fluid probably goes a couple inches back and forth under normal use.

I bought a pressure bleeder for the eventual swap of fluid. Turns out I'll need it for replacing my rear brake lines first. Glad I already had it on hand though.

[FourPointEight-is]

My pressure bleeder finally arrived - it's a Schwaben Compact bleeder.

I spent a couple of hours on it, had some issues with the bleeder as first it wouldn't seal properly around the reservoir (which I resolved with some teflon thread tape) and then it also seems to leak around the fitting which has the gauge on it (but this is a problem for another day).

Anyway I have made significant progress now. A ton of air came out of the rear right and front left calipers, it was very very frothy. I bled probably 2 liters of fluid through the system.

The pedal is a LOT harder but still not quite where it was before all this mess started. Obviously I need to bleed it a bit more which I will do later this week and report back. But it's looking good thus far.

[andrewwynn]

If air got in the ABS block or the pre-charge pump, you need the right tool to engage then to finish bleeding. There should be a big rubber disk to seal the air over the reservoir and for the other side thread tape should resolve. I seemed to have lucked out and no air got in when. I replaced both rear lines but there seems to be a tiny bit of air in the lines I can feel a bit of compression nothing I can't life with until I do a full exhange of fluid that is already planned.

[FourPointEight-is]

What is the "right tool to engage them to finish bleeding"? I have used ISTA-D to do this so far, and I pressurize the system from the reservoir cap to 20 PSI using my Schwaben "compact bleeder"

Anyway - I have bled 3 times now with my pressure bleeder. Very little air is coming out and there is absolutely NO improvement. Pedal is somewhat hard with car off, but with car on pedal is absolute mush.

Say pedal at its rest position is 1, and pedal at the floor is 10,
I have NO BRAKES between position 1 and 8
Position 8.5 I have some braking
9.5 Brakes are locking solid - enough to activate ABS.

Where to next? Really looking forward to getting this fixed. Car IS drivable at this point, but the first 85% of the brake pedal travel doing NOTHING isn't exactly confidence inspiring!

[andrewwynn]

The way you describe the pedal drop is already exactly what it feels like when one front back circuit is open to the atmosphere. You said that you let the air out with your NT510 or equivalent?

If you aren’t spraying fluid out the front or back circuit the air must be in the pre-charge pump or the ABS block


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