540i bleeding problem

[jmmcalpin]

I replaced the rear disc pads and the peddle was a little soft so I bled the brakes manually and while I was bleeding them fluid stopped coming out of the bleeder screw.
I finished all four wheels and now when I break it pulls to the right, if feels like I am not getting hydraulic pressure to the left 2 calipers..
I did not use the ABS diagnostic tool but I also do not think I have gotten any air in the system..
Any help appreciated.
2000 540i manual transmission
John

[bmwdirtracer]

Welcome to the forum, John.

How much experience do you have?
You know that new pads are always "soft" until they're properly bedded?
What method are you using to bleed? Pressure bleeder? Vacuum Bleeder? A second person pumping the pedal? "While I was bleeding fluid stopped coming out" kind of makes it sound like you just opened the bleed screws and let them drip.
There's fluid in the reservoir?
Have you replaced the rotors?
Rotated the caliper 360 degrees and kinked a hose?

[jmmcalpin]

Chris thanks for the help, I am a pretty experienced home mechanic working on cars since the 70s, Yes I am that old...
I bled them with my son on the brake pedal while I opened and closed the bleeder nut with a hose on it ending in a container of brake fluid, I don't think I got any air in the line and I kept the master cylinder reservoir full.
I did not replace the rotors when I changed the pads, it was the rear rotors and they were in good shape, I don't mind replacing them now but obviously that is not why I am not getting hydraulic fluid to the calipers.
I checked for kinked brake hose lines, they look fine, no tension on them at all. and calipers are in right.
When I was bleeding them I opened the bleeder screw and got fluid twice when my son pressed on the brakes but the third time I did not get anything. I closed the bleeder screws and went on to the driver side rear , then passenger front and drivers front.. I believe 2 of the calipers had the same condition, got 2 cycles of fluid coming out then nothing..
I can see rust on the passenger rear rotor looking like the pad is not engaging the rotor , the other 3 look nice and shiny.
I tried cycling the ABS on a gravel road and got them to make the vibrating cycling noise but the right 2 tires did not make a skid mark while the left 2 did.
It appears something is blocking the hydraullic fluid from going to the 2 passenger calipers..
By the way, after cycling the ABS on the gravel the pedal firmed up and is in excellent shape, before that the pedal was going to the floor before braking but now I only go about an inch before the brakes stop the car, but as I said it pulls very hard to the left. Again as if the left 2 brakes are working and the right 2 are not.

Is there possibly a check valve in the system that when it sensed no pressure on the rear brake it closed off the hydraulic to that caliper thinking I had a broken brake line ? and just needs to be reset?
I think I did have the car key turned to on so the ABS was on while i was bleeding the brakes..

Thanks for any ideas or help.

John

[bmwdirtracer]

Thanks for the clarification, John. I'm much more confident now that we're not likely dealing with operator error. That said, I'd not leave the ignition on during bleeding in future.

I think I'd start by using a sewing needle to poke the right rear bleed screw while it's open. If you still get nothing, remove the screw and poke the hole in the caliper with that needle. (then have your son push the brake). Repeat at the front right.

If this does not work, unscrew the joint between the hard steel brake line and the rubber brake line at the front right, and see if you can force fluid out there. If so, replace the rubber brake hose(s). (Good time to buy a complete set of stainless lines)

I suggested the front right on this latter, because the rear has 2 rubber hoses each corner, not just one.

[jmmcalpin]

Thanks Chris I took the bleeder screw out and it is clear. I poked into the caliper through the bleeder hole and it seemed dry. I pressed on the brake with the bleeder screw out and got nothing, this is all on the passenger rear caliper, I did not have time to take the rubber hose off the steel line yet but I suspect it is up at the ABS or Master cyclinder.

I did take the passenger rear caliper off today and everything looks correct. I then tried to push the caliper back into the flat position and could not get it to move. When I replaced the pads a few months ago this procedure worked fine and pushed fluid back up into the reservoir. I tried to push the brake with the caliper off (pads on and a wrench the size of the rotor) and was not able to move the caliper out.. So basically the caliper will not move in or out. It could be a frozen caliper but strange that it happened when I bled the brakes. And I believe if I were to do it on the front caliper I would get the same result..
I believe I have a hydraulic lock somewhere in the system.. Could the ABS or DCS lock out the brakes due to bleeding them with the key on? Is there some safe way to reset the ABS/DCS?
As I said previously I did skid on gravel and the ABS sounded like it was working but only the driver side tires left a mark in the gravel.

- - - Updated - - -

Thanks Chris I took the bleeder screw out and it is clear. I poked into the caliper through the bleeder hole and it seemed dry. I pressed on the brake with the bleeder screw out and got nothing, this is all on the passenger rear caliper, I did not have time to take the rubber hose off the steel line yet but I suspect it is up at the ABS or Master cyclinder.

I did take the passenger rear caliper off today and everything looks correct. I then tried to push the caliper back into the flat position and could not get it to move. When I replaced the pads a few months ago this procedure worked fine and pushed fluid back up into the reservoir. I tried to push the brake with the caliper off (pads on and a wrench the size of the rotor) and was not able to move the caliper out.. So basically the caliper will not move in or out. It could be a frozen caliper but strange that it happened when I bled the brakes. And I believe if I were to do it on the front caliper I would get the same result..
I believe I have a hydraulic lock somewhere in the system.. Could the ABS or DCS lock out the brakes due to bleeding them with the key on? Is there some safe way to reset the ABS/DCS?
As I said previously I did skid on gravel and the ABS sounded like it was working but only the driver side tires left a mark in the gravel.

[bmwdirtracer]

I highly recommend that you unscrew the inboard end of the front right brake hose, and see if you can make fluid come out there. 11mm line wrench and 14mm wrench or sometimes, 11mm line wrench and 17mm wrench.

[jmmcalpin]

Ok, I will try that next...

[jmmcalpin]

Chris , I pressed on the brake with the front passenger tire off the ground and the tire kept spinning, both the front and rear passenger calipers are not receiving the hydraulic pressure from the ABS. I then took the bleeder screw out of the front passenger caliper pressed the brake and nothing came out, the bleeder screw was clear and there was fluid on the bottom of the screw.
Next I took the metal brake line off the bracket where it attaches the the rubber hose and fluid flowed out of the caliper screw opening so I put it back in place, I then pressed the brake with the metal brake line separated and no fluid came out, there was fluid present but again no pressure..
I guess it is the ABS or Master cylinder, any next ideas?
John

[bmwdirtracer]

Wow, I am surprised. But diagnostics continue.

Now, go unscrew the steel brake lines from the master cylinder. You can just make them loose enough to spray fluid; maybe two turns. Then (after making sure the reservoir has plenty of fluid), have someone press the pedal.

The master cylinder does not split from left to right; neither does the ABS.

You might need to go out and activate ABS hard again, then come back and bleed again.

Do you have an ABS warning light? Any codes in the ABS/DSC?

[jmmcalpin]

Ok I will try that tomorrow, I looked at it today and there are 2 braked lines coming out at the base of the master cylinder and one at the far end, then a few return lines. I assume you are talking about the 2 coming out at the base, they are marked 25V and 30 (H maybe), the one in the front and the return go to a round unit toward the front of the car and it looks like the 2 from the base go to the ABS , I would guess.
No warning lights or codes , I can plug in the ODB II and see if I read anything but the engine warning light is not on.
John

[bmwdirtracer]

The ABS module has its own codes, which need to be read at the 20 pin round diagnostic port underhood, using a good BMW specific diagnostic scanner.

[jmmcalpin]

How expensive is a good bmw diagnostic scanner, do you have a recommendation which one and does it do the "ABS cycling function you do when bleeding the brakes" , might be worth it.

[jmmcalpin]

ok Chris, I partially opened the 2 metal brake lines to the master cylinder and they both blasted fluid when I pressed on the brake, I then went to the driver rear caliper and bled it, some fluid came out but after pressing the peddle a few times it stopped coming out. I tried the passenger rear caliper and still didn't get any fluid. So I think I have pressure going to the ABS but nothing coming out. I could take the brake lines off the ABS input and out put to verify that but I am pretty sure I am going to need to run the diagnostic tool on the ABS to cycle the solenoids. Do you know if there is anything else in between the master cylinder and the ABS?

John

[bmwdirtracer]

Hi John,
Personally, I don't think I ever had to use the DIS bleeding of the ABS unit, although I recall actually doing so once or twice, well over a decade ago, when I thought it was necessary.

That said, I always use a pressure bleeder and a vacuum bleeder, and the ignition is never on. I have replaced quite a few ABS units, complete, without ever doing computer-aided bleeding. I do not use manual pumping either though, except on ancient cars, or in emergency.

In lieu of being able to talk to the ABS module:
It seems to me that if you bleed the system without power to the ABS, the hydraulic braking circuits will be open to all wheels, by design.

That said, I'd certainly want to have a conversation with the ABS/DSC. And then I'd head down the street, slam my foot on the brakes hard enough to stop the earth, and see what codes I get in the ABS....or what behavior I get on the ground. Hell, do it a few times, and see if everything just fixes itself!

The ABS computer should have codes, or the issue won't be in the ABS.

[jmmcalpin]

Ok, for some reason I have not been able to bleed the brakes with the foot on the pedal method, I simply do not get pressure past the ABS unit, that said, I have not tried a pressure or vacuum bleeder so I guess I could try that.. I did try pressing the brake on hard enough to engage the ABS and the right tires dont respond. no sign of stopping in the gravel, which makes sense since no hydraulic pressure is getting to them.
i am going to have European Performance do a full bleeding and use the computer as per the manual and see what happens.
Thanks for all your help, I will let you know what they find.
I may have screwed something up the first time I bled them and this will hopefully recover that.
If I have time I may pick up a pressure bleeder and try that myself but doubt it will help at this point.
JOhn

[jmmcalpin]

One other point , I noticed I have DCS with the pre charge pump it that helps with the discussion, it does not look like it is directly inline with the brake lines so I assume that has no effect on this problem.

[bmwdirtracer]

John, neither you nor I can do much with the ABS/DSC, without using a computer. Do your ABS and traction lights (triangle in circle) come on when you start the car, and then go off? I just keep thinking that this issue doesn't feel like an ABS (/DSC) problem to me. Again, I'd have had a serious conversation with the ABS via computer by now, anyway.


New thought: um, when you jacked up the car to do the brake bleed: Any chance you've kinked the steel lines with the jack? (I don't know how you could kink the LF, but we need to look at LF separately from LR, unless the ABS module says there's a reason they're misbehaving simultaneously. There is no hydraulic commonality between the two left side calipers that does not involve the right side brakes.)

How nasty WAS that brake fluid, when you bled it?

[jmmcalpin]

ok so had an indy do the computer diagnostic , the valves in the ABS are not working, they are blocking fluid flow to the calipers... it appears the fluid is rusty and my guess is when we bled the brakes we forced rust into the ABS and that is why we initially got fluid and then it stopped flowing.. the indy mechanic cannot get fluid flow so I need to replace the ABS/DSC hydraulic pump .. the new part is $3,700 , soooo do you have any ideas for a rebuilt pump, I found a number of used pumps on ebay for $200 and am going to buy one unless you have a better idea.
Also the indy suggests replacing the master cylinder, do you think that is necessary or do you think I could get all the rust out of it... obviously I don't want to force rust into the new ABS so I will flush out all the lines with a pressure bleeder.
one last question, I do see a precharge pump on the front driver fender, it has 2 lines to the master cyclinder, do I need to flush that and how do I do it. I also have one line leading to the clutch pedal (I believe ) do I have to flush that.

Thanks for all your help, I kinda knew it was the ABS blocking the fluid from the beginning but I like the way you stepped me through confirming it.

John

[bmwdirtracer]

http://www.autoanything.com/brakes/p...ke-bleeder-kit

If you have the time to try one more thing, I have one of these Phoenix reverse bleeders. I'll lend it to you if you want to try it. No promises, but maybe, just maybe it'll squirt your rust out the way it came in. The kit is at work, I can't mail it 'til Tuesday. I rarely use it, so I'm fine without it for a week or so.

If you want to borrow it, PM me with your address. I've got a feeling I can trust you.

Chris

[jmmcalpin]

I would really appreciate borrowing it, I sent you a PM , let me know if you don't get it.. thanks again

[bmwdirtracer]

I have received 2 PMs today, but none from you. Do you have any PM's stored, either sent or received? When you're new to the forum, the quantity is severely limited...like ONE, for the first dozen posts or so. (Delete all your PMs)

I'll send YOU a PM with my email address.

[jmmcalpin]

Ok, I just sent you another message, lets see if that one goes. If not I will send it from my other email account , I do have one stored message which must be the first one I sent you but I can't find it in any folders or figure out how to resend it.
Thanks John

[bmwdirtracer]

I got it, John. I'll mail the Phoenix tomorrow, unless I don't make it to work because my back is twisted in painful knots right now.

[jmmcalpin]

Thanks Chris, Hope your back is better , nothing worse than back pain

[jmmcalpin]

so the final outcome was I pushed rust into the ABS hydraulic unit and had to replace it, I used Chris' reverse bleeder to get the rust out of the system before putting a used ABS hydraulic unit in and it fixed the problem, thanks for all the help Chris.