01 530i Rear Brakes Locked Up

[BimmerMan95]

Hey Guy, I’ve got some sort of strange issue with my rear brakes binding up. The story is, I purchased this car as a project vehicle. The problem with it was, it needed a new clutch and the rear brakes binding up.

So far I’ve replaced the clutch and no issues, but the rear brakes have left me stumped. Since I’ve had the car the only way I get to release the rear brakes is by cracking one of rear bleeders open. When doing so, both rear calipers release. I’ve bleed the braking system many times with no luck. I have a Foxwell Scanner that allows me to activate the abs unit for bleeding, also a motive bleeder. I followed the exact procedure from the Bentley Manual. So far I’ve replaced the Calipers and put on a used Master Cylinder from a working vehicle and still the exact same problem. Any help would be greatly appreciated

[seagreen323i]

I would check for a pinched hardline. Maybe the pressure of the pedal being pressed can overcome it but its acting as a check valve.

Sent from my SM-G973U using Tapatalk

[BimmrMeUpSnotty]

Well, sounds like it definitely is not the parking brake sticking, since you said once you crack the bleeders open, the calipers release. Did you bleed it enough? If the fluid was completely water logged, it will do that. But..... pop the hood open, look at the two rubber connecting lines on the firewall, coming from the ABS module. Those two lines are directly above the catalytic converters, they tend to dry rot early in life, if not maintained, they will dry rot enough to crack open, but I would expect fluid to leak out. But check them and all the brake hoses, I would swap them out with braided steel lines, the ones from FCP seem to be gone, but ECS has a cheap set, 6 lines, but if you get the Goodridge lines, more expensive, from Jolly Old England, they are good, always out of stock on back order, but those two lines that connect the ABS to the rear steel lines, they come covered with fiberglass insulation to protect them from all that heat, not to mention, probably keeps the brake fluid a bit cooler too. Stupid design on BMW’s engineers, I always blame all the usual faults on that idiot Chris Bangle..... I’d love to have five mins in a room with that dork, would only really need 30 seconds and finish the turd off for ruining the BMW marque. After checking the hoses, I would do full caliper rebuilds, the slid pins could be all goobered up, not alowing the calipers to slid smoothly, if the PO never addressed the brake fluid and allowed moisture to completely overcome the brake fluid, by the way, how nasty was the brake fluid? If it was dark , that is all you need to know, that is corrosion that built up inside the steel brake lines, the caliper pistons need to be inspected, they need to slide smoothly in the caliper, the rubber seals and boot need to be replace. When searching for which brand caliper rebuild kit to get, just get ATE, that is who made the brake calipers for our cars, the kits are cheap, just be careful not to rip the boot, you do that, moisture from driving in the rain will get in there and the piston will start to rust all over again.

[seagreen323i]

Size comparison

The Atlantic Ocean < Snottys hate for Chris Bangle

That hatred will keep this man alive forever.
Sent from my SM-G973U using Tapatalk

[BimmerMan95]

Yeah it’s definitely not the parking brakes, I’ve adjusted them temporarily back. I’ve inspected all the hard lines back to the ABS unit, and even the rubber lines mentioned. No pinched lines or leaks, could it be possible the ABS unit is causing this even without any codes? Maybe, something sticking on the inside of it? I’ve unplugged it while testing and same result. I’m fairly sure the lines are completely bleed, I’ve used almost a gallon of brake fluid during all this. Even done the two person method while bleeding.

[BimmrMeUpSnotty]

Screw him and the stupid designs he brings to this planet. That moron, why else would a former design chief at BMW fall off the radar after they fired his stupid ass, he claims that he left them, bs, they fired him. Why else would he disappear, fall off the radar, not have anything to do with cars, start a bs design studio in Italy, this was back in 2009, then the first opportunity comes, in this case, a stupid Chinese car company pitches him a project, and this is what the idiot and a half regurgitates out of his retarded ass....

- - - Updated - - -

Sorry for the Bangle rant, just saw your response. Open up the calipers, check all that out, then what Wagons Ho’s said on the master cylinder.

[seagreen323i]

I didn't instigate that lol

Let us know about the master. I remember reading you could use a master from another bmw model that gave you quicker brake response, if you are interested and have to replace it anyways might be worth a shot.



Edit: found it, not a straight swap but seems easy. E53 master cylinder.

https://r.tapatalk.com/shareLink/topic?url=https%3A%2F%2Fwww%2Ebimmerforums%2Ecom%2 Fforum%2Fshowthread%2Ephp%3Ft%3D2401466&share_tid=2401466&share_fid=1629&share_type=t&link_source=app

Sent from my SM-G973U using Tapatalk

[StephenVA]

Screw him and the stupid designs he brings to this planet. That moron, why else would a former design chief at BMW fall off the radar after they fired his stupid ass, he claims that he left them, bs, they fired him. Why else would he disappear, fall off the radar, not have anything to do with cars, start a bs design studio in Italy, this was back in 2009, then the first opportunity comes, in this case, a stupid Chinese car company pitches him a project, and this is what the idiot and a half regurgitates out of his retarded ass....

- - - Updated - - -

Sorry for the Bangle rant, just saw your response. Open up the calipers, check all that out, then what Wagons Ho’s said on the master cylinder.


Loved that "phone booth with a view" look of bad design influence. Good riddance to someone who got a position three levels of above his competence level.

On the brake issues. Something is energizing the brake fluid pressure. Only a few things can do that pedal pressure or the master/power booster. No water in the master cylinder body cavity?
Question: fronts ok and it is only the rear that is locking up?

[BimmerMan95]

Yes, only the rears are locking up. When I replaced the Master cylinder I didn’t fully remove the booster or check the cavity. I didn’t even think too, this time I will. I’ll order a new master cylinder as well. So it might be a couple days before I can give an update, but I will definitely keep you guys posted. Thank you all for all the info!

[philly98540]

Maybe the rear flex lines or one of the front ones is swollen closed on the ID of the hose? When you press the brake the line can expand enough on the ID to let the fluid through, then it closes back and traps the fluid in the caliper. Releasing it at the caliper bleed makes me think its not the caliper as it retracts OK once the fluid is released.

Old hoses do strange things. Maybe previous owners put crap lines or wrong fluid in there. Who knows.

I had an old Ford with unequal braking on the front and a draggy caliper. PO changed the hose on the left side, but left original on the right. Once I changed the hoses, all was good.

[ross1]

Maybe the rear flex lines or one of the front ones is swollen closed on the ID of the hose? When you press the brake the line can expand enough on the ID to let the fluid through, then it closes back and traps the fluid in the caliper. Releasing it at the caliper bleed makes me think its not the caliper as it retracts OK once the fluid is released.

Old hoses do strange things. Maybe previous owners put crap lines or wrong fluid in there. Who knows.

I had an old Ford with unequal braking on the front and a draggy caliper. PO changed the hose on the left side, but left original on the right. Once I changed the hoses, all was good.

THIS^
Just had this on an old Ferrari that had been standing for eons. Replaced the soft hoses and all is well.

[BimmrMeUpSnotty]

I never understand people that only replace one line, never even considering that the other line will be next if left alone. Bunch of rocket scientists.....

[StephenVA]

Collapsed rubber flex hoses would allow pressure to pass through on pedal activation but would hold some of it when released.
question after bleeding out excess pressure, the wheels turn freely, correct? When you walk up and press on the pedal, will they lock again? With or without the engine running?
replace the rear flex lines/hoses. Bleed out the system. If the problem goes away, cut open the old hoses length wise to expose the collapse internally. Most hoses display a dent externally when they are compromised and turn rock hard or total mush.

Note: lack of basic maintenance like flushing the brake fluid every other year will cause the calipers pistons to pit, seal failures, and the ABS block to fail. The calipers will lock up as soon as they get warm. This one thing when owning a BMW that you can count on.
Cooling systems is the other area that will take out a car with lack of maintenance. I run in to braggers frequently who pride themselves on their ability to never do anything on their cars other than drive them. Quote, "I never have to put money in this car!" Opening the hood is always like cracking open of a coffin. When a problem finally does occur, the car needs a large list of general preventive maintenance completed, to fix the little leak, noise, or drivability issue.

I will ill get off my tirade now....need breakfast.

[BimmerMan95]

I will see if I can get some lines locally before the master arrives. Visually I couldn’t see anything wrong with the flex lines. Yes, after bleeding excess pressure the wheels spin freely. It takes a few presses for the calipers to lock up. I’ve noticed with every press the calipers squeeze in tighter. Yes, doesn’t matter engine on or off, same result. I will double check one more time with the engine off, last few times I’ve done it was with engine on. I’ve been trying to do some research on the abs block, if something is sticking on the inside. Last attempt I had, I disconnected the abs unit before starting the car and it didn’t make a difference.

[BimmrMeUpSnotty]

Question, when you bled it, did you use a vacuum bleeder? Or did you old school it, someone pumping the pedal, holding and opening the bleed screw?

[BimmerMan95]

Both methods, recent was with a Vacuum Bleeder and a scan tool to activate abs bleed procedure.

[BimmrMeUpSnotty]

So you actually had someone pumping the brakes?
I don’t believe there is anything wrong with the master cylinder, it would lock up all corners if that was the issue. It is either the soft lines, or the abs pump. All the calipers probably should be opened up, it would not hurt to rebuild them anyway. But it will be the two lines connecting the rear lines, or the two lines to the calipers. Change it all out, do a full power bleed. Still doing it? Then there is something goofy with the abs pump.

[ross1]

Collapsed rubber flex hoses would allow pressure to pass through on pedal activation but would hold some of it when released.
question after bleeding out excess pressure, the wheels turn freely, correct? When you walk up and press on the pedal, will they lock again? With or without the engine running?
replace the rear flex lines/hoses. Bleed out the system. If the problem goes away, cut open the old hoses length wise to expose the collapse internally. Most hoses display a dent externally when they are compromised and turn rock hard or total mush.

Note: lack of basic maintenance like flushing the brake fluid every other year will cause the calipers pistons to pit, seal failures, and the ABS block to fail. The calipers will lock up as soon as they get warm. This one thing when owning a BMW that you can count on.
Cooling systems is the other area that will take out a car with lack of maintenance. I run in to braggers frequently who pride themselves on their ability to never do anything on their cars other than drive them. Quote, "I never have to put money in this car!" Opening the hood is always like cracking open of a coffin. When a problem finally does occur, the car needs a large list of general preventive maintenance completed, to fix the little leak, noise, or drivability issue.

I will ill get off my tirade now....need breakfast.

Are you channeling Snotty today?

[StephenVA]

Trying to. It must be all the ice in the driveway causing my brain freeze....

Sitting in the home office ordering shock and strut parts for the wagon, and looking at BMW events across the USA. Sad life I know.

[cnn]

For 2001 E39...the brake hoses are long overdue.
There are a total of six (6) hoses.

Not a difficult job if you follow this DIY I wrote some 10 years ago...

DIY: 1998 BMW 528i Brake Hydraulic System Overhaul (Brake Hoses, Caliper Seals/Dust Boots)
https://www.bimmerfest.com/threads/diy-1998-bmw-528i-brake-hydraulic-system-overhaul-6-hoses-caliper-seals-boots.538290/

- - - Updated - - -

One trick when working on brake system...
If you want to stop fluid from dripping, make a piece of wood long enough to wedge between the Steering Wheel and Brake Pedal. Measure distance such as it depresses the brake pedal ONLY 1/2 way down. Use a piece of towel to rpotect the SW.

Here is a pic from my 2006 X5 when I did the brake metal lines. This trick stopped the flow of brake fluid.

https://www.bimmerfest.com/threads/diy-2006-bmw-e53-x5-3-0i-brake-line-replacement.1350813/



https://www.bimmerfest.com/attachments/e53-brake-line-20-jpg.868219/

[BimmrMeUpSnotty]

I do the same thing, but just use a long prybar and wedge it between the pedal and the seat, just adjust the seat forward.

[StephenVA]

I use my dog

[BimmerMan95]

Well guys still same time result, new rear soft lines, new vacuum booster and master cylinder. Guess IÂ’ll be changing the abs pump next.

[StephenVA]

PM sent

[philly98540]

You do the front flex lines too? The ones in the engine bay.

[ross1]

Well guys still same time result, new rear soft lines, new vacuum booster and master cylinder. Guess IÂ’ll be changing the abs pump next.
Before you do that $$ project be damn sure there is no restriction elsewhere and no problems with calipers and hardware.
those don't very often go bad

[BimmrMeUpSnotty]

Man, might also be a good idea to pull the right side underbody covers off, inside of the rockers. They cover the steel lines to the rear, maybe there is a pinched section?

[speedracer M]

Did you find the issue? I am suspect of the rear caliper, ATE brand (OEM) caliper rebuild kits are inexpensive or swap the calipers. Maybe a piece of junk or a pitted piston is causing the caliper to bind.

[StephenVA]

He PMed me the other day saying it was the ABS block itself that was clogged up, so it was replaced and now all is fine.