E36 Brake Woes

RodneyWright · **Posted:** Sun Nov 19, 2006 12:17 am

I hope everyone has a blast tomorrow. I'm going to have to bail. Have some brakes issues that have surfaced and I don't want to push the bimmer into a bad situation. This course sounds like a blast...even installed my race seat!!

As for my brake problem, if anyone can help answer the following, I'd be grateful for some direction. In bleeding the brakes either by pedal or power bleeder, I can get the pedal rock hard. Start the car up and the pedal gets spongy and then will slowly sink to the floor. Turn the car off and pump the pedal and it gets hard again. I think my master cylinder is gone. No leaks anywhere that I can tell.

Let me know what you think..

Thanks and have fun tomorrow.

steve remchak · **Posted:** Sun Nov 19, 2006 12:28 am

RodneyWright wrote:

I hope everyone has a blast tomorrow. I'm going to have to bail. Have some brakes issues that have surfaced and I don't want to push the bimmer into a bad situation. This course sounds like a blast...even installed my race seat!!

As for my brake problem, if anyone can help answer the following, I'd be grateful for some direction. In bleeding the brakes either by pedal or power bleeder, I can get the pedal rock hard. Start the car up and the pedal gets spongy and then will slowly sink to the floor. Turn the car off and pump the pedal and it gets hard again. I think my master cylinder is gone. No leaks anywhere that I can tell.

Let me know what you think..

Thanks and have fun tomorrow.

track that BMW did you Rodney? while i can't say my last issue is the same as your current one, it does sound similar. seems an E36 will cause brake pads to wear unevenly, with more wear in the middle of the pad and thusly reward you with a spongey pedal.

bring it on out to Sanford and wear down the outside edges of the pads.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

RodneyWright wrote:

I hope everyone has a blast tomorrow. I'm going to have to bail. Have some brakes issues that have surfaced and I don't want to push the bimmer into a bad situation. This course sounds like a blast...even installed my race seat!!

As for my brake problem, if anyone can help answer the following, I'd be grateful for some direction. In bleeding the brakes either by pedal or power bleeder, I can get the pedal rock hard. Start the car up and the pedal gets spongy and then will slowly sink to the floor. Turn the car off and pump the pedal and it gets hard again. I think my master cylinder is gone. No leaks anywhere that I can tell.

Let me know what you think..

Thanks and have fun tomorrow.

With the car running and steady pressure on the pedal, if the pedal slowly sinks, it's definitely a bad master cylinder (or less likely a major brake fluid leak somewhere, which you would be able to find).

Spongy but able to be pumped up (with the car running) just means air or excessive clearance somewhere. If you have replaced any calipers recently, sometimes it can take a good 4-6 bleed cycles to get every bit of air out.

Behavior with the car not running doesn't matter, since you're just feeling the brake boost being bled off. Do all your testing with the motor running.

RodneyWright · **Posted:** Sun Nov 19, 2006 2:16 pm

Well, I think I've come to conclusion as to what's wrong. Been reading bimmerforums (and sifting thru the junk posts) and looked over the bentley manual and have it narrowed down to a bad master cylinder. Fails the bentley test for pumping the brakes up 10 times with the engine off and then turning on the engine with your foot still on the brakes. According to the manual, the brake pedal should fall "just a bit" after you turn on the engine. Mine falls completely to the floor.

rats....

Wes Eargle · **Joined:** Mon Oct 27, 2003 9:47 am **Posts:** 3683

I had the same problem in both of my cars. Fortunately, it's a simple swap. Just make sure to "bench bleed" the MC. Air in the lines = bad.

Matt McGrain · **Posted:** Sun Nov 19, 2006 6:41 pm

RodneyWright wrote:

Well, I think I've come to conclusion as to what's wrong. Been reading bimmerforums (and sifting thru the junk posts) and looked over the bentley manual and have it narrowed down to a bad master cylinder. Fails the bentley test for pumping the brakes up 10 times with the engine off and then turning on the engine with your foot still on the brakes. According to the manual, the brake pedal should fall "just a bit" after you turn on the engine. Mine falls completely to the floor.

rats....

Good luck with that replacement Rodney. Just out of curiousity, did you notice the responsiveness or 'bite' start to fade before the failure? The reason I ask is that my brakes in the Integra don't seem to have to power they did last year and that may be the culprit for me as well.

steve remchak · **Posted:** Sun Nov 19, 2006 8:09 pm

RodneyWright wrote:

Well, I think I've come to conclusion as to what's wrong. Been reading bimmerforums (and sifting thru the junk posts) and looked over the bentley manual and have it narrowed down to a bad master cylinder. Fails the bentley test for pumping the brakes up 10 times with the engine off and then turning on the engine with your foot still on the brakes. According to the manual, the brake pedal should fall "just a bit" after you turn on the engine. Mine falls completely to the floor.

rats....

sorry too hear that Rodney. was hoping it was only the pads. great autoX today BTW.

RodneyWright · **Posted:** Sun Nov 19, 2006 11:10 pm

Matt McGrain wrote:

Good luck with that replacement Rodney. Just out of curiousity, did you notice the responsiveness or 'bite' start to fade before the failure? The reason I ask is that my brakes in the Integra don't seem to have to power they did last year and that may be the culprit for me as well.

The car has always had what I thought was a soft pedal, but I just learned to live with it. After the HPDE, I had problems with the brakes and a very soft pedal. Bled the brakes Sunday morning and they felt great. After Sunday's run, the pedal went soft again. Bled it again Monday evening and finally had the pedal I thought the car needed. Seems working over the ABS pushed out some hidden air.

In reading over the bimmerforums, seems that engaging the ABS is a somewhat effective way to aid in bleding the brakes. My problem showed up when I just changed the pads this weekend to get ready for the last autox. After I pushed the piston back into position and to put the pads, I ran into issues.

I never was able to get the pedal to firm back up. Bled the brakes 4 times, twice by pedal pressure and twice by a power bleeder. That's when I tried the bentley manual test and it failed. Only conclusion is a bad MC. This is one battle I won't fight. Off to Daves tomorrow and hopefully he can put me back on the road.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

RodneyWright wrote:

Matt McGrain wrote:

Good luck with that replacement Rodney. Just out of curiousity, did you notice the responsiveness or 'bite' start to fade before the failure? The reason I ask is that my brakes in the Integra don't seem to have to power they did last year and that may be the culprit for me as well.

The car has always had what I thought was a soft pedal, but I just learned to live with it. After the HPDE, I had problems with the brakes and a very soft pedal. Bled the brakes Sunday morning and they felt great. After Sunday's run, the pedal went soft again. Bled it again Monday evening and finally had the pedal I thought the car needed. Seems working over the ABS pushed out some hidden air.

In reading over the bimmerforums, seems that engaging the ABS is a somewhat effective way to aid in bleding the brakes. My problem showed up when I just changed the pads this weekend to get ready for the last autox. After I pushed the piston back into position and to put the pads, I ran into issues.

I never was able to get the pedal to firm back up. Bled the brakes 4 times, twice by pedal pressure and twice by a power bleeder. That's when I tried the bentley manual test and it failed. Only conclusion is a bad MC. This is one battle I won't fight. Off to Daves tomorrow and hopefully he can put me back on the road.

Rodney, keep us posted on how the MC fix works. I remember now the one time I did a fun run in your car earlier this year that I told you after the run "your brakes ain't right". The pedal was really unresponsive. Based on what you said above I'm still not completely sure that it's a bad MC (in the typical sense of a leaky seal on the piston) but it certainly sounds like it. It's an interesting problem. Brake stuff is always challenging.

Scott Johnson · **Posted:** Mon Nov 20, 2006 8:16 am

RodneyWright wrote:

My problem showed up when I just changed the pads this weekend to get ready for the last autox. After I pushed the piston back into position and to put the pads, I ran into issues.

Did you crack a bleeder screw before pushing the piston back in? I can think of only bad things that can happen if you push that nasty old fluid back into the system.

Best case, you just reverse-flushed the system with nasty old fluid, worst case, I think I've heard of ABS pumps that get really unhappy when that happens (but that could be an old wives tale).

Scott

Chuck Branscomb · **Posted:** Mon Nov 20, 2006 8:57 am

MikeWhitney wrote:

Rodney, keep us posted on how the MC fix works. I remember now the one time I did a fun run in your car earlier this year that I told you after the run "your brakes ain't right". The pedal was really unresponsive. Based on what you said above I'm still not completely sure that it's a bad MC (in the typical sense of a leaky seal on the piston) but it certainly sounds like it. It's an interesting problem. Brake stuff is always challenging.

Does the E36 have hydraulic assist or vacuum? I recall a similar symptom on my E28 535i (granted, this memory is now close to 20 years old so...) that I was SURE was a master cylinder issue. It turned out to be the now infamous E28 "bomb" hydraulic accumulator. I think my 535 went through two of these before BMW got the thing revised. It was called the bomb since it looked just like a round, black bomb.

Chuck

Graham Jagger · **Joined:** Fri Aug 29, 2003 12:53 am **Posts:** 1718

How did part of the Sanford thread from the AX section become an E36 thread in the Tech Section???

Ryan Holton · **Posted:** Tue Nov 21, 2006 11:35 am

Graham Jagger wrote:

How did part of the Sanford thread from the AX section become an E36 thread in the Tech Section???

I split it and must have screwed it up. It seemed as if it had veered off course and I tried to split the "Brake Woes" from "Sanford talk"

jimpastorius · **Posted:** Tue Nov 21, 2006 11:53 am

Graham Jagger wrote:

How did part of the Sanford thread from the AX section become an E36 thread in the Tech Section???

Probably some mention in there about having lousy tires. The tires are attached to rims that bolts to hubs, that have brakes attached....so lousy tires are indirectly related to brakes :-)

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Ryan Holton wrote:

Graham Jagger wrote:

How did part of the Sanford thread from the AX section become an E36 thread in the Tech Section???

I split it and must have screwed it up. It seemed as if it had veered off course and I tried to split the "Brake Woes" from "Sanford talk"

I think you selected "Split from selected post" instead of "split selected posts".

I put the relevant Sanford posts into another thread "Part Deux" since I want this one to stay clean

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