Please Help!Annoying noise from brake booster or pedal after brake fluid replacement.

[woody888]

Hello, everyone.

my F80 is 2018 which is required to change brake fluid this year.

There is a super annoying noise from brake booster or pedal after brake fluid replacement. I'm not pretty sure if it is from booster or pedal. Probably from the booster.

The shop who did the fluid changing work does not use the pressure power Bleeder.
They just release the fluid from caliper and another guy was stepping on the brake pedal several times.

I've tried to apply some lubricant or WD-40 silicone spray inside the booster , but it does not work.

please help if anyone knows what the issue it is.

Thank you so much and really appreciate.

As the videos' link below.

[IVM3]

My squeaking wasn't quite as loud but it turned out to be a bad master cylinder. Replaced it and all is good.

[woody888]

You mean to replace the entire brake booster component?

Originally Posted by IVM3

My squeaking wasn't quite as loud but it turned out to be a bad master cylinder. Replaced it and all is good.

[IVM3]

Originally Posted by woody888

You mean to replace the entire brake booster component?

My issue was not the brake booster, but the actual master cylinder itself. That's the part that the metal rod connects into. You may want to have a shop diagnose it to see if it's the same issue, as it will cost about 1k to replace the master cylinder if you're paying for labor. The part is about 450.

[useewekanet]

Hello mate,

Do you have any news about your problem ?

I have exactly the same problem on my M2, I also tried to put some lubricant but the squeak remains.

Except that the brakes are working really well.
Cheers

[woody888]

Originally Posted by useewekanet

Hello mate,

Do you have any news about your problem ?

I have exactly the same problem on my M2, I also tried to put some lubricant but the squeak remains.

Except that the brakes are working really well.
Cheers

Send you twice Pm. Can't sent it

[useewekanet]

Originally Posted by woody888

Send you twice Pm. Can't sent it

Hello, I also tried to send you a message, did you get it ? Maybe I can't receive PM because I'm a little bit new in this forum ..

[woody888]

Originally Posted by useewekanet

Hello, I also tried to send you a message, did you get it ? Maybe I can't receive PM because I'm a little bit new in this forum ..

1. Refill new brake fluid which is low viscosity . The sticky brake fluid may cause that noise.

2. Before you do the this. , try to do the 1. you may solve problem.
If not, replace a new master cylinder will make the noise gone. At least it works to me,
I replace a new master cylinder with new brake fluid (low viscosity ).

I'm wondering which brake fluid you used for you m2?

The Ate(blue bottle ) I used will cause the noise.

[useewekanet]

Originally Posted by woody888

1. Refill new brake fluid which is low viscosity . The sticky brake fluid may cause that noise.

2. Before you do the this. , try to do the 1. you may solve problem.
If not, replace a new master cylinder will make the noise gone. At least it works to me,
I replace a new master cylinder with new brake fluid (low viscosity ).

I'm wondering which brake fluid you used for you m2?

The Ate(blue bottle ) I used will cause the noise.

Thanks for the tip, so I have an appointment on the 5th of november to BMW garage to check this. I will ask which brake fluid did they put. the problem clearly started appearing after the change of the brake fluid.

Regarding your solution, did you went straight to replace the master cylinder or did you try to flush the brake fluid first ?


Thanks for your help.

Regards.

[woody888]

just replace a new master cylinder with new brake fluid . will fix the issue

Originally Posted by useewekanet

Thanks for the tip, so I have an appointment on the 5th of november to BMW garage to check this. I will ask which brake fluid did they put. the problem clearly started appearing after the change of the brake fluid.

Regarding your solution, did you went straight to replace the master cylinder or did you try to flush the brake fluid first ?


Thanks for your help.

Regards.

[g340ix]

Originally Posted by woody888

just replace a new master cylinder with new brake fluid . will fix the issue

Did you end up replacing the master cylinder or just the fluid? I recently used the ATU type 200, got the squeaky pedal.. then i just flushed again with ate sl.6; the squeak still exists... I'm between trying to bleed a little more, but using the pedal this time instead of the motiv power bleeder, getting another type of fluid(maybe the pentosin) or replacing the master cylinder. Brakes work fine, the noise is driving me nuts though.

Thanks!

[IVM3]

Originally Posted by g340ix

Did you end up replacing the master cylinder or just the fluid? I recently used the ATU type 200, got the squeaky pedal.. then i just flushed again with ate sl.6; the squeak still exists... I'm between trying to bleed a little more, but using the pedal this time instead of the motiv power bleeder, getting another type of fluid(maybe the pentosin) or replacing the master cylinder. Brakes work fine, the noise is driving me nuts though.

Thanks!

It's definitely the ATE typ200 fluid. Flush it again with a low viscocity fluid using the pedal to manually flush.

I ended up replacing the master cylinder and the squeak went away. However, when I flushed the brakes again with ATE a few months later, the squeak came back. I read this is a common issue on Porsches with ATE typ200 fluid. I flushed with bmw low viscocity fluid and the squeak stayed there until after 25 oz of fluid was flushed through. Then it magically went away and has been gone for months now. It's definitely the fluid causing the issue. I'm sticking to bmw fluid now and just flushing more often.

[g340ix]

Originally Posted by IVM3

It's definitely the ATE typ200 fluid. Flush it again with a low viscocity fluid using the pedal to manually flush.

I ended up replacing the master cylinder and the squeak went away. However, when I flushed the brakes again with ATE a few months later, the squeak came back. I read this is a common issue on Porsches with ATE typ200 fluid. I flushed with bmw low viscocity fluid and the squeak stayed there until after 25 oz of fluid was flushed through. Then it magically went away and has been gone for months now. It's definitely the fluid causing the issue. I'm sticking to bmw fluid now and just flushing more often.

Thanks, I'll give it a try with the low viscosity fluid using just the brake pedal this time.

If not I'll try flushing the whole system again using the BMW fluid

[woody888]

Originally Posted by IVM3

It's definitely the ATE typ200 fluid. Flush it again with a low viscocity fluid using the pedal to manually flush.

I ended up replacing the master cylinder and the squeak went away. However, when I flushed the brakes again with ATE a few months later, the squeak came back. I read this is a common issue on Porsches with ATE typ200 fluid. I flushed with bmw low viscocity fluid and the squeak stayed there until after 25 oz of fluid was flushed through. Then it magically went away and has been gone for months now. It's definitely the fluid causing the issue. I'm sticking to bmw fluid now and just flushing more often.

This is what I exact have done. The ATe is too sticky for master cylinder. Just using another brake fluid.

[N1rve]

Wanted to add to this since my F82 with OEM BMW Brake Fluid (Less than 2 years old) is now having a squeaky brake pedal upon release (not on application)

The issue in my case is the Brake Booster. I had no loss of braking power or anything like that. It just squeaks when releasing the brake pedal.

[AlmondJayRoM3]

Originally Posted by N1rve

Wanted to add to this since my F82 with OEM BMW Brake Fluid (Less than 2 years old) is now having a squeaky brake pedal upon release (not on application)

The issue in my case is the Brake Booster. I had no loss of braking power or anything like that. It just squeaks when releasing the brake pedal.

My 2016 F80 brake pedal recently started squeaking upon release. Removed the plastic panel. Just two 10mm nuts. Saw a little bit of grease from that rubber boot covering the plunger to the brake booster. Verified it wasn’t brake fluid, which would obviously be bad. Pulled back the rubber boot towards the pedal exposing the plunger to the brake booster and found dried up old grease and dirt. Cleaned it up and put a thin layer of silicone grease around the plunger and metal rod, pressed the brake pedal in a few times and put the rubber boot back. Squeak went away. You can also use a spray lubricant so it’s easier.

[N1rve]

Originally Posted by AlmondJayRoM3

My 2016 F80 brake pedal recently started squeaking upon release. Removed the plastic panel. Just two 10mm nuts. Saw a little bit of grease from that rubber boot covering the plunger to the brake booster. Verified it wasn’t brake fluid, which would obviously be bad. Pulled back the rubber boot towards the pedal exposing the plunger to the brake booster and found dried up old grease and dirt. Cleaned it up and put a thin layer of silicone grease around the plunger and metal rod, pressed the brake pedal in a few times and put the rubber boot back. Squeak went away. You can also use a spray lubricant so it’s easier.

My car is still having this isssue actually LOL. They replaced the entire brake pedal assembly and the brake booster and the noise is still there. I'll try this silicone grease thing.

[AlmondJayRoM3]

Originally Posted by N1rve

My car is still having this isssue actually LOL. They replaced the entire brake pedal assembly and the brake booster and the noise is still there. I'll try this silicone grease thing.

Did they replace the master cylinder while everything was apart? Some people said their squeak went away with a replacement master cylinder.

[N1rve]

Originally Posted by AlmondJayRoM3

Did they replace the master cylinder while everything was apart? Some people said their squeak went away with a replacement master cylinder.

No, they replaced everything except the master cylinder. Don't know why they did that lol. It's going back again next week.

[N1rve]

Originally Posted by AlmondJayRoM3

My 2016 F80 brake pedal recently started squeaking upon release. Removed the plastic panel. Just two 10mm nuts. Saw a little bit of grease from that rubber boot covering the plunger to the brake booster. Verified it wasn’t brake fluid, which would obviously be bad. Pulled back the rubber boot towards the pedal exposing the plunger to the brake booster and found dried up old grease and dirt. Cleaned it up and put a thin layer of silicone grease around the plunger and metal rod, pressed the brake pedal in a few times and put the rubber boot back. Squeak went away. You can also use a spray lubricant so it’s easier.

What is the trick to pull the rubber boot back?






I'm like pulling on it and it's just not budging.

[N1rve]

For people who will come across this or from a google search, the noise for me also came from the Master Cylinder. I am on OEM BMW brake fluid this whole time so it's not anything to do with the viscosity of the brake fluid. On the work order, the tech also tried to lube the plunger prior to replacing the Master Cylinder and it did not change anything.