545iBMW

Short story - it happened to me 4 times the past 2 months or so.
Three times, I was driving between 20-40mph, pressed the brakes to stop - felt like I was stepping on a brick but no brake pressure. VERY SCARY!

Last night, I was driving at the interstate doing ~75mph and almost hit a van.
First two pumps, felt like stepping on a brick, no brake pressure.


I don't think this is due to cold weather, it was in the 80's last night.
I also don't think it's caused by air inside my brake system. It doesn't feel spongy, it felt like a literal brick on my brake pedal with no brake feel, I wasn't slowing down and it felt like a roller coaster going down the coast with no brakes!

I searched online and seems like people were able to get this fixed by replacing the valve check - how hard/easy is this to DIY?
Some people were able to get this fixed by replacing the brake booster - seems an expensive job.
I have not replaced by brake fluid (was supposed to be due last December) but I'm planning to do this this weekend. But I'm "brick" issue is not just related to the fluid.

Can someone enlighten me? Hopefully this will help others too.

TY.

Ricracing

Hi 545iBMW,

Scary story!

Doesn't the iDrive tell you something?

You need to have a break service at once, at the dealers.
When did you serve your car at the dealers and reset the iDrive?

It could be a faulty brake booster, water in the brake fluid or
worn out brake pads or even disks.
The fluid must be changed ever second year.
The pads, front at some 30 - 40 k miles, the rear pads at some 60-70 k miles.
The disks need to be changed at every second pad change.

And don't forget the iDrive sensors!

spandex

I didn't realise this was a known problem on N62 cars.. I bought a 645 about a year ago and within 24 hours of owning it had experienced exactly the same symptoms you describe (it was also pretty cold at the time). The independent dealer I had bought it from agreed to pay for any repairs, but after a few weeks of BMWs incompetence (in other words, their standard response of "there's no fault code telling us what to do, so we'll randomly replace components at your expense") I still wasn't confident it was going to stop when I needed it to, so I returned the car and got a refund. I'm now in a 545i and this doesn't appear to have the same fault (so far) despite a pretty cold winter here.

Although a few people tried to tell me at the time that they thought it was the master cylinder, I was pretty sure it must be related to the booster (or the vacuum system that powers it), as a failed master cylinder would cause a spongey brake, not a hard one. If it was the valve or the vacuum pipework, it could also explain why the cold weather affects it (maybe the temperature hardens the rubber, or contracts metal to affect the seal). It's also worth visually inspecting the vacuum pipe to see if it looks at all perished.

Anyway, I'm curious to see if you find a fix for this. Good luck.

545iBMW

My warranty expired on December 2009.

Last year, I brought my car when my car "leaned" on one side (forgot what the error on the iDrive).
They said it was my tire loosing air (I don't drive the car too much)
So they put air on it and went OK. This happened about 1st quarter of 2009.

I had that same issue again and told me it was the air again.
Or maybe the battery. So they replaced the battery (had to talk hard to get them cover for parts and labor).

Third time, my new battery died. They replaced the alternator. YEAH!

Then, I had have no problems except when I had to send the car for the seat airbag recall.
All these 4 visits, they said they had to reprogram the car (well, that's according the the SA).

The guy who sold me a set of 172's last night work at the dealership.
He was so friendly, he told me to call him if I need parts or need to have something done. He's a BMW mechanic by the way.
Called him today and offered to scan my car next weekend for FREE!

I loveeeeeeeeeee this car - my brain tells me to pretend nothing is wrong with it.
But this is safety related and want to get it looked at sooner or later.

Oh, about the brake fluid that needs to be replaced every 2 years, I was supposed to do that next weekend too. Thanks all.

545iBMW

Found these old threads last night:

https://5series.net/forums/topic/779..._fromsearch__1

https://5series.net/forums/topic/938...&#entry1109929

545iBMW

Just want to update this.
I finally got fed up and called BMWNA to complain about this.
BMWNA told me to call my local dealer and talk to the manager and tell them the issue.
Afterwards, they will determine my "compensation".

Dropped off the car yesterday morning.
Didn't get any call so I gave them a buzz.
SA told me that the manager is already talking to BMWNA about my car.

I hope this turns out well.
They gave me a free BMW loaner even if I'm out of warranty.

turboawd

sounds like you have a vacuum issue. the power brakes work off vaccum. you must have a bad brake booster, vaccum lines, vacuum pump, or similar.

545iBMW

Yeah, thats what the SA told me.
I've also read a bunch of these going bad here at the forum but I'm surprised its not recalled yet.
This is a major safety issue and this should be escalated.

SmG-Deuce

This is weird my brother have a 645 and he just told me he's having the same exact problem

545iBMW

I think this is pretty common issue and I'm surprised, BMW is not doing anything to solve this.


Anyhow, dealer is charging me $1200 to replace vacuum pump, check valve and hoses.

Can anyone pinpoint these parts for me from the diagram? How easy is this to DIY?
I will check with my local indie center to see how much this would cost me.

Thanks.



LINKY