Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > X Series > X5 E53 (1999 - 2006)

X5 E53 (1999 - 2006)
The X5 SAV Forum

Thread Tools Display Modes
Old 11-13-2013, 08:21 PM
Kevin Thompson Kevin Thompson is offline
Registered User
Location: California USA
Join Date: Nov 2013
Posts: 1
Mein Auto: Toyota and Suzuki
Brake pedal issues

Hello, this is my first post on this site. I have been a BMW tech for nearly thirty years at both dealer and independent shops. Have an E53 X5 with 4.4 N62 at the shop giving us fits. The booster, master cylinder and vacuum hose with check valve have been replaced. It has been bled three times, including using Autologic software to activate the pump in the ABS system. The pedal is HARD AS A ROCK with the engine shut off, but is mushy when engine running. It will sink to within an inch of the floor with engine running. Driving the car, the soft pedal will almost throw you into the windshield when applied at normal pedal pressure. In simulated panic stops, ABS works and car stops dead straight. Like I said before, pedal is high and hard with engine off, but feels like it is getting WAY TOO MUCH vacuum assist. Has anyone out there heard of this? Customer patient and has spent considerable funds on this problem but it's not right yet. HELP!
Reply With Quote
Old 01-21-2014, 05:28 AM
sy545 sy545 is offline
Registered User
Location: Markham, Ontario, Canada
Join Date: Jan 2014
Posts: 3
Mein Auto: BMW 545i
Pedal going to floor

I have had exactly the same problem for a number of years with my 2004 BMW 545i and it has never been resolved. In addition to the items and work you performed, I also had the DSC unit replaced by my BMW dealership. The brakes were perfect when the car was first purchased.

I am at a complete loss and understand your frustration. As I am not sure if the BMW scan tool was properly used to calibrate the brake pressure, steering angle etc. I will ask for this to be repeated. If this still does not solve the problem, I may consider replacing the vacuum pump though I am not convinced this is the root cause of the problem.
Reply With Quote
Old 01-21-2014, 07:17 AM
Scott ZHP's Avatar
Scott ZHP Scott ZHP is offline
We want the Lion!
Location: PA, USA
Join Date: Jul 2003
Posts: 7,769
Mein Auto: 03 ZHP, 01 X5, 73 MGB
What sort of vaccuum reading do you get at the booster, between the check valve and the booster nipple and is there any evidence of oil?
The N series engines use an engine driven vacuum pump that pukes oil into the boosters; there was a recall for this. But that's usually a loss of boost, not an overboost.

Anything weird at the pedal, or the pivot? There was some flavor of recall for the pedal a while ago, but I doubt that applies to the N62 X5s.

Originally Posted by Fast Bob View Post
JUST...LOOK...UNDER...THE...CAR....for Chrissakes....it`s like checking to see if a dog is male or female....
Originally Posted by smolck View Post
A bimmer with forced induction should have a proper manual gearbox. Anything less is like french kissing your sister.
Reply With Quote
Old 01-21-2014, 09:59 AM
sy545 sy545 is offline
Registered User
Location: Markham, Ontario, Canada
Join Date: Jan 2014
Posts: 3
Mein Auto: BMW 545i
Brake pedal issues

I did not check the vacuum but assume this is good as I am getting brake assist and there is no evidence of oil. The check valve recall was performed before the soft pedal problem several years ago. Prior to the check valve recall, the pedal was hard after sitting overnight and was normal with the engine running. Perhaps this is related.
Based on my research, apparently there is a check valve in the vacuum pump but this fails and BMW sustitutes a check valve in the vacuum line going to the booster. I cannot verify this however.

There is nothing weird at the pedal or pivot.
Reply With Quote

See More Related BMW Stories

Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > X Series > X5 E53 (1999 - 2006)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

All times are GMT -7. The time now is 11:01 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
© 2001-2015 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms