QuickSilver 0 Report post Posted July 13, 2008 Car: 1987 Pre-face lift E30 320i 4 door 5 speed manual. Problem: The brakes in the morning don't seem to have as much pressure as normal, this has happened twice now, not on a regular basis, the last time was about 3 weeks ago, and then again this morning, the pedal would need to pushed much further down to have the same effect as it would normally have, they don't seem to be weaker, but just need to push much further. After driving a while, pressure will return and there wont be any problem, and if left parked for a while, it will remain the same, and also would be fine the next day. The last time this happened it was colder than usual in the morning, I don't know if this will attribute to anything. Checked: I have checked the fluid level and cant see a noticeable drop which would rule out a leak of some sort? And if there was a fluid leak I'm sure my brakes would fail completely, The other thing I thought it may be is old fluid, its not dis-colored or anything but I know that old fluid can lose pressure, does this sound like it could be causing it? Recent wok done: The only thing that I have done in the last month that could POSSIBLY is when I replaced my ICV, as I had to disconnect the vacuum lines that run to the brake booster from the intake manifold, although I don't think that this would cause this problem. Any info would be hugely appreciated, let me know if there is any additional info needed. Thanks Alex. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted July 14, 2008 Sounds like it could be a leak from the booster vacuum line. Is the idle OK ?? Or it might be a sticking one way valve on the booster or the booster itself Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted July 14, 2008 Idle now that you mention it sometimes revs a little high but not for too long, and occasionally seems to hunt for about 50 - 80 rpm up and down at idle, is this a symptom? Do you mean the vacuum lines that connect to the intake manifold and to the booster? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted July 14, 2008 Idle now that you mention it sometimes revs a little high but not for too long, and occasionally seems to hunt for about 50 - 80 rpm up and down at idle, is this a symptom? Do you mean the vacuum lines that connect to the intake manifold and to the booster? Yes the vacuum line to the booster, if it leaks it would upset the idle as well and not give enough vacuum for the booster to work properly Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted July 14, 2008 That would explain both issues! Is there any easy way to test for a vacuum leak? Ill replace them just to be safe anyway. Thanks a million Glenn! Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted July 14, 2008 That would explain both issues! Is there any easy way to test for a vacuum leak? Ill replace them just to be safe anyway. Thanks a million Glenn! It may not be that though. I was only suggesting what to check. It could be a sticking one way valve or the booster itself. Bit hard to diagnose from here. Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted July 14, 2008 (edited) Ok yeah I understand, I guess I will have to go by process if elimination, if I had the time I would pop out but its a bit of a drive for me, thanks for your help! Alex. Edited July 14, 2008 by QuickSilver Quote Share this post Link to post Share on other sites
Creaver 55 Report post Posted July 14, 2008 (edited) My mates e30 has hunting idle and a very squishy brake pedal at all times, would this also contribute? Can you explain how this leak makes the pedal softer as opposed to harder please? Edited July 14, 2008 by Creaver Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted July 14, 2008 Lack of vacuum to the booster makes the pedal go hard and you loose braking efficiency. You need to push a hell of alot harder to get it to stop. Wont make it go squishy though. Quote Share this post Link to post Share on other sites
CamB 48 Report post Posted July 14, 2008 An internal leak in the master cylinder will make the brake pedal go soft. It's a disconcerting feeling of having the pedal sink slowly beneath your foot while sitting at the lights, or a long soft pedal (and if it is bad enough, you need to pump the pedal). It doesn't sound from the description like this is the problem, but in case this describes it... there you go. Quote Share this post Link to post Share on other sites
QuickSilver 0 Report post Posted July 15, 2008 Not quite the same issue, mine just seems to do it when cold, after a while it regains pressure and goes back to normal, when its not normal the only thing thats needed is a deeper/harder push on the pedal, but the braking still works fine, just more effort required, im checking it out today/tomorrow. Quote Share this post Link to post Share on other sites
Creaver 55 Report post Posted July 15, 2008 Thank you all, sorry to somewhat hijack thread. Quote Share this post Link to post Share on other sites
