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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 07-12-2014, 12:27 PM
Nick6 Nick6 is offline
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brake fluid leak from the hydralic control unit

The other day I started developing a brake fluid leak. I manage to trace it to the hydralic control unit. I'm having fluid coming out of where the black plastic cap is. After reasearching it for a bit I noticed that this doesnt seem to be very common, so I'm wondering did something else fail that is causing fluid to leak out of the hydralic control unit?
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  #2  
Old 07-12-2014, 01:00 PM
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helmet75 helmet75 is offline
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what is the year and production date of your car?
if you dont know the production date, you can get it from your VIN by going to http://www.bmwarchive.org/vin/bmw-vin-decoder.html

I'm pretty sure thats the ABS control module and when you replace it, it must be reprogrammed to match your car. I've never had to do it, but there are plenty of write ups about it.
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  #3  
Old 07-12-2014, 02:53 PM
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bluebee bluebee is offline
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Quote:
Originally Posted by Nick6 View Post
The other day I started developing a brake fluid leak. I manage to trace it to the hydralic control unit. I'm having fluid coming out of where the black plastic cap is. After reasearching it for a bit I noticed that this doesnt seem to be very common, so I'm wondering did something else fail that is causing fluid to leak out of the hydralic control unit?
I don't see the leak (is it the blue ?) but if it's exactly there at the ABS control module, then you are correct. It's not common.

For pictures of what it looks like behind that ABS control module, check here:
- How to diagnose the BMW amber ABS BRAKE DSC/ASC trifecta or bifecta (1)

But, you might also want to check your rubber brake lines (which are nearby):

- How to identify and replace all E39 brake hoses (1) (2) & brake pipes (1) (2)
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Each repair should invariably add to our knowledge base by the process of inexorable incrementalism.
Your job, in return, is to read the suggested threads, where the best people will always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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  #4  
Old 07-12-2014, 10:17 PM
Nick6 Nick6 is offline
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The leak is the blue fluid coming from the plastic cap. With the cap removed, fluid shoots out of that area everytime the brakes are used.


Brake lines were replaced about a year ago and replaced with stainless steel.
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  #5  
Old 07-12-2014, 10:34 PM
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bluebee bluebee is offline
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Quote:
Originally Posted by Nick6 View Post
The leak is the blue fluid coming from the plastic cap. With the cap removed, fluid shoots out of that area everytime the brakes are used.
Dunno what's supposed to happen when that cap is removed; so, let's see if someone pipes in with experience on that.

Quote:
Originally Posted by Nick6 View Post
Brake lines were replaced about a year ago and replaced with stainless steel.
I think you missed the point, but, in the end, it probably doesn't matter because I took a closer look at your pictures and I can see at least one of those two rubber brake lines, but it appears, at least in your picture, to be in good shape (so that's not where the leak is coming from anyway).
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Each repair should invariably add to our knowledge base by the process of inexorable incrementalism.
Your job, in return, is to read the suggested threads, where the best people will always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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  #6  
Old 07-13-2014, 10:10 AM
cn90 cn90 is offline
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Post better photo with arrow pointing to the problem area.
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  #7  
Old 07-13-2014, 10:44 AM
Nick6 Nick6 is offline
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Just checked those upper rubber lines. They appear to be fine, no leaks or seapage.
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  #8  
Old 07-13-2014, 11:07 AM
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bluebee bluebee is offline
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Quote:
Originally Posted by Nick6 View Post
Just checked those upper rubber lines. They appear to be fine, no leaks or seapage.
Thanks. You understood what/where I was talking about!
This is an unusual problem, if, indeed, you're leaking from the hydraulic unit itself, so, I'd annotate the picture as cn90 suggested (he knows a LOT about this stuff - so I will bug out).

If you need help in annotating, typing /annotate f3 in the bestlinks nets this:
- How to post, shrink, modify, edit, annotate, merge, & upload pictures for posting here (1)
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Each repair should invariably add to our knowledge base by the process of inexorable incrementalism.
Your job, in return, is to read the suggested threads, where the best people will always add value to those threads, either by pictures or by descriptions, so the next person with the same problem stands on your shoulders.
See also: E39 Bestlinks & How to easily find what you need
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  #9  
Old 07-13-2014, 11:10 AM
Nick6 Nick6 is offline
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The lights I'm getting on are the yellow dsc and red 'brake' lights. No abs.
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  #10  
Old 07-13-2014, 11:42 AM
Nick6 Nick6 is offline
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Quote:
Originally Posted by cn90 View Post
Post better photo with arrow pointing to the problem area.
.
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