What is best way to clean/purge brake system?
 

Recently, I needed to change brake reservoir grommets (failed inspection for leaking brake fluid). The first part was fairly easy with a turkey baster and a little prying.

My question is what is the best route to take for cleaning the brake system? I've cleaned the reservoir with brake system cleaner but it still is very cloudy, and even black in some areas. There are so many nooks and crannys on the reservoir that I believe it will require replacement.

Should I install the new reservoir before purging the system? or, Should I purge the system with the old one installed and then replace it after the system is flushed?

I'm reluctant to install a new reservoir, purge the system and end up with a new ruined unit. Is there a good method for cleaning the old one?

Answer
 

Flush the system first, then install the new brake reservoir.


Industry Adopts Brake Fluid Replacement Guidelines By Bill Williams, Technical Contributor
http://www.babcox.com/editorial/bf/bf50412.htm

Brake flush every two years?! U'r kidding right?
http://www.peachparts.com/shopforum/tech-help/96852-brake-flush-every-two-years-ur-kidding-right.html

Why should I flush my brake fluid every year, you ask?
http://www.peachparts.com/shopforum/diesel-discussion/38856-why-should-i-flush-my-brake-fluid-every-year-you-ask.html#post220599

Brake bleeder recommendation
http://www.peachparts.com/shopforum/tech-help/72839-brake-bleeder-recommendation.html#post455818

Power Bleeder or what?
http://www.peachparts.com/shopforum/diesel-discussion/103226-power-bleeder-what.html#post707359

Weak brakes, but good pedal feel.
http://www.peachparts.com/shopforum/diesel-discussion/135096-weak-brakes-but-good-pedal-feel.html#post993172

Brake bleed disaster
http://www.peachparts.com/shopforum/diesel-discussion/64278-brake-bleed-disaster.html#post396205

Disappearing Brake Fluid
http://www.peachparts.com/shopforum/diesel-discussion/139187-disappearing-brake-fluid.html#post1033187

HOW do you attach the Resevoir to the Master Cylinder??
http://www.peachparts.com/shopforum/diesel-discussion/142292-how-do-you-attach-resevoir-master-cylinder.html#post1066676

W126 master cylinder and reservoir
http://www.peachparts.com/shopforum/diesel-discussion/116363-w126-master-cylinder-reservoir.html#post826695

Brake system bleeding, master cylinder bleeding
http://www.peachparts.com/shopforum/general-information/149045-brake-system-bleeding-master-cylinder-bleeding-damage-warning.html#post1127978

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Some Facts About Brake Hoses:

#1. The the industry standard average safety life of a brake hose is six years. FYI data SAE: J1401, J1703, J1705, J1873, J1406, J1288, J1403, J1833, J1402.
#2. Brake hoses deteriorate from the inside as well as the outside.
#3. Moisture is absorbed into brake fluid systems through brake hoses.
#4. Contaminants in brake fluid act abrasively on the inner wall of brake hoses.
#5. The brake hose reinforcing fabric deteriorates through expansion and moisture.
#6. High operating temperatures contribute to the deterioration of hoses.
#7. Brake hoses swell with age and restrict flow.
#8. Generally all brake hoses on a vehicle deteriorate at the same rate, So all hoses should be replaced if one is found to be faulty!

Brake hose failure mode:

#A. Rupture (burst hose) = age, exercise (too many miles) or impact are the typical cause.

*B. Partial internal collapse = the inner ply becomes damaged/detached acting as a partial restriction and/or one way valve.

#C. Full internal Blockage = the inner ply becomes damaged/detached acting as a plug = brake pedal still feels good but there is no brake application.

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Brake is a safety system = issues can kill you or others!!!

Be aware of your LEGAL LIABILITY.

http://www.matveylaw.com/CM/Custom/Car-Accident-Causes.asp
http://www.expertlaw.com/library/car-accidents/
http://www.nolo.com/article.cfm/ObjectID/0F1CEF63-DD72-4E9C-A9EFEF37DFC3C5ED/catID/C2B5FF79-6DD8-4FD5-85351429C56DCFFD/104/199/255/ART/
http://www.thebarberlawfirm.com/dallas-car-collisions-lawyer-texas.html
http://www.goldsteinhayes.com/PracticeAreas/Automobile-Accidents.asp

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TYPICAL 'RUBBER' BRAKE HOSE FAILURES
http://www.maltech.com.au/brakehoses.html
http://www.familycar.com/brakes.htm

Incredible data, a must read.
Brakes FAQ Home Volvo Maintenance FAQ for 7xx/9xx/90 Cars
http://www.volvoclub.org.uk/faq/Brakes.html

The Brake Bible
http://www.carbibles.com/brake_bible.html

Bendix Instructional Videos
http://www.bendixbrakes.com/techCorner/

Brakes caught fire 1999 C280 (with pictures of damage)
http://www.peachparts.com/shopforum/tech-help/208962-brakes-caught-fire-1999-c280.html

Tell my dad my tire is on fire! :eek:
http://www.peachparts.com/shopforum/diesel-discussion/105730-tell-my-dad-my-tire-fire-eek.html

gruesome 617 engine pics - don't look if you have a weak stomach
http://www.peachparts.com/shopforum/diesel-discussion/147821-brake-fail-gruesome-617-engine-pics-dont-look-if-you-have-weak-stomach.html



.

Reading some points in your post got me to thinking. Could internal deteriation of the brake hoses be causing the black film in the reservoir?

I replaced the front brake calipers, rotors and pads front and rear about four years ago. While working in the area, I inspected the hoses and noted no hardening or leaking at that time.

If I need to replace the brake hoses, I suspect this will involve a serious bleeding procedure. Hmmm.....the thought of that homemade pressure bleeder comes to mind as I will be doing the procedure by myself.

At this age you should consider replacing all the rubber lines anyway. For now you could flush out the system with some cheaper DOT3 fluid, wait a week, then flush again with DOT4. DOT3 and DOT4 are compatible, DOT4 has a higher boiling point. The new fluid will absorb all the junk in the system, which you can then flush out.

-J

I would think the blackness is an oxidizing of the old brake fuild. I think I remember alcohl as a cleaner for brake systems. Might look for some type of comercial cleaner. I presently use a synthetic brake fluid. I would replace the hoses. If you don't know when they have been replaced last. So, I would replace them.
Replaceing the hoses, doesn't cause any more problems than a regular bleeding procedure. I do use a one man brake bleeder. Two of mine have a one way check valve. The main problem is getting them to stay on the bleeder nipple. Another way I have done it, it to use a board or 2X4 and get it to press the pedal down, then keep it in place with the seat. Then crack the bleeder screw. Repeat process.
Tom
Tom