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  #1  
Old 11-09-2006, 08:39 PM
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help! brakes won't bleed!

Hello,
I have a 1984 300sd. I reaplced two calipers all rotors and pads. I went to bleed the brakes. the rear brakes seemed to bleed fine with one person pumping the brake pedal and the other manning the tube. I went to bleed the front brakes and they will not bleed. THe fuid in the rservoir will not go down. Am I doing something wrong?
Thanks for your help,
Benjamin
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  #2  
Old 11-09-2006, 08:50 PM
Wodnek's Avatar
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Try a mighty Vac on the bleeders. Suck the fluid through.
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  #3  
Old 11-09-2006, 09:23 PM
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I used a Motive Power bleeder and it worked great after having similar problems. Needed about 25 pounds to get it to work! My 87 preferred a pressure pump in contrast to a vacuum..I bought it as I can use it on all my other cars too. Good Luck
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  #4  
Old 11-09-2006, 10:02 PM
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you might want to open up the bleeders and just let them gravity bleed for a while. if this won't work, did you replace the flex hoses when you replaced the calipers? it is known that flex hoses can deteriorate internally and plug up. try disconnecting the lines from the calipers and see if any fluid is flowing from them at all. if so, you may have defective calipers...or, did you perhaps have rubber plugs in the line holes, and not get it all out?
John
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"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

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  #5  
Old 11-10-2006, 12:57 AM
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Quote:
Originally Posted by popimor View Post
Hello,
I have a 1984 300sd. I reaplced two calipers all rotors and pads. I went to bleed the brakes. the rear brakes seemed to bleed fine with one person pumping the brake pedal and the other manning the tube. I went to bleed the front brakes and they will not bleed. THe fuid in the rservoir will not go down. Am I doing something wrong?
Thanks for your help,
Benjamin
You need to explain this better for us.

If the bleeder screw is open and you press down on the pedal........does any fluid come out of the bleeder? Does the pedal go almost all the way down to the floor (the one system is fully compresses in the m/c)? Or, does the pedal feel normal and no fluid is coming out of the bleeder?

It's almost impossible not to have fluid drain from the m/c if the bleeder is truly open.
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  #6  
Old 11-10-2006, 09:24 AM
LarryBible
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You will need to run the engine in order to successfully use the two man method UNLESS you have a REAL man at the pedal. If you have someone who is not willing or able to apply STRONG pedal pressure, you will need the help of the brake booster.

Roll down all the windows so the helper can hear you and you can hear them. Make SURE that the car is in neutral or park and that the e brake is set hard.

I promise you that this will work. The operation of the booster makes all the difference.

I personally will NOT bleed brakes with a hand grip vacuum source. The Motive bleeder works good.
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  #7  
Old 11-10-2006, 09:48 AM
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Answer:

Quote:
Originally Posted by popimor View Post
Hello,
I have a 1984 300SD. I replaced two calipers all rotors and pads. I went to bleed the brakes. the rear brakes seemed to bleed fine with one person pumping the brake pedal and the other manning the tube. I went to bleed the front brakes and they will not bleed. The fluid in the reservoir will not go down. Am I doing something wrong?
Thanks for your help,
Benjamin
The proportioning valve has activated:
Fill the reservoir to the top, attach hose to each bleed screw running into a clear bottle, open both FRONT caliper bleeders and one REAR bleeder, WARNING/DANGER: keep the master cylinder full at all times,
allow to gravity bleed until you have front flow.

A pressure bleed will fix your issue in a few moments.

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

Brake bleeder - power bleeder Homemade
Brake bleeder - power bleeder Homemade

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

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



TYPICAL 'RUBBER' BRAKE HOSE FAILURES
Click the picture to really see the failure.
http://www.cebcobrakes.com.au/html/s02_article/article_view.asp?id=117&nav_cat_id=137&nav_top_id=61&dsa=1

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

Counter Pro Online Training Course: Brake Basics
http://www.raybestos.com/OnLineTraining/cpt-005.htm

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?
Brake flush every two years?! U'r kidding right?

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



Have a great day.
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  #8  
Old 11-10-2006, 11:38 AM
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I had similar problems bleeding the rear breaks on my 240D a few weeks ago. I found out that the break fluid reservoir had two chambers, and the one that supplied the rear was empty. I had to fill the main res. to almost overflowing for the rear res to get any fluid. So I had to nearly overfill the main res several times to fill up the rear res. You might look carefully at the res. on top of the booster to see if you can see if it has two chambers.
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  #9  
Old 11-10-2006, 11:44 AM
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Quote:
Originally Posted by LarryBible View Post
I personally will NOT bleed brakes with a hand grip vacuum source. The Motive bleeder works good.
Why won't you bleed brakes with a hand grip vacuum source? Is pressure bleeding better? I have used my Mitevac on two cars now and I have had great results.
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  #10  
Old 11-10-2006, 11:48 AM
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I had to replace those little black caps (2) on the reservoir before I could get the brakes bled. At first sight they looked ok but I replaced them anyways and then I could bleed the brake...
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  #11  
Old 11-10-2006, 01:36 PM
LarryBible
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There is a difference in bleeding and flushing. If you are simply flushing, the mityvac can get the job done, although AFIAC it is much more hassle than just finding a helper.

Bleeding is something else though. The MityVac often cannot provide enough volume to flow fast enough that the air bubbles do not rise faster than you can pull the fluid out.

On a lot of later cars with ABS, vacuum bleeding can cause lots of trouble. It's just best practice to use a pressure bleeder or the two man method.

If the mityvac works for you, then that's great, but beware that it may cause some trouble along the way.
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  #12  
Old 11-10-2006, 04:22 PM
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Answer:

Quote:
Originally Posted by riethoven View Post
Why won't you bleed brakes with a hand grip vacuum source? Is pressure bleeding better? I have used my Mitevac on two cars now and I have had great results.
Here is a technical answer to your question.
http://brakebleeder.info/technical.html
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  #13  
Old 11-10-2006, 04:32 PM
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Quote:
Originally Posted by whunter View Post
Here is a technical answer to your question.
http://brakebleeder.info/technical.html
Do you use the RFI reverse flush method that they show? It makes sense to me that it would work better than pressurizing the reservoir.
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  #14  
Old 11-10-2006, 04:40 PM
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Quote:
Originally Posted by LarryBible View Post
There is a difference in bleeding and flushing. If you are simply flushing, the mityvac can get the job done, although AFIAC it is much more hassle than just finding a helper.

Bleeding is something else though. The MityVac often cannot provide enough volume to flow fast enough that the air bubbles do not rise faster than you can pull the fluid out.

On a lot of later cars with ABS, vacuum bleeding can cause lots of trouble. It's just best practice to use a pressure bleeder or the two man method.

If the mityvac works for you, then that's great, but beware that it may cause some trouble along the way.
I guess I am really flushing the last time I worked on my wife's car. She needed rear pads and it was fluid change time. The calipers were fine to I just added fluid to the reservoir and sucked it through the system. However when I did the brake job on my car I had all four calipers off when I replaced them and the rubber lines. I made the mistake of losing the prime on the master cylinder and I could not get it to bleed until I got the Mitevac, then I was able to draw the fluid through the system. I also pulled the reservoir off and cleaned all the sludge out of it. The fluid had not been changed in a long time.

I appreciate the tip on vacuum bleeding cars with ABS. When I get my W124 up and running I will not use the Mitevac to flush the brakes.
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  #15  
Old 11-10-2006, 06:16 PM
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Answer:

Quote:
Originally Posted by riethoven View Post
Do you use the RFI reverse flush method that they show? It makes sense to me that it would work better than pressurizing the reservoir.
I use every method listed there, depending upon circumstances.

I do like the reverse flush method, and have used it with great success since 1969..

How they dare to claim the method as theirs is beyond my comprehension.
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