How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Marty Your Own Question

Marty
Marty, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 53149
Experience:  Bosch Certified Master Technician with over 35 years experience in the automotive industry.
13230946
Type Your Mercedes Question Here...
Marty is online now

We have removed the master cylinder on our 2004 240clk to

Customer Question

We have removed the master cylinder on our 2004 240clk to repair wiring underneath and having replaced the master cylinder the brake servo does not work. The brake pedal performs normally and goes down a little when you start the engine and the servo appears to be making the usual noise when the brake pedal is depressed. We have taken off the master cylinder to make sure the operating rod is correctly aligned and it is. We have pressure bled the system several times and we have a good pedal and can find nothing wrong.Help !
Submitted: 5 months ago.
Category: Mercedes
Expert:  Marty replied 5 months ago.

Hi, my name is***** for the long wait on this question. If you have no power assist when driving the car and braking you will need to check the vacuum to the brake booster. If you have good vacuum to the booster you will probably need to replace the booster. The only other thing I can think of is you lost the o-ring on the end of the master cylinder when you removed it. If the o-ring is missing you will not have power assist.

Let me know what you find.

Marty

What Customers are Saying:

 
 
 
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
< Previous | Next >
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C.
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex
 
 
 

Meet The Experts:

 
 
 
  • Matt

    Matt

    Mechanical Engineer

    Satisfied Customers:

    481
    BEng hons Mech engineering, in auto industry 22 years
< Last | Next >
  • http://ww2.justanswer.com/uploads/35/350matt/2012-6-7_182356_matsavatr.64x64.jpg Matt's Avatar

    Matt

    Mechanical Engineer

    Satisfied Customers:

    481
    BEng hons Mech engineering, in auto industry 22 years
  • http://ww2.justanswer.com/uploads/EU/eurotec/2012-6-11_13153_mpjaphoto.64x64.JPG Marty's Avatar

    Marty

    ASE Certified Technician

    Satisfied Customers:

    21371
    Bosch Certified Master Technician with over 35 years experience in the automotive industry.
  • http://ww2.justanswer.com/uploads/MI/mikeamechanic/2013-4-2_175558_photo.64x64.JPG mike_a_mechanic's Avatar

    mike_a_mechanic

    Mercedes Mechanic

    Satisfied Customers:

    116
    17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
  • http://ww2.justanswer.com/uploads/MB/MBpaul/2013-8-21_204936_paul.64x64.jpg MB Paul's Avatar

    MB Paul

    Mercedes Technician

    Satisfied Customers:

    212
    Mercedes Benz Qualified Diagnostic Technician
  • http://ww2.justanswer.com/uploads/IN/indytech/2013-8-8_102717_SantoDomingo146598x6402.64x64.jpg Greg's Avatar

    Greg

    Technician

    Satisfied Customers:

    1080
    Automotive diagnostic tech
  • http://ww2.justanswer.com/uploads/TE/techmachine/0601821347169_717372168_8940977_39623330_o.64x64.jpg Ross's Avatar

    Ross

    Diagnostic and repair technician

    Satisfied Customers:

    453
    Licensed diagnostic and repair technician