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  #1  
Old 01-28-2008, 09:04 PM
ladams4's Avatar
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Help Please Darn Brakes!

Ok I replaced my Master Cylinder OK the problem I have now is the brake pedal no longer travels to the floor but the pedal seems harder than before and now I have to choke it to turn it off. I checked vacuum lines that i could see under the hood is there a diagram or something I could use? and also just in case you say it is the booster what is the vacuum pressure suppose to be if i get a tester?

Thanks,


I still Love my Benz!!!

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  #2  
Old 01-28-2008, 09:14 PM
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Did you replace the 0-ring between the booster and master cylinder? I'm betting you have a leak between the two somewhere. All the symptoms point to it. 18-21 inches of mercury or thereabouts I think.
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  #3  
Old 01-28-2008, 09:15 PM
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I agree, I bet you forgot the rubber gasket between the M/C and the booster (or didn't realize there was one....I didn't the first time either)
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  #4  
Old 01-28-2008, 09:58 PM
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I'd agree. No shutoff and hard brake pedal = vac leak. Agreed about 20 inches of vacuum. When something like this happens to me, I think back.. What was the last thing I did? That's probably where the problem lies.
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  #5  
Old 01-28-2008, 10:45 PM
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There's an O ring????? Was it suppose to come with the MC? or do you have to get it separate? That makes sense. You Guys are AWESOME! can someone point me in the right direction to fix? This was my first MC i changed with out the guidance of my Big Brother or Uncle


Now please tell me I do not have to drain the fluid again and bench bleed it. can I just unbolt the MC and put the o ring in?
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Last edited by ladams4; 01-28-2008 at 10:53 PM.
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  #6  
Old 01-29-2008, 12:30 AM
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Yup- unbolt it, slide forwards and install o ring.
I bought 2.
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  #7  
Old 01-29-2008, 12:35 AM
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Lind
 
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Ok i took it out now where does the O ring go? on the pin coming out of the booster? or inside the MC?
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  #8  
Old 01-29-2008, 03:35 AM
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Can someone send a pik of this o-ring?

P E H
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  #9  
Old 01-29-2008, 06:36 AM
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Quote:
Originally Posted by ladams4 View Post
Ok i took it out now where does the O ring go? on the pin coming out of the booster? or inside the MC?
Should be a "channel" around the large opening after you separate the MC from the booster. No need to re-bleed, just be careful to not damage the hard brake lines, there is enough room.
May be able to get a pick, will have to wait.
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  #10  
Old 01-29-2008, 06:38 AM
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The o-ring goes between the booster and the m/c. It slips over the end of the master cyl.
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  #11  
Old 01-29-2008, 08:58 AM
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looking at the pic, assuming this is the same mc you bought, where would the oring go?
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  #12  
Old 01-29-2008, 10:10 AM
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I would think it would cover up the unpainted area just in front of the mounting holes , fitting in that smaller "L" shaped groove there.
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  #13  
Old 01-29-2008, 07:12 PM
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Took pics, the ring sets in a channel on the MC, and "nestles" into to booster.
Hope this helps.
Attached Thumbnails
Help Please Darn Brakes!-parts-093.jpg   Help Please Darn Brakes!-parts-099.jpg  
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  #14  
Old 01-29-2008, 08:06 PM
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Toomany,

Yes it helps. I recently replaced a master cylinder (MC) and I was worried I didn't put the o-ring in place. But I installed a used MC so the o-ring would have already been on the replacement MC.

P E H

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