ogrolla Posted March 7, 2015 Report Share Posted March 7, 2015 So I had my MC replaced because I kept loosing fluid and found a leak between the MC and brake booster. New MC now but I still found a leak at the bottom of the booster, also hear air escaping when I pumped the brakes when the car was off. After some online research I learned that when pressing on the pedal will change my idol and the fact that my car is running lean seems that I have a failed brake booster. I assume that the bad MC leaked into the booster and damaged it. Does this sound about right? I want to replace it myself. Seems fairly simple. I want to confirm that If I don't have to remove and brake lines from the MC when replacing the booster then I won't have to bleed the lines. If I do have to bleed them, would I just to a regular bleed at each of my wheels? Since I am replacing it, is there any upgrade for any reason for booster? Car is stock with no engine improvements at this time. Quote Link to comment Share on other sites More sharing options...
LittleRedSpirit Posted March 7, 2015 Report Share Posted March 7, 2015 (edited) Running lean has nothing to do with your brake booster. You gotta think about things yourself, buy a workshop manual, and read it. You might need to remove the master to get at the booster. Remove your old booster to have it tested at a brake shop, they can put vacuum on it and see if it holds it. They can also either rebuild it or sell you a new one, or you can find a spare and have them test it, if its good, bung it in. :clover: Edited March 7, 2015 by LittleRedSpirit Quote Link to comment Share on other sites More sharing options...
lexsmaz Posted March 8, 2015 Report Share Posted March 8, 2015 (edited) A cracked diaphragm in the brake booster can cause a car to run lean but usually only happens when you have your foot is held down on the brake pedal as the diaphragm is then in a stretched state, which will then open up the cracks in it if it's faulty & usually you will hear a hissing sound at the same time you have your foot held down on the brake pedal if the Booster is faulty & the engine idle will change too, if you think its sucking in air all the time listen around the booster with the car running & listen for any hissing sound & if still in doubt remove & plug the vacuum line to the booster from the manifold & see if the car idles better .. Pumping the brakes quickly is normal for it to effect the idle of most cars as it introduces air into the inlet manifold from the brake booster as it cycles .. The best way to test the brake booster is to turn off the car & pump the brake pedal many times & then hold your foot down hard on the brake pedal & then start up the car & If the pedal drops down its working fine .. From the comments you made about your booster I would say its sounds to be ok .. Edited March 8, 2015 by lexsmaz Quote Link to comment Share on other sites More sharing options...
ogrolla Posted March 10, 2015 Author Report Share Posted March 10, 2015 Thank you for the information guys. It does seem that my booster is ok based on the test you described. I guess at this point my only concern is that it seems that its leaking more fluid than before I replaced my MC. I am not loosing anything from the reservoirs it seems. I haven't had a chance to pull off the booster to look at it yet. Maybe there is fluid that has just built up before and its slowing draining..?? Quote Link to comment Share on other sites More sharing options...
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