I just noticed after replacing my power brake booster after having it rebuilt that my engine Idle surges by about 300 rpm and then calms back down everytime I come to a stop. Brakes are mushy, not firm, not sure this has anything to do with the issue, I've bleed them 3 times, might have to go back for a fourth, but again not sure this is related. Any direction would be appreciated. Don
Surging Idle upon coming to a stop
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Moondoggie
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Sounds like you may have a vacum leak in that new booster. Was it tested before you installed it ??
Moondoggie
Moondoggie
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It Can Happen
Yup: There is a rocking "T" bellcrank in those servos that re-directs the vacuum air each time you either push down or let off the pedal. If those little "hat" seals on it are not seating well, you will get the exact symptom you mention. There can also be any other number of internal "quirks" that could cause the mushy pedal, but I would start at the master first to eliminate that end.
Yup: There is a rocking "T" bellcrank in those servos that re-directs the vacuum air each time you either push down or let off the pedal. If those little "hat" seals on it are not seating well, you will get the exact symptom you mention. There can also be any other number of internal "quirks" that could cause the mushy pedal, but I would start at the master first to eliminate that end.
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It's been awhile since I rebuilt a booster...if you have brake fluid passing by the booster into the intake manifold, I seem to remember the rpm's rising until the brake fluid burned off- of course, you'd see some grayish colored smoke coming out the exhaust if that was happenining.