Brake pedal affecting idle?

[blocke]

Mods, not sure if this belongs in Brake Sub-forum. If so, please move.

So I just got done rebuilding my calipers, new lines, pads, and bled the system with motive power bleeder using ATE Blue. Car drives fine, brakes are great.

I have noticed however, that my idle is higher now, about 1100. And when I pump the brake pedal, it will slightly rise with each pump, and then gradually fall back down.

I understand the booster affects manifold pressure, but need help getting around what I might have done to cause this. Maybe the bleeder f'd something up? Im stumped.

Ideas?

[FLG]

Could be a bad diaphragm in the booster causing a vac leak. When you shut the car off does the brake pedal immediately get hard or do you have a good pump or two of the pedal before that happens?

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[jlevie]

Yep, a change in idle when the brake pedal is pressed suggests a leaking brake booster.

[blocke]

Is the booster the only possibility? Blown seals, or a bad check valve wouldn't do this? The Bentley doesn't describe a test procedure, just says if is bad it must be replaced.

[FLG]

Bad check valve will cause you to lose pressure when the car is turned off giving you no power assist for those one or two pumps if you needed them but won't cause a idle problem. Problem lies within the booster.

If you have a hand vac pump you could disconnect the booster and see if it holds vac but that's about it.

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[blocke]

Damn. So if I have to replace it, any option to upgrade while I'm at it? I've seen 7 series boosters floating around. That would just give me reduced pedal pressure required?