Weak Brake Pedal

texmexpitt · 08-13-2012, 12:33 AM

I Have 2003 Impala 3.8 that I just installed New Rotors and new pads. I took the caliper off to paint it anyways long story short... when I bled the brakes (with the car off) the brake pedal was very firm but as soon as I started the car my foot went almost completely to the floor. So thinking that I should've had the car on I re-bled the brakes but still the brake pedal felt spongy and my foot goes floor for a complete stop. I would really appreciate any help I can get on this issue

auntjemima · 08-13-2012, 09:18 AM

Are you bleeding the brakes in a particular order or random? Farthest from the master cylinder should be first and alternating thereafter from rear to front.

What you are describing is air in the lines somewhere. You shouldn't have to bleed your master cylinder since you haven't replaced it but it never hurts to do it.

texmexpitt · 08-13-2012, 10:49 AM

Quote:

Originally Posted by auntjemima

Are you bleeding the brakes in a particular order or random? Farthest from the master cylinder should be first and alternating thereafter from rear to front.

What you are describing is air in the lines somewhere. You shouldn't have to bleed your master cylinder since you haven't replaced it but it never hurts to do it.

I bled the brakes RR,LR,RF,LF. Would it matter if the car was on or not? How do you bleed a master cylinder?

**kingnutin** · 08-13-2012, 11:17 AM

Car should be off, you'll pump out too much with the boost. Bleeding the MC usually requires taking it out.

auntjemima · 08-13-2012, 01:49 PM

Correct, you would need to take out the MC ad "bench bleed" it. This is done by making 2 lines that leave the ports and end in the reservoir. Then you could use a rod or a punch to actuate the MC until there were no more air bubbles and then reinstall.

If you are bleeding the wheels properly and still have air then this is generally the next item in the path. Having a pedal that goes to the floor is generally a MC anyways but since it's kinda spongy to you as well I would lean towards air.

08-13-2012, 12:33 AM	#1 (permalink)
texmexpitt Junior Member Join Date: Nov 2010 Location: fort worth, Tx Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts View My Garage texmexpitt	Weak Brake Pedal I Have 2003 Impala 3.8 that I just installed New Rotors and new pads. I took the caliper off to paint it anyways long story short... when I bled the brakes (with the car off) the brake pedal was very firm but as soon as I started the car my foot went almost completely to the floor. So thinking that I should've had the car on I re-bled the brakes but still the brake pedal felt spongy and my foot goes floor for a complete stop. I would really appreciate any help I can get on this issue Attached Images

08-13-2012, 11:17 AM	#4 (permalink)
kingnutin 8th Gen Antagonist Join Date: Mar 2009 Location: Vancouver , WA Posts: 11,805 Thanks: 205 Thanked 535 Times in 362 Posts View My Garage kingnutin	Car should be off, you'll pump out too much with the boost. Bleeding the MC usually requires taking it out. __________________ 1978 Caprice Classic Landau 350 2-bolt, stock 4bbl Stock rebuilt TH350 Edelbrock performer cam + intake Dual 2 1/2" Flowmaster exhuast (waiting to be installed) Edelbrock IAS Classic shocks 95 9C1 3.08 posi 4 wheel disc brakes! 16x8 American Racing Baja's with 225/60/16 Pirelli P4's

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08-13-2012, 09:18 AM	#2 (permalink)
auntjemima Senior Member Join Date: May 2012 Location: Trenton, Ontario, Canada Posts: 1,480 Thanks: 31 Thanked 121 Times in 88 Posts	Are you bleeding the brakes in a particular order or random? Farthest from the master cylinder should be first and alternating thereafter from rear to front. What you are describing is air in the lines somewhere. You shouldn't have to bleed your master cylinder since you haven't replaced it but it never hurts to do it.

08-13-2012, 01:49 PM	#5 (permalink)
auntjemima Senior Member Join Date: May 2012 Location: Trenton, Ontario, Canada Posts: 1,480 Thanks: 31 Thanked 121 Times in 88 Posts	Correct, you would need to take out the MC ad "bench bleed" it. This is done by making 2 lines that leave the ports and end in the reservoir. Then you could use a rod or a punch to actuate the MC until there were no more air bubbles and then reinstall. If you are bleeding the wheels properly and still have air then this is generally the next item in the path. Having a pedal that goes to the floor is generally a MC anyways but since it's kinda spongy to you as well I would lean towards air.

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