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usmcbrowns
Samba Member
Joined: July 02, 2015
Posts: 60
Location: Sneads Ferry, NC
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 Posted: Fri Mar 16, 2018 11:23 am Post subject: Brake Bleeding Nightmare |
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Okay... New Master Cylinder, and also bleeding brakes.
Bench bled the MC twice. When we bleed the brakes, the rear pedal only goes 1/2 down when the bleeder is opened. It just stops and wont go any further than 1/2 way to the floor. When the front bleeders are open, pedal travels to the floor.
Bled the brakes 10 times now. Even cracked the brake switches and bled them. When i'm staring at the MC, and someone pumps the brakes it looks as if i can see big air bubble at the inlet port of the MC front (furthest inlet from the pedal) So.. the front portion. I repositioned the lines coming from the reservoir as to maybe let the air bubble go to the top. After a while i didn't see the air anymore. I THINK....
Anyway, bled the brakes again.... still no difference. Brakes are not good.
Thought maybe its just my mind. Put the tires on... Brakes have to go to the floor just to get it to sort of slow down.
Also... brake lights wont go on until pedal is at least 1/2 way to the floor.
I'm at my wits end.
Anyone?????
Thanks.
Mark
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71 Super Beetle, 1641
2011 Ram 2500 Diesel
2013 GMC Acadia
2014 Stingray
2004 KLR 650 |
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beetlenut
Samba Member
Joined: May 27, 2009
Posts: 2983
Location: RI
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| Posted: Fri Mar 16, 2018 12:34 pm Post subject: Re: Brake Bleeding Nightmare |
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A bad MC out of the box isn't unheard of, specially if its one of the cheaper ones. Could also be an obstruction in the rear brake line somewhere.
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TDCTDI
Samba Advocatus Diaboli
Joined: August 31, 2013
Posts: 12858
Location: North Carolina
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| Posted: Fri Mar 16, 2018 12:41 pm Post subject: Re: Brake Bleeding Nightmare |
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| usmcbrowns wrote: |
Bench bled the MC twice. When we bleed the brakes, the rear pedal only goes 1/2 down when the bleeder is opened. It just stops and wont go any further than 1/2 way to the floor. When the front bleeders are open, pedal travels to the floor.
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when you open the rear circuit & the pedal only goes halfway, this means that the front circuit is working & is mostly if not completely bled.
When you open the front circuit & the pedal goes to the floor, this means that the rear circuit has air in it or there is a leak somewhere. If you aren't seeing fluid on the ground somewhere, pull up the carpet under the driver side seat & check for leaks in the line going from the master cylinder to the rear of the car.
How are you bleeding the system? If you are pumping the brakes manually, it's possible that the fluid/air is just flowing back as you're releasing the brake pedal, sometimes there isn't enough pedal travel to purge an air pocket in a high spot & it travels back to the high spot (like the line above the rear torsion housing.) when you release the pedal.
Put a hose over the bleeder valve, loop it up over the tire & then into a catch bottle, barely open the bleeder so there is some resistance for return flow (there are "self bleeder" valves available at some parts stores.) & just pump the pedal repeatedly until you can get half a pint or so out of it (have someone keep the reservoir topped off), close the valve & go to the other side & repeat.
You also need to make sure that the shoes are properly adjusted all the way around as this will add lots of frustration when the shoes have extra travel.
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4026
Location: WA
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| Posted: Fri Mar 16, 2018 2:51 pm Post subject: Re: Brake Bleeding Nightmare |
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| Did you just replace the MC or do a whole brake job? What was the reason you replaced the original MC? If MC only remove all the drums and look for a bad wheel cyl., wet shoes, or leaking joints (if you find a joint don't bogart it). Are you bleeding them correctly, Have assistant pump pedal and hold, crack bleeder a little until pedal quits dropping and close valve BEFORE pedal is lifted and pump up again, hold, bleed, close valve, again repeat until all the bubbles stop then go to the next wheel. |
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usmcbrowns
Samba Member
Joined: July 02, 2015
Posts: 60
Location: Sneads Ferry, NC
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| Posted: Fri Mar 16, 2018 2:55 pm Post subject: Re: Brake Bleeding Nightmare |
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The part that had me baffled was after hours of all this, thats when i noticed that if we bled the front circuit and had my son pump the brakes, i could see what looked like an air bubble or air pocket at the inlet. Where the blue hose attaches to the the MC. I can't figure out why there is/was an air pocket RIGHT THERE. Could the inlet be bad on the front circuit?? allowing air in?
Also... clearly there's air in there. I just can't figure out what else i need to do to get the air out of this blasted car.
This is my son's car. He's at work right now. I'll check the line running down the center of the car. I'll look for fluid.
Last thing... the Drivers Front Caliper... when i loosen the bleeder valve.. it feels LOOSE. Now i know that's because i loosened the bleeder valve.. but if i barely crack the bleeder, even with a hose on the end of the bleeder, brake fluid seems to be running out that hole and down the caliper.
Again, this thing has more air in it than a freshly opened soda can. It's driving me crazy.
Thanks guys.
Any other advice is welcome.
MB
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71 Super Beetle, 1641
2011 Ram 2500 Diesel
2013 GMC Acadia
2014 Stingray
2004 KLR 650 |
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Starbucket
Samba Member
Joined: April 30, 2007
Posts: 4026
Location: WA
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| Posted: Fri Mar 16, 2018 3:28 pm Post subject: Re: Brake Bleeding Nightmare |
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| I would look closely at the blue hose nipple for a crack and any leakage there. If you got the MC at the local auto parts store take it back and get another one as that one must have internal problems, if you don't find a leak. A bad wheel cyl. should have fluid leaking from bottom edge of drum or the pads/disc. Don't let the pedal going 1/2 way down bother you when bleeding, that's why you can still stop if a line or such fails, two wheels will still stop you (front or rear). |
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theKbStockpiler
Samba Member
Joined: July 07, 2012
Posts: 2316
Location: Rust Belt
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| Posted: Fri Mar 16, 2018 3:57 pm Post subject: Re: Brake Bleeding Nightmare |
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Make sure you have fluid comming out of all 4 bleeders.
Open one bleeder at a time only part way so the pedal goes down fairliy slowly (about 2 seconds). Don't concern yourself with having air go back in when releasing the pedal. With the bleeder still open this way, pump the pedal fast about 5 times about 3/4 of it's stroke , and then prop a piece of wood or something to keep it down all the way while you tighten the bleeder or just bleed this cylinder the normal way afterwards to make sure the air is out.
This method worked perfectly to get air out of a domestic master cylinder that I did not feel like trying to bleed at the master it's self.
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