Help with my brakes

"Funktheduck" (funktheduck) 01/28/2017 at 19:00 • Filed to: None

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So, as I have half assed updated about my truck in the past I’ve been working on the brakes the past few weekends. Now I’m a bit stuck just in front of the finish line and ask for your knowledge.

The truck: 1979 F150

The brakes: discs up front, drums in the back

What’s been done: new master cylinder and brake booster (bench bled), new flexible lines (2 up front, one in back), and one hard line (driver’s side)

The problem: nothing happening when bleeding on two wheels. I’m using a vacuum pump (Mityvac) to help with the process. 1st wheel done was the passenger side rear with no real issues. Drivers side rear next and nothing. The bleeder scores allows fluid/air to pass but once I screw it back into the wheel cylinder nothing happens. It just holds vacuum until I back the screw out to the point that air leaks in through the threads. Decide to leave it alone for the time being and check the other wheels. Drivers side front is no issue. Passenger side front has the same issue as the drivers side rear. Do I need a new wheel cylinder and caliper? Is it a problem in the lines? Any way to test? Anything else?

MM54 > Funktheduck 01/28/2017 at 19:39

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You’re sure the only thing coming out is air via the threads and not just the (relative) ton of air in the new lines? I’d be tempted to gravity bleed it overnight and see if maybe it’s just a lot of air, otherwise it sounds like there’s a blockage (pinched line, etc) somewhere.

For what it’s worth, I’ve not had much luck with vacuum bleeders, especially when there’s a lot of air in the system. Speed bleeders are pretty cool for single-person bleeding, but it’s hard to beat getting someone to help in terms of efficacy.

Funktheduck > MM54 01/28/2017 at 20:00

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Very sure about air through the threads. I’m leaning towards blockage as well. Called it a day when the sun was completely down and the temp started dropping quickly. Laying on cold concrete with the wind blowing isn’t fun. May try gravity bleeding.

The rear will be really easy to check for blockage and replace the hard line if needed. The front passenger line will be more difficult.

crowmolly > Funktheduck 01/28/2017 at 20:12

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The bleeder scores allows fluid/air to pass but once I screw it back into the wheel cylinder nothing happens. It just holds vacuum until I back the screw out to the point that air leaks in through the threads.

Sorry, not 100% following.

Are you saying when you crack the bleeder no fluid comes through the middle, it just holds vacuum- unless you crack the bleeder enough that fluid and air seep by the threads?

Junkrat aka Rick Sanchez: Fury Road Edition > Funktheduck 01/28/2017 at 20:27

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Clogged bleeders? No resistance in the pedal at all, even if you pump it up? If you can build up some pedal feel, I would borrow whoever you can to pump up the brakes and you go to the problem corner and open the bleeder. If they pedal goes to the floor, more than likely you don’t have a blockage. Then keep doing that until your brakes are bled. I’ve never had much luck with the vacuum pumps, but I do love my Motive bleeder.

Funktheduck > Junkrat aka Rick Sanchez: Fury Road Edition 01/28/2017 at 20:33

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Have pedal resistance. Leaning towards a clog somewhere after talking to a few people.

Funktheduck > crowmolly 01/28/2017 at 20:34

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No fluid. Just air. Supposed to be bleeder screws. Autocorrect

crowmolly > Funktheduck 01/28/2017 at 20:39

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Did you try to pump the brakes at all to push the fluid column?

DC3 LS, will be perpetually replacing cars until the end of time > Funktheduck 01/28/2017 at 20:49

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I would just get a new bleeder screw, they’re like $2.

Funktheduck > crowmolly 01/28/2017 at 21:43

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I did some pumping but held off on doing too much in case there was an issue

crowmolly > Funktheduck 01/28/2017 at 21:45

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OK, wasn’t sure. Sounds like there’s a blockage somewhere.

Funktheduck > crowmolly 01/28/2017 at 22:23

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Yeah. Between oppo and talking to others, everyone is leaning towards blockage.

merged-5876237249235911857-hrw8uc > Junkrat aka Rick Sanchez: Fury Road Edition 01/29/2017 at 00:23

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I’ll second the motive bleeder, works awesome. I’ve used the mityvac too in the past and had to add thread sealant to the bleeder screw threads to keep the air getting vacced out when the bleeder was cracked open. But now with the motive, it’s easy-peasey. You can set it up on the reservoir and just pull one wheel at a time and leave the pressure on and work your way around the car. So very nice. And no need for a second person or all that damn pumping and holding.