brake problems
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5th Wheeling
Joined: May 2021
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brake problems
My name is Davis, and Im new to this website. I have a 1978 f250. I'm having brake issues with my front brakes. They are sticking every once in a while and I have to bleed pressure out of the lines at the master cylinder. Any suggestions as to where to start trouble shooting the problem?
Thanks
Thanks
Hotshot
Joined: Feb 2004
Posts: 10,726
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From: The Shenandoah Valley
I would check my temps with just the hand next time, if a brake hose is blocking return due to an imnternal fault on a line, a mile or so will heat that brake up hot enough you'll feel it just getting close to that brake, you will not want to touch it ... so don't. If you smell it and step on the brake as it's moving and the steering wheel is pulled left, it's the right front brake and vicey versa. If it seams to be all of them ... or just one end as you said, could be the brake proportioning block in the left frame rail under the M-C. If you do try to loosen a tube nut on the MC, the rear "larger" reservoir is front brakes.
1976-86 Ford F150 F250 F350 Truck Disc Drum Brake Line Proportioning Valve Combo | eBay
1976-86 Ford F150 F250 F350 Truck Disc Drum Brake Line Proportioning Valve Combo | eBay
FTE Legend
Joined: Nov 2015
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From: Angier, NC
At first I was going to say hose but he is undoing a line at the master so it's that whole system master to wheel.
If it was a bad hose then undoing a line at the master would not release the pressure.
Dave. ----
If it was a bad hose then undoing a line at the master would not release the pressure.
Dave. ----
Lead Driver
Joined: Nov 2006
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From: Pa.
The rubber brake hose that runs from the hard line to the caliper when old can become pliable and collapse from a vacuum created in the line. This condition has similar symptoms as mentioned by the OP. The solution is to replace both the rubber brake hoses.
FTE Legend
Joined: Nov 2015
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From: Angier, NC
If he undid the line at the master and it's under a vacuum it would let air into the system and no fluid would leak out.
If it had pressure when he opens the fitting at the master fluid would pass out.
Now don't get me wrong if the hoses are old yes just replace them but I would want to know what the cause is before throwing parts at it.
Rod adjustment at the master If to long will not let the pistons back all the way holding pressure on the system..
That is why I said to loosen the master to see what happens.
Dave. ----
Lead Driver
Joined: Nov 2006
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From: Pa.
So you are saying there is a vacuum between master and the 2 rubber lines and that is why they are holding pressure?
If he undid the line at the master and it's under a vacuum it would let air into the system and no fluid would leak out.
If it had pressure when he opens the fitting at the master fluid would pass out.
Now don't get me wrong if the hoses are old yes just replace them but I would want to know what the cause is before throwing parts at it.
Rod adjustment at the master If to long will not let the pistons back all the way holding pressure on the system..
That is why I said to loosen the master to see what happens.
Dave. ----
If he undid the line at the master and it's under a vacuum it would let air into the system and no fluid would leak out.
If it had pressure when he opens the fitting at the master fluid would pass out.
Now don't get me wrong if the hoses are old yes just replace them but I would want to know what the cause is before throwing parts at it.
Rod adjustment at the master If to long will not let the pistons back all the way holding pressure on the system..
That is why I said to loosen the master to see what happens.
Dave. ----
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Hotshot
Joined: Feb 2004
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From: The Shenandoah Valley
I just went through it last October on my '77, was a old hose on left front so I replaced both. Like in the picture, a piece of liner gets loose patly, you press on the pedal, fluid moves it and passes, then when you releas the braske, the now reversed fluid pushes that rubber piece into small undamage portion, and it's enough to hold the brake applied or not fully released. Cracking the bleeder will release it until the next time you use the brakes. My left front, my shop air could not blow through it in reverse direction. If cracking the bleeder doesn't release the brake, think caliper.
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FTE Legend
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From: Angier, NC
Dave ----
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Joined: Nov 2006
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From: Pa.
I know that is what happens but the OP said he undid a fitting at the master how would that remove pressure at the caliper if the line was plugged?
Dave ----
Dave ----
They are sticking every once in a while and I have to bleed pressure out of the lines at the master cylinder. Any suggestions as to where to start trouble shooting the problem?
Thread Starter
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5th Wheeling
Joined: May 2021
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Thanks for all the valuable input. It sounds like the problem has been narrowed down the to rubber brake lines. I ordered 2 new rubber brake lines. I will let you Guys know if that solves the problem. Thanks again for the help.
Lead Driver
Joined: Nov 2006
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From: Pa.
A few notes when you go to replace your rubber brake lines:
1) When separating the hard line from the rubber line use a line wrench to secure the hard line to insure no twisting of the hard line otherwise you might end up replacing it also.
2) The metal bracket that secures the union of the two lines is no longer being made so be extra careful with it.
3) Be sure the new brake hoses have new copper mounting washers included.
1) When separating the hard line from the rubber line use a line wrench to secure the hard line to insure no twisting of the hard line otherwise you might end up replacing it also.
2) The metal bracket that secures the union of the two lines is no longer being made so be extra careful with it.
3) Be sure the new brake hoses have new copper mounting washers included.
Trailering
Joined: Apr 2021
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WAS IT THE RUBBER BRAKE LINES?
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